The FDA has approved cefiderocol (Fetroja – Shionogi), a new IV cephalosporin antibiotic, for treatment of complicated urinary tract infections (UTI) caused by susceptible gram-negative bacteria in adults who have limited or no alternative treatment options.

This issue includes reviews of drugs for glaucoma, age-related macular degeneration (AMD), bacterial conjunctivitis, and dry eye disease. Allergic conjunctivitis is reviewed in a separate issue.

Patients who receive pretravel advice can reduce their risk for many travel-related conditions. Vaccines recommended for travelers are reviewed in a separate issue.

View the Expanded Table: Antibiotics for Travelers' Diarrhea

The FDA has approved rifamycin (Aemcolo – Cosmo/ Aries), a minimally absorbed oral antibiotic, for treatment of adults with travelers' diarrhea (TD) caused by noninvasive strains of Escherichia coli. It is not recommended for treatment of diarrhea that is complicated by fever and/or bloody stools. Topical and injectable formulations of rifamycin have been used in Europe for other indications for many years.

The FDA has approved the new aminoglycoside antibiotic plazomicin (Zemdri – Achaogen) for IV treatment of adults with complicated urinary tract infections (cUTIs). Plazomicin is active against multi-drug- resistant Enterobacteriaceae, including strains resistant to other aminoglycosides.

The FDA has approved obiltoxaximab (Anthim – Elusys Therapeutics), a toxin-targeting monoclonal antibody, for treatment of inhalational anthrax in combination with antibacterial drugs and prophylaxis of inhalational anthrax when other therapies are unavailable or inappropriate. Raxibacumab, another monoclonal antibody, was approved earlier for the same indication. Like raxibacumab, obiltoxaximab is being manufactured only for the CDC national stockpile and is not available for commercial sale.

The FDA has approved a 6% otic suspension formulation of the fluoroquinolone antibiotic ciprofloxacin (Otiprio – Otonomy) for single-dose treatment of acute otitis externa (swimmer's ear) caused by Pseudomonas aeruginosa or Staphylococcus aureus in patients ≥6 months old. Otiprio was approved earlier for prophylaxis in children with bilateral otitis media with effusion who are undergoing tympanostomy tube placement.

View Table: Drugs for Ulcerative Colitis

View Table: Drugs for Crohn's Disease

The FDA has approved a fixed-dose combination of meropenem, a carbapenem antibiotic, and vaborbactam, a new beta-lactamase inhibitor (Vabomere – Melinta), for IV treatment of adults with complicated urinary tract infections (UTIs) that are proven or strongly suspected to be caused by Escherichia coli, Klebsiella pneumoniae, or Enterobacter cloacae spp. complex. Meropenem (Merrem, and generics) has been approved for years for treatment of complicated skin and skin structure infections, intra-abdominal infections, and bacterial meningitis. Resistance to meropenem and other carbapenems, mainly due to production of carbapenemases and other extended-spectrum beta-lactamases (ESBLs), has been increasing worldwide, particularly among Enterobacteriaceae. Vabomere is the first carbapenem/beta-lactamase inhibitor combination to be marketed in the US.

The FDA has approved delafloxacin (Baxdela – Melinta), an anionic fluoroquinolone antibiotic, for oral and parenteral treatment of adults with acute bacterial skin and skin structure infections (ABSSSIs), including those caused by methicillin-resistant Staphylococcus aureus (MRSA). It is the first fluoroquinolone to be approved for treatment of MRSA.

View the Comparison Table: Some Systemic Fluoroquinolones (online only)

Bacterial infections in adults are generally treated empirically, with the antibiotic covering most, but not all, of the potential causative pathogens. For some infections, culture and sensitivity testing can guide treatment, allowing for use of narrower-spectrum antibiotics. The recommended dosages and durations of antibiotic treatment for common respiratory, skin, and urinary tract infections are listed in Tables 1-3. Infectious disease experts now recommend shorter treatment durations for many infections to reduce the development of antimicrobial resistance and minimize adverse effects.

The FDA has approved Otovel (Arbor), a combination of the fluoroquinolone antibiotic ciprofloxacin 0.3% and the corticosteroid fluocinolone acetonide 0.025%, for otic treatment of acute otitis media with tympanostomy tubes (AOMT) in children ≥6 months old. It is the second fluoroquinolone/corticosteroid combination to be approved for this indication; ciprofloxacin 0.3%/dexamethasone 0.1% (Ciprodex) has been available for many years. In December 2015, a suspension of ciprofloxacin 6% (Otiprio) was approved for otic treatment of bilateral otitis media with effusion in children undergoing tympanostomy tube placement.

The FDA has announced that it is requiring changes in the labeling of systemic fluoroquinolones to warn that the risk of serious adverse effects, including tendinitis, peripheral neuropathy and CNS effects, generally outweighs their benefit for the treatment of acute sinusitis, acute exacerbations of chronic bronchitis, and uncomplicated urinary tract infections. For these infections, the new labels will recommend reserving fluoroquinolones for patients with no other treatment options.

Antimicrobial prophylaxis can decrease the incidence of postoperative surgical site infection after some procedures. Since the last Medical Letter article on this subject, consensus guidelines have been published. Recommendations for prophylaxis in specific surgical procedures are listed in Table 1.

