Treatment of epilepsy should begin with a single antiepileptic drug (AED), increasing its dosage gradually until seizures are controlled or adverse effects become intolerable. If seizures persist, specialists generally recommend trying at least one and sometimes a second alternative drug as monotherapy before considering use of two drugs concurrently. When used for the appropriate seizure type, AEDs are roughly equivalent in efficacy. Drug choice is usually based on factors such as ease of use, adverse effects, drug interactions, presence of comorbidities, and cost.

The treatment of atrial fibrillation includes anticoagulation, rate control, and rhythm control. New US guidelines for the management of atrial fibrillation have recently been published.

The FDA has approved ivacaftor (eye va kaf’ tor; Kalydeco – Vertex) for oral treatment of cystic fibrosis (CF) in patients ≥6 years old with the G551D mutation, which is found in about 5% of patients with CF. It is the first drug approved in the US that treats the cause of the disease.

Tuberculosis (TB) is still a common cause of death worldwide, and the prevalence of drug-resistant TB poses challenges to its treatment and control. Guidelines with detailed management recommendations are available from the American Thoracic Society, Centers for Disease Control and Prevention (CDC) and Infectious Diseases Society of America (IDSA).

The FDA has approved the marketing of tolvaptan (Samsca - Otsuka), an oral vasopressin receptor antagonist, for treatment of hypervolemic or euvolemic hyponatremia due to congestive heart failure (CHF), cirrhosis or the syndrome of inappropriate antidiuretic hormone secretion (SIADH). A similar drug, conivaptan (Vaprisol) is already available for intravenous (IV) treatment of euvolemic hyponatremia in hospitalized patients. Tolvaptan was approved by the FDA for both inpatient and outpatient use, but it should be started in a hospital.

Even though the incidence continues to decline in the United States, tuberculosis (TB) is still a common cause of death worldwide, and the prevalence of drug-resistant TB poses severe challenges to its treatment and control. Guidelines with detailed management recommendations are available from the Centers for Disease Control and Prevention (CDC), American Thoracic Society and Infectious Diseases Society of America (IDSA).

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.

A recent letter to the editor of the Annals of Internal Medicine documented a single case of myopathy apparently due to an interaction between simvastatin (Zocor, and others) and green tea. Since it became available generically, simvastatin has surpassed atorvastatin (Lipitor) as the best selling statin. As such, it is probably the most common cause of statin-induced myopathy, which is often a result of drug interactions.

Peptic ulcers caused by treatment with nonsteroidal anti-inflammatory drugs (NSAIDs) are mainly gastric ulcers. The greater the number of office visits and the longer the counseling time, the higher the smoking cessation rates have been.

A reader expressed disappointment that our recent listing of “Some Warfarin Drug Interactions”1 did not include acetaminophen. Perhaps it should have. Acetaminophen can increase the anticoagulant effect of warfarin, particularly with continued use, but it does so inconsistently. The mechanism of this interaction has not been established, but may be related to an acetaminophen metabolite inhibiting vitamin K-epoxide reductase, the target for warfarin’s anticoagulant effect.2

Patient susceptibility varies, possibly on a genetic basis; occasional use of acetaminophen generally has little or no effect on the international normalized ratio (INR) in patients on chronic warfarin therapy, but in some, even a few grams of the drug may cause a dramatic increase in INR. One study in healthy subjects found no effect of acetaminophen 4 g per day for 2 weeks, while another study in patients with the same acetaminophen dose for the same period of time found a moderate increase in INR.3,4 It might be prudent to monitor INR in patients on chronic warfarin therapy more closely than usual when they take more than 2 g per day of acetaminophen for more than a few days.

1. Pharmacogenetic-based dosing of warfarin. Med Lett Drugs Ther 2008; 50:39.
2. HH Thijssen et al. Paracetamol (acetaminophen) warfarin interaction: NAPQI, the toxic metabolite of paracetamol, is an inhibitor of enzymes in the vitamin K cycle. Thromb Haemost 2004; 92:797.
3. D Kwan et al. The effects of acetaminophen on pharmacokinetics and pharmacodynamics of warfarin. J Clin Pharmacol 1999; 39:68.
4. I Mahe et al. Paracetamol: A haemorrhagic risk factor in patients on warfarin. Br J Clin Pharmacol 2005; 59:371.