The FDA has approved ciprofloxacin 6% otic suspension (Otiprio – Otonomy) for single-dose prophylaxis in children with bilateral otitis media with effusion who are undergoing tympanostomy tube placement. It is the first drug to be approved for this indication in the US. Otic formulations of the fluoroquinolone antibiotics ofloxacin (Floxin Otic, and generics) and ciprofloxacin (plus dexamethasone; Ciprodex) have been available for years for treatment of acute otitis media in children with tympanostomy tubes; an otic suspension containing ciprofloxacin and fluocinolone acetonide (Otovel) has recently been approved for the same indication and will be reviewed in a future issue.

Primary hypothyroidism is usually the result of Hashimoto's thyroiditis, thyroidectomy, or radioactive iodine therapy. Treatment of hypothyroidism with replacement doses of thyroid hormone is usually lifelong. Levothyroxine is the drug of choice.

The FDA has approved ceftazidime/avibactam (Avycaz – Actavis) for IV treatment of complicated urinary tract and intra-abdominal infections in adults who have limited or no other treatment options. Ceftolozane/tazobactam (Zerbaxa – Cubist), another cephalosporin/beta-lactamase inhibitor combination, was approved in 2014.

Patients planning to travel to other countries often ask for information about prevention of diarrhea, malaria, and other travel-related conditions. Vaccines recommended for travelers based on their destination, length of stay, and planned activities were reviewed in a previous issue.

The FDA has approved ceftolozane/tazobactam (Zerbaxa – Cubist), a combination of a new cephalosporin antibiotic and a beta-lactamase inhibitor, for intravenous treatment of complicated urinary tract and intra-abdominal infections in adults.

Aminosalicylates are effective for induction and maintenance of remission in mild to moderate ulcerative colitis. They are not recommended for treatment of Crohn's disease.

FORMULATIONS — Oral mesalamine is rapidly absorbed in the small intestine and most of the drug does not reach the colon. Pentasa releases mesalamine gradually throughout the gastrointestinal tract. Delzicol, Asacol HD, Lialda, and Apriso delay the release of the drug until it reaches the distal ileum and colon. Sulfasalazine (Azulfidine, and generics), balsalazide (Colazal, and others), and olsalazine (Dipentum) are prodrugs; mesalamine is azo-bonded to a second moiety and released in the colon following bacterial cleavage of the bond. Mesalamine is also available as an enema (Rowasa, and generics) and as a rectal suppository (Canasa).

An outbreak (8 cases to date) of meningococcal disease at Princeton University caused by Neisseria meningitidis serogroup B has led the FDA and CDC to permit importation and investigational use (at Princeton University only) of a meningococcus B vaccine (4CMenB; Bexsero – Novartis) that has not been approved in the US. Bexsero has been approved for use in the European Union and in Australia.

THE VACCINE — Until recently, no serogroup B vaccine was widely available because the polysaccharide capsule of the B serogroup, unlike those of the other main meningococcal serogroups (A, C, Y, and W-135), is only weakly immunogenic. The 4CMenB vaccine contains 3 protein antigens identified in the N. meningitidis serogroup B genome and membrane components from a New Zealand outbreak strain. The vaccine has been tested in more than 8000 adults and children, has proved to be immunogenic, and appears to be safe.1 Its efficacy has not been established clinically, but laboratory testing, according to the CDC, has found that the vaccine should be protective against the strain causing the Princeton University outbreak. Bactericidal antibody levels develop about 2 weeks after one dose of the vaccine; a second dose is needed 1-6 months after the first to maintain protection.

CHEMOPROPHYLAXIS — Close contacts of patients with invasive meningococcal disease (e.g., same household, roommates, boyfriend or girlfriend) should receive antimicrobial chemoprophylaxis. Antimicrobial drugs can prevent secondary cases and eradicate the organism from the nasopharynx of healthy carriers. The susceptibility of serogroup B meningococci to antimicrobial agents is the same as that of other meningococcal serogroups. Regimens recommended by the CDC’s Advisory Committee on Immunization Practices are: oral rifampin 600 mg (10 mg/kg for children) q12h for 2 days; oral ciprofloxacin 500 mg once (not recommended for children); or a single IM injection of ceftriaxone 250 mg (125 mg for children).2

CONCLUSION — The new vaccine against serogroup B meningococcal disease, which is investigational in the US, appears to be immunogenic and safe. For immediate protection after close contact with an infected patient, antimicrobial prophylaxis is recommended.

1. NJ Carter. Multicomponent meningococcal serogroup B vaccine (4CMenB; Bexsero®): a review of its use in primary and booster vaccination. BioDrugs 2013; 27:263.

2. AC Cohn et al. Prevention and control of meningococcal disease: recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR Recomm Rep 2013; 62(RR-2):1.

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The FDA is requiring new warnings about peripheral neuropathy in the labeling of all oral and injectable fluoroquinolones. The potential for this class of antibiotics to cause peripheral neuropathy was first identified more than 10 years ago and a warning was added to their labels in 2004. The new warnings are based on a recent review of the FDA’s Adverse Event Reporting System (AERS) database.1

The onset of peripheral neuropathy can occur rapidly, often within a few days of starting a fluoroquinolone, and in some patients the disorder may be permanent. Symptoms include pain, tingling, burning, numbness, weakness, and change in sensation to touch, pain, and temperature in the arms and/or legs. If peripheral neuropathy develops in a patient taking a fluoroquinolone, the drug should be stopped and an antibacterial from a different class should be used instead.2

1. FDA Drug Safety Communication: FDA requires label changes to warn of risk for possibly permanent nerve damage from antibacterial fluoroquinolone drugs taken by mouth or by injection. Available at http://www.fda.gov. Accessed November 1, 2013.

2. Drugs for bacterial infections. Treat Guidel Med Lett 2013; 11:65.

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The text that follows reviews some common bacterial infections and their empiric treatment pending the results of culture and susceptibility testing. The recommendations made here are based on the results of susceptibility studies, clinical trials, and the opinions of Medical Letter reviewers. Tables 1 and 2 list the usual dosages of antibacterial drugs.

The FDA has approved raxibacumab (rax” ee bak’ ue mab; GSK), a fully human monoclonal antibody given by intravenous infusion, for treatment of inhalational anthrax in combination with appropriate antibacterial drugs, and for prophylaxis of inhalational anthrax when alternative therapies are not available or are not appropriate. It was approved under the Animal Efficacy Rule, which allows the FDA to approve drugs that demonstrate efficacy in animals, providing that they would have a reasonable human health benefit and are safe for human use. Raxibacumab is only available from the CDC.

Drugs for glaucoma, age-related macular degeneration, bacterial conjunctivitis, and dry eyes are reviewed here. Drugs for the treatment of allergic conjunctivitis will be reviewed in a future issue of Treatment Guidelines on Drugs for Allergic Disorders.

Antimicrobial prophylaxis can decrease the incidence of postoperative infection, particularly surgical site infection, after some procedures. Recommendations for such prophylaxis are listed in the table that begins on page 74. Antimicrobial prophylaxis for dental procedures to prevent endocarditis was recently discussed in The Medical Letter.

A reader suggested that our July 23 article on Drugs for Urinary Tract Infection (Med Lett Drugs Ther 2012; 54:57)¹ should have included information on the cost of the drugs we recommended for treatment of acute uncomplicated cystitis.

Trimethoprim/sulfamethoxazole DS — Generic formulations are available at large discount pharmacies for $4 for 20 tablets. Trimethoprim/sulfamethoxazole DS is generally found on tier 1 (lowest co-pay) of insurance company formularies.

Nitrofurantoin monohydrate/macrocrystals — The wholesale acquisition cost of the generic formulation is about $2.50 per tablet (PricePointRx™).² The drug is on tier 1 of some insurance company formularies, but on tier 2 or 3 of others.

Fosfomycin — Available only as Monurol, a single dose of fosfomycin is effective in most cases of acute uncomplicated cystitis, but the manufacturer charges a wholesale acquisition cost of more than $40 for that dose (PricePointRx™).² Most insurance companies place Monurol on tier 3 of their formularies, or do not include it on their formularies at all.

Not recommended: Ciprofloxacin – Fluoroquinolones should not be used empirically to treat acute uncomplicated cystitis. The fact that ciprofloxacin is available at large discount pharmacies for $4 for 20 500-mg tablets and is on tier 1 on most insurance company formularies may be part of the reason for its continued overuse.

1. Drugs for urinary tract infection. Med Lett Drugs Ther 2012; 54:57.

2. PricePointRx™. Reprinted with permission by FDB. All rights reserved. ©2012. http://www.firstdatabank.com/support/drug-pricing-policy.aspx. Accessed July 31, 2012. Actual retail prices may be higher.

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The most recent guidelines from the Infectious Diseases Society of America (IDSA) and its European counterpart on the choice of antimicrobials for treatment of uncomplicated urinary tract infections (UTIs) in non-pregnant women focus on the unnecessary use of fluoroquinolones to treat uropathogens that are increasingly becoming resistant to them. Resistance of Escherichia coli to ciprofloxacin in the US has increased from 3% in 2000 to 17.1% in 2010.

Patients planning to travel to other countries often ask for information about appropriate vaccines and prevention of diarrhea and malaria. More detailed advice for travelers is available from the Centers for Disease Control and Prevention (CDC) at www.cdc.gov/travel. Guidelines are also available from the Infectious Diseases Society of America (IDSA).

Inflammatory bowel disease (IBD) is generally classified as either Crohn’s disease (CD) or ulcerative colitis (UC). More detailed guidelines on their treatment are available from the American College of Gastroenterology.

Many infections can be transmitted during sexual contact. The text and tables that follow are limited to management of sexually transmitted infections (STIs) other than HIV, viral hepatitis and enteric infections. The drugs of choice, their dosages and alternatives are listed in a table that begins on page 54. A table listing the adverse effects of some of these antimicrobials begins on page 58.

The text below reviews some common bacterial infections and their treatment. The recommendations made here are based on the results of susceptibility studies, clinical trials and the opinions of Medical Letter consultants.

Drugs for glaucoma, age-related macular degeneration, bacterial conjunctivitis, and dry eyes are reviewed here. Ophthalmic drugs can have local and systemic adverse effects. In addition, for some elderly patients, the complexity of self-administering numerous ophthalmic drugs may be the limiting factor in their ability to care for themselves. Drugs for the treatment of allergic conjunctivitis will be reviewed in a future issue of Treatment Guidelines on Drugs for Allergic Disorders.

The FDA has approved the fluoroquinolone besifloxacin 0.6% ophthalmic suspension (Besivance - Bausch & Lomb) for treatment of bacterial conjunctivitis caused by susceptible bacteria. According to the manufacturer, this product was developed specifically for ophthalmic use in a specialized vehicle designed to prolong contact time on the ocular surface. Besifloxacin is not available for systemic use.

Patients planning to travel to other countries often ask physicians for information about appropriate vaccines and prevention of diarrhea and malaria. Guidelines are also available from the Infectious Diseases Society of America (IDSA).

Inflammatory bowel disease (IBD) is either Crohn's disease or ulcerative colitis. Drug selection is guided by disease type (Crohn's versus ulcerative colitis), severity and location and whether the goal is induction or maintenance of remission. Table 1 on page 66 lists the drugs used to treat IBD with their formulations and cost. Table 2 on page 68 lists the drugs of choice and their doses for different indications. Table 3 on page 71 lists the drugs' adverse effects and recommendations for monitoring. More detailed guidelines are available from the American College of Gastroenterology.

Primary hypothyroidism is usually the result of Hashimoto's thyroiditis, thyroidectomy for hyperthyroidism, goiter or cancer, or radioactive iodine therapy for hyperthyroidism.

Antimicrobial prophylaxis can decrease the incidence of infection, particularly surgical site infection, after certain procedures. Recommendations for prevention of surgical site infection are listed in the table that begins on page 48. Antimicrobial prophylaxis for dental procedures to prevent endocarditis is discussed in The Medical Letter 2007; 49:99.

The majority of patients with insomnia do not have a predisposing psychiatric disease. Rather, untreated insomnia may be a risk factor for development of psychiatric problems such as depression or anxiety.

The FDA has added a boxed warning to fluoroquinolone package inserts about tendon injuries that may occur as a result of their use. Tendinitis or tendon rupture may occur rarely with systemic use of any fluoroquinolone, either while the drug is being taken or for up to several months afterwards.

Fluoroquinolone-related tendon injury is rare; estimates for its incidence in the general population range from 0.14% to 0.4%. The risk is higher for patients >60 years old and for those taking corticosteroids. For patients with organ transplants, the incidence may be as high as 15%.1 A case-control study in Italy involving 22,194 cases of non-traumatic tendinitis and 104,906 controls found that fluoroquinolone use was significantly associated with tendon disorders in general (OR 1.7; 95% CI 1.4-2.0), tendon rupture (OR 1.3; 95% CI 1.0-1.8), and Achilles tendon rupture (OR 4.1; 95% CI 1.8-9.6). Achilles tendon rupture occurred with fluoroquinolone treatment in one of every 5989 patients in general and in one of every 1638 patients >60 years old.2

Widespread use of fluoroquinolones, particularly for treatment of respiratory infections, has produced substantial bacterial resistance to this class of drugs and has been associated with an increase in the incidence and severity of Clostridium difficile disease.3 Even when bacterial pneumonia is considered a likely possibility, other drugs are generally preferred, at least in non-elderly, otherwise healthy patients.4

1. F Muzi et al. Fluoroquinolones-induced tendinitis and tendon rupture in kidney transplant recipients: 2 cases and a review of the literature.Transplant Proc 2007; 39:1673.
2. G Corrao et al. Evidence of tendinitis provoked by fluoroquinolone treatment: a case-control study. Drug Saf 2006; 29:889.
3. Treatment of Clostridium difficile-associated disease (CDAD). Med Lett Drugs Ther 2006; 48:89.
4. Drugs for community-acquired bacterial pneumonia. Med Lett Drugs Ther 2007; 49:62.

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(Med Lett Drugs Ther 2008; 50:91) In the Clinical Studies section, the complete response rate with chlorambucil for CLL was 2% (not 24%).

Bendamustine HCl (Treanda - Cephalon), an unusual DNA-alkylating agent that has been used in Europe for many years to treat lymphoma, has now been approved by the FDA for treatment of chronic lymphocytic leukemia (CLL) and non-Hodgkin's lymphoma (NHL).

Duloxetine (Cymbalta - Lilly) is the second drug to be approved by the FDA for treatment of fibromyalgia. Pregabalin (Lyrica), which is also approved for treatment of neuropathic pain and epilepsy, was the first. Duloxetine is a selective serotonin and norepinephrine reuptake inhibitor (SNRI) that is already marketed for treatment of depression and diabetic neuropathy.

The most common cause of travelers' diarrhea, usually a self-limited illness without fever lasting several days, is infection with noninvasive enterotoxigenic (ETEC) or enteroaggregative (EAEC) strains of Escherichia coli. Campylobacter, Shigella, Salmonella, Aeromonas, viruses and parasites are less common.

The May 5, 2008 article (Med Lett Drugs Ther 2008; 50:34) on the approval of natalizumab (Tysabri) for treatment of Crohn's disease in the "Adverse Effects" section on page 35 included the statement: "post-marketing hepatotoxicity, sometimes fatal or requiring liver transplantation, has occurred." Actually, no fatal hepatotoxicity or liver transplantation has been reported to date. The FDA warning about post-marketing hepatotoxicity with Tysabri that was the basis for our statement said: "The combination of transaminase elevations and elevated bilirubin without evidence of obstruction is recognized as an important predictor of severe liver injury that may lead to [emphasis added] death or the need for a liver transplant in some patients." Also, in the last sentence of the Conclusion, we should have said: "Because of the risk of serious hepatic toxicity and the rare but even more serious risk of developing progressive multifocal leukoencephalopathy, it should be used only in patients who have not responded to other drugs, including a TNF inhibitor." The italicized words should be substituted for "it is FDA-approved for use."

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Natalizumab (Tysabri - Elan and Biogen) is a monoclonal antibody approved for induction and maintenance treatment of moderate to severe Crohn's disease (CD) refractory to conventional therapies and inhibitors of tumor necrosis factor (TNF). Initially approved in 2004 for the treatment of multiple sclerosis (MS), natalizumab was temporarily withdrawn from the market after 3 patients developed progressive multifocal leukoencephalopathy (PML). It is now available for treatment of both MS and CD through a restricted distribution program.

The CDC recently reported that fluoroquinoloneresistant strains of Neisseria meningitidis have been detected for the first time in the US in an area around the border of North Dakota and Minnesota (CDC. MMWR, Feb 22, 2008). These isolates were all serogroup B, for which meningococcal vaccines (Med Lett Drugs Ther 2005; 47:29) do not offer protection. Since many laboratories do not test N. meningitidis for antimicrobial susceptibility, it is possible that such resistance is more widespread.

A single oral dose of ciprofloxacin (Cipro, and others) 500 mg has been used for prophylaxis after close contact with infected patients. Oral rifampin (Rifadin, and others) 600 mg (10 mg/kg for children) q12h for 2 days, a single IM injection of ceftriaxone (Rocephin, and others) 250 mg (125 mg for children), or a single oral dose of azithromycin (Zithromax, and others) 500 mg (10 mg/kg for children) are reasonable alternatives.

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Doripenem (Doribax - Ortho-McNeil Janssen), an intravenous (IV) carbapenem antibiotic with a spectrum of activity similar to that of imipenem and meropenem, has been approved by the FDA for treatment of complicated intra-abdominal and urinary tract infections. Use of doripenem for treatment of nosocomial pneumonia, including ventilator-associated pneumonia, is still under FDA review.

Many infections can be transmitted during sexual contact. The text and tables that follow are limited to management of sexually transmitted infections (STIs) other than HIV, viral hepatitis and enteric infections. Guidelines are available from the US Centers for Disease Control and Prevention (CDC) with detailed recommendations for treatment of these diseases.

Information about empirical treatment of bacterial infections, emerging trends in antimicrobial resistance, new drugs and new data about older drugs continue to become available. Usual pathogens and empiric treatment for some common types of infections are summarized in the text and a table listing the drugs of choice and alternatives for each pathogen begins on page 40. The recommendations made here are based on the results of susceptibility studies, clinical trials and the opinions of Medical Letter consultants.

Antimicrobial prophylaxis can decrease the incidence of infection, particularly surgical site infection, after certain procedures. Recommendations for prevention of surgical site infection are listed in this article.

Ramelteon (Rozerem - Takeda), a melatonin receptor agonist, has been approved by the FDA for treatment of insomnia characterized by difficulty falling asleep. Unlike all other prescription hypnotics, which are classified as schedule IV drugs, ramelteon is not a controlled substance.

Duloxetine hydrochloride (Cymbalta - Lilly), a selective serotonin and norepinephrine reuptake inhibitor (SNRI) available for treatment of depression, has also been approved by the FDA for treatment of neuropathic pain associated with diabetic peripheral neuropathy (DPN). Duloxetine is one of two drugs approved specifically for management of neuropathic pain due to diabetes; the other, pregabalin (Lyrica - Pfizer), will be marketed soon and will be reviewed in the next issue of The Medical Letter.

The FDA has reported that 5106 elderly patients with dementia treated with atypical (second generation) antipsychotics in 17 randomized controlled trials had a higher mortality rate (4.5% vs. 2.6%) than those receiving placebo. Most of the deaths were due to cardiovascular and infectious causes (such as pneumonia). The drugs used in the trials were aripiprazole (Abilify), olanzapine (Zyprexa), quetiapine (Seroquel), and risperidone (Risperdal). As the increase in mortality was considered a class effect, the FDA advisory also included ziprasidone (Geodon), clozapine (Clozaril) and the olanzapine/fluoxetine combination (Symbyax). The manufacturers of all of these drugs will be required to add a "black box" warning to their labeling.

Serious adverse interactions between drugs continue to be reported. Many of these are due to inhibition or induction of cytochrome P450 (CYP) enzymes, particularly CYP3A4. CYP3A is thought to be involved in the metabolism of more than 50 percent of currently prescribed drugs.2 CYP3A4, which is more abundantly expressed than CYP3A5, accounts for most CYP3A activity in vivo.

Tuberculosis (TB) is still a problem in the United States, even though the incidence continues to decline in most of the country (MMWR Morbid Mortal Wkly Rep 2004; 53:209). Treatment of TB can be divided into treatment of latent infection diagnosed by a positive PPD and treatment of active clinical TB. Guidelines with detailed management recommendations are available from the US Centers for Disease Control and Prevention (CDC) (MMWR Morbid Mortal Wkly Rep 2003; 52RR-11:1).

Many infections can be transmitted during sexual contact. The text and tables that follow are limited to management of sexually transmitted infections (STIs) other than HIV, viral hepatitis and enteric infections. Guidelines are available from the US Centers for Disease Control and Prevention (CDC) with detailed recommendations for treatment of these diseases (MMWR Recomm Rep 2002; 51, RR-6:1). New guidelines are expected soon.

Gemifloxacin (Factive - Oscient), a new oral fluoroquinolone antibiotic, has been approved by the FDA for 5 days' treatment of acute bacterial exacerbations of chronic bronchitis (ABECB) and 7 days' treatment of mild to moderate community-acquired pneumonia (CAP) in adults. For the next 6-8 months it will only be available, presumably for commercial reasons, in states east of the Rocky Mountains.

Rifaximin (Xifaxan - Salix), a non-absorbed oral antibiotic derived from rifampin (Rifadin, and others), has been approved by the FDA for treatment of travelers' diarrhea caused by noninvasive strains of Escherichia coli in patients 12 years of age or older. It has been available in Europe since 1987.

Patients planning to travel to other countries often ask physicians for advice about immunizations and prevention of diarrhea and malaria. More detailed advice for travelers is available from the Centers for Disease Control (CDC) at 877-FYI-TRIP (877-394-8747) or www.cdc.gov/travel. Recommendations for the treatment of parasitic diseases are available in the public reading room of The Medical Letter's web site.

Antimicrobial prophylaxis can decrease the incidence of infection, particularly surgical site infection, after certain operations, but this benefit must be weighed against the risks of toxic and allergic reactions, emergence of resistant bacteria, adverse drug interactions, superinfection and cost. Medical Letter consultants generally recommend antimicrobial prophylaxis only for procedures with high infection rates, those involving implantation of prosthetic material, and those in which the consequences of infection are likely to be especially serious.

Two new fluoroquinolone solutions, moxifloxacin 0.5% (Vigamox - Alcon) and gatifloxacin 0.3% (Zymar - Allergan) are now available in the US for ophthalmic use in treatment of bacterial conjunctivitis.

New drugs for bacterial infections and new information about older drugs continue to become available. Empirical treatment of some common bacterial infections is discussed in this article. A table listing the drugs of choice and alternatives for each pathogen begins on page 18. These recommendations are based on results of susceptibility studies, clinical trials and the opinions of Medical Letter consultants. Local resistance patterns should be taken into account. Trade names are listed on page 24.

Management of intermittent claudication, the most common symptom of peripheral arterial disease (PAD), involves both risk factor modification and symptomatic treatment (WR Hiatt, N Engl J Med 2001; 344:1608; RM Schainfeld, J Am Board Fam Pract 2001; 14:443).

New drug approvals as well as continuing concerns about drug toxicity and the development of resistance have prompted new antiretroviral treatment guidelines (Panel on Clinical Practices for Treatment of HIV Infection, November 10, 2003, www.aidsinfo.nih.gov).

The choice of drugs for treatment of pneumonia depends on the most likely pathogens causing the infection and local antimicrobial resistance patterns. Factors such as severity of illness, presence of co-morbid conditions and whether the infection is community or hospital-acquired also need to be considered.

The July 2003 edition of the Canadian Adverse Reaction Newsletter, published by Health Canada (the Canadian FDA), reported that the Health Canada database had received more spontaneous reports of hypoglycemia (19) and hyperglycemia (7) with gatifloxacin (Tequin) than with other quinolone antibiotics.

Changes caused by one drug in the absorption, distribution, metabolism or excretion of another may lead to a pharmacokinetic adverse drug interaction (DN Juurlink et al, JAMA 2003; 289:1652). Additive drug interactions, such as vasodilation caused by both sildenafil (Viagra) and nitrates, can also have adverse effects.

Patients planning to travel to other countries often ask physicians for advice about immunizations and prevention of diarrhea and malaria. More detailed advice for travelers is available from the CDC at 877-FYI-TRIP (877-394-8747) or www.cdc.gov/travel.

Superseded by Handbook of Antimicrobial Therapy
The Medical Letter article on Drugs and Vaccines against Biological Weapons, published in the previous issue (October 15, 2001, page 87), included a brief discussion of post-exposure prophylaxis of inhalation anthrax. Recent events call for more detail.

Concerns have arisen anew about possible use of biological weapons. The pathogens considered most likely to be used for this purpose are discussed in this article. A good source for additional information is www.usamriid.army.mil/education/bluebook.html.

Many infections can be transmitted during sexual contact. The text and tables [in this article] are limited to treatment of non-HIV infections associated primarily with sexual transmission.

Patients planning to travel to other countries often ask pysicians for advice about immunizations and prevention of diarrhea and malaria. Legal requirements for entry and epidemiological conditions in different countries vary from time to time, often unpredictably, but some reasonable recommendations can be made.

Now that US Secretary of Defense has decided to vaccinate more than 2 million memebers of the US armed forces against anthrax, US physicians may be asked to answer some questions about the vaccine and the disease.

Trovafloxacin (Trovan - Pfizer) and its prodrug alatrofoxacin (Trovan IV) are new fluroroquinolones marketed for an unusually wide variety of infections, including oral and intravenous treatment of nosocomial and community-acquired pneumonia, acute ecerbations of chronic bronchitis, acute sinusitis, complicate intra-abdominal and pelvic infections, diabetic foot infection, uncomplicated urinary tract infection, prostatitis, cervicitis and uncomplicated gonorrhea.

Grepafloxacin (Raxar - Glaxo Wellcome), a once-daily oral fluoroquinolone, is now being marketed for treatment of community-acquired pneumonia, acute bacterial exacerbations of chronic bronchitis, uncomplicated gonorrhea, and nongonococcal urethritis and cervicitis.

Pramipexole (Mirapex - Pharmacia & Upjohn) and ropinirole (Requip - SmithKline Beecham), two new dopamine agonists, have been approved by the US Food and Drug Administration (FDA) for treatment of both early (without levodopa) and advanced (with levodopa) Parkinson's disease. Bromocriptine (Parlodel) and pergolide (Permax) are older dopamine agonists marketed in the USA for adjunctive use with levodopa.

Fosfomycin, a broad-spectrum antibiotic used parenterally in Europe for many years, has been approved by the US Food and Drug Administration (FDA) as fosfomycin tromethamine (Monurol - Forest) for single-dose oral treatment of uncomplicated urinary tract infections in women.

Sparfloxacin (Zagam - Rh ne-Poulenc Rorer) and levofloxacin (Levaquin - Ortho-McNeil) are the newest fluoroquinolone antimicrobials to be approved by the US Food and Drug Administration. Sparfloxacin in a once-daily oral preparation is being marketed for treatment of community-acquired pneumonia and acute bacterial exacerbations of chronic bronchitis. Levofloxacin, which is the active stereoisomer of ofloxacin (Floxin), is available for either oral or parenteral use; it is approved for oncedaily treatment of community-acquired pneumonia, acute exacerbations of chronic bronchitis, sinusitis, skin and skin structure infections and complicated urinary tract infections.

Olanzapine (Zyprexa - Lilly), a thienobenzodiazepine that structurally resembles and binds to many of the same receptors as clozapine (Clozaril), is now available in the USA for treatment of schizophrenia and other psychotic disorders.

Patients planning to travel to other countries often ask physicians for advice about immunizations and prevention of diarrhea and malaria. More detailed advice for travelers is available from the CDC at 877-FYI-TRIP (877-394-8747) or www.cdc.gov/travel.

Results of recently completed clinical trials have led to some changes in recommendation for treatment of human immunodeficiency virus (HIV) and other infections associated with AIDS.

Tuberculosis (TB) continues to be a major problem in the United States, particularly in areas where drug resistance is common (Morbid Mortal Weekly Rep, 44:387, May 26, 1995). Since poor compliance is the most important cause of treatment failure and is associated with emergence of drug resistence, some experts now recommend that all patients take drugs for TB under direct observation (SE Weis et al, N Engl J Med, 330:1179, 1994; R Bayer and D Wilkinson, Lancet, 345:1545, June 17, 1995).

The rising incidence of tuberculosis (TB) has been accompanied by a dramatic increase in drug resistance in some areas of the USA (TR Frieden et al, N Engl J Med, 328:521, 1993). Since poor compliance is the most important cause of treatment failure and associated with emergence of drug resistance, some experts now recommend that patients with TB take their drugs under direct obeservation (MD Iseman et al, N Engl J Med, 329:576, 1993).

Results of recently completed clinical trials have led to some changes in recommendations for treatment of human immunodeficiency virus (HIV) and other infections associted with AIDS.

Cefpodoxime proxetil (Vantin - Upjohn), a new third-generation oral cephalosporin, has been approved for marketing by the US Food and Drug Administration. It is available for twice-daily treatment of pharyngitis, upper and lower respiratory infections, otitis media, urinary tract infections, skin and soft tissue infections, and for single-dose treatment of uncomplicated gonorrhea in men or women and anorectal gonorrhea in women.

Enoxacin (en ox' a sin; Penetrex - Rh ne-Poulenc Rorer), a fluoroquinolone antimicrobial for oral use, has now been marketed in the USA for treatment of urinary tract infections and uncomplicated urethral or cervical gonorrhea.

Temafloxacin (Omniflox - Abbott) and lomefloxacin (Maxaquin - Searle) are the latest fluoroquinolone antimicrobial agents to be approved by the US Food and Drug Administration (FDA) for oral treatment of various infections. Previously marketed include norfloxacin (Noroxin - Medical Letter, 29:25, 1987), ciprofloxacin (Cipro - Medical Letter, 30:11, 1988), and ofloxacin (Floxin - Medical Letter, 33:71, 1991). Norfloxacin is marketed only for treatment of urinary tract infections, and lomefloxacin only for treatment of urinary tract infections and bronchitis known to be caused by Haemophilus influenzae or Moraxella catarrhalis. Ciprofloxacin and ofloxacin are also available in parenteral formulations.

Patients planning to travel to other countries often ask physicians for advice about immunizations and prevention of diarrhea and malaria. Legal requirements for entry and epidemiological conditions in different countries vary from time to time, often unpredictably, but some reasonable recommendations can be made. More detailed information is available in Health Information for International Travel, published annually by the Centers for Disease Control (CDC), which can be obtained from the Superintendent of Documents, US Government Printing Office, Washington, DC 20402. Up-to-date automated information is available by telephone from the CDC (404-332-4559).

After many years of decline in the USA, the incidence of tuberculosis (TB) has recently increased, partly because the disease occurs more frequently in patients with human immunodeficiency virus (HIV) infection and in the homeless (PF Barnes et al, N Engl J Med, 324:1644, 1991; Morbid Mortal Weekly Rep, 40:869, Dec 20, 1991).

Terfenadine (Seldane - Marion Merrell Dow) and astemizole (Hismanal - Janssen) are nonsedating antihistamines widely used to treat symptoms of allergic rhinitis (Medical Letter, 27:65, 1985; 31:43, 1989). Both are available without a prescription in Canada, and the US Food and Drug Administration is apparently considering terfenadine for over-the-counter availability in the USA.

Drugs that accelerate healing and prevent relapse or reurrence of peptic ulcers act either by decreasing gastric acidity or by enhancing mucosal defense mechanisms. Risk factors that may cause breakdown of mucosal defenses include the use of aspirinor other nonsteroidal anti-inflammatory drugs (NSAIDs) and the presence of Helicobacter pylori bacterial in the gastric antrum (AH Soll, Engl J Med, 322:909, 1990; WL Peterson, N Engl J Med, 324:1043, 1991).

Two new topical corticosteroids - fluticasone (Cutivate - Glaxo), a mediumpotency product, and halobetasol propionate (Ultravate - Westwood-Squibb), a superhigh- potency drug- were recently approved for marketing by the US Food and Drug Administration.

A growing number of clinical trials now permits some consensus on the treatment of human immunodeficiency virus (HIV) and other infections associated with acquired immune deficiency syndrome (AIDS) in adults.

Ciprofloxacin, previously available orally (Cipro - Medical Letter, 30:11, 1988) and for ophthalmic use (Ciloxan - Medical Letter, 33:52, May 31, 1991), is now the first fluoroquinolone antibiotic to become available in the USA in an intravenous (IV) formulation. Cipro I.V. (Miles) is being promoted as an alternative to third-generation cephalosporins, aminoglycosides, and other drugs used for treatment of serious infections.

Ofloxacin (Floxin - McNeil, Ortho), a new fluoroquinolone antibacterial agent, was recently marketed in the USA for oral treatment of various infections caused by susceptible microorganisms. Ofloxacin is the third fluoroquinolone to become available in this country. Norfloxacin (Noroxin - Medical Letter, 29:25, 1987) is marketed only for treatment of urinary tract infections. Ciprofloxacin (Cipro - Medical Letter, 30:11, 1988), like ofloxacin, is approved for use in a variety of infections.

An ophthalmic formulation of ciprofloxacin hydrochloride (Ciloxan - Alcon), a fluoroquinolone antibiotic, was recently marketed in the USA for treatment of bacterial keratitis and conjunctivitis. Ciprofloxacin has been used orally (Cipro) to treat a variety of serious infections (Medical Letter, 30:11, 1988) and recently was approved for intravenous administration.

With the deployment of hundreds of thousands of troops in Saudi Arabia, health problems endemic to the Arabian Peninsula may be coming to the attention of physicians in the USA and other areas.

Since the last Medical Letter review of cephalosporin antibiotics (volume 25, page 57, 1983), many new cephalosporins have become available in the USA.

Cefixime (Suprax - Lederle), an oral cephalosporin antibiotic, was recently approved for marketing by the US Food and Drug Administration. Claimed to be the first oral third-generation cephalosporin, the new drug is offered for once-a-day treatment of otitis media, pharyngitis, bronchitis and urinary tract infections.

A penicillin is the drug of choice for treatment of many infections, but allergic reactions to these drugs occur frequently and, rarely, can be fatal. From 5% to 20% of patients have a history of a rash or some other reaction while taking a penicillin, but maculopapular rashes with ampicillin or amoxicillin, especially in children with infectious mononucleosis, are probably not allergic.

Cefuroxime axetil (Ceftin - Glaxo), an oral form of the second-generation parenteral cephalosporin cefuroxime (Zinacef), was recently marketed in the USA. Previously available oral cephalosporins are the first-generation drugs cephalexin (Keflex; and others), cephradine (Anspor; and others) and cefadroxil (Duricef; and others), and the second-generation cefaclor (Ceclor); second-generation cephalosporins have more activity against gram-negative bacteria.

Ciprofloxacin hydrochloride (Cipro - Miles), a synthetic antibacterial agent, was recently marketed in the USA for oral treatment of a wide variety of infections. Ciprofloxacin is the second fluoroquinolone to become available in this country; norfloxacin (Noroxin - Medical Letter, 29:25, 1987) is marketed only for treatment of urinary tract infections. Fluoroquinolones are more potent and have a much broader spectrum of activity than older quinolones such as nalidixic acid (NegGram).