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Warfarin sodium (Coumadin, and others) and other coumarin anticoagulants prevent thrombosis, but patient response is highly variable and overanticoagulation can lead to hemorrhage. Genotyping patients for single nucleotide polymorphisms (SNPs) that affect coumarin metabolism and sensitivity may help clinicians estimate the therapeutic warfarin dose. The FDA has added a note to warfarin labeling recommending lowrange doses for patients with such genetic variations. Commercial tests for these variants are now available and cost about $500 per test.

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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The drugs of choice for treatment of some fungal infections are listed in the tables. Some of the indications and dosages recommended here have not been approved by the FDA. Other guidelines are available from the Infectious Diseases Society of America (www.idsociety.org).

Transdermal, transvaginal and intrauterine hormone delivery systems have made highly effective contraceptive products more convenient to use. New oral contraceptive options include regimens with fewer or shorter hormone-free intervals.

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.

Even though the incidence continues to decline, tuberculosis (TB) is still a problem in the United States. Treatment of TB can be divided into treatment of latent infection and treatment of active disease. Atable listing the first-line drugs used for treatment of TB with their doses and adverse effects can be found on page 16. Other guidelines with more detailed management recommendations are available.

Methicillin-resistant Staphylococcus aureus (MRSA) infections, which have been a concern for many years, previously occurred primarily in hospitalized patients and those recently treated with antibiotics. In the past few years, there has been an increasing incidence worldwide of community-associated (CA) MRSA infections in patients without recent antibiotic exposure or contact with the healthcare system.

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.

Tipranavir (Aptivus - Boehringer Ingelheim), a new protease inhibitor, has received accelerated approval from the FDA. It must be given with ritonavir (Norvir). The combination is indicated for use with other antiretrovirals to treat HIV infection in highly treatment-experienced adults who have ongoing viral replication or in those with HIV strains known to be resistant to multiple protease inhibitors.

The Medical Letter reported last year that sildenafil (Viagra - Pfizer) appeared to be effective for idiopathic pulmonary arterial hypertension (PAH), but confirmation from a controlled trial was needed. Now the results of such a study are about to be published, and the drug has been approved by the FDA for this indication under the trade name Revatio.

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.

Erlotinib (Tarceva) is the second oral epidermal growth factor receptor (EGFR) inhibitor to become available in the US for treatment of advanced refractory NSCLC. In clinical trials, erlotinib produced a response rate of only 8.9%, but increased median survival from 4.7 to 6.7 months. Patients who had never smoked and those with EGFR-positive tumors survived longer. Erlotinib is generally well tolerated; diarrhea and rash are the most common adverse effects.

An extended-release formulation of carbamazepine, available since 1997 for treatment of epilepsy, has now been approved under a new name, Equetro, for acute mania and mixed episodes of bipolar disorder. Although the drug was effective in some patients for up to 6 months, it has not been approved for maintenance treatment. Carbamazepine has not been shown to be more effective than lithium or valproate, and it can cause serious adverse effects.

The drugs of choice for treatment of some fungal infections are listed in the table that begins on page 8. Some of the indications and dosages recommended here have not been approved by the FDA.

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).

Telithromycin (Ketek - Aventis) has been approved by the FDA for oral treatment of mild to moderate community-acquired pneumonia, acute exacerbations of chronic bronchitis and acute bacterial sinusitis in patients age 18 and older. The drug is the first in a new class of antibiotics, the ketolides, derived from the macrolide erythromycin. Telithromycin has been marketed in Europe since 2001.

Parasitic infections are found throughout the world. With increasing travel, immigration, use of immunosuppressive drugs and the spread of AIDS, physicians anywhere may see infections caused by previously unfamiliar parasites. The table below lists first-choice and alternative drugs for most parasitic infections. The brand names and manufacturers of the drugs are listed in this article.

In recent years, several new contraceptive options have become available in the United States. Novel hormone delivery systems such as transdermal, transvaginal and intrauterine devices have improved the convenience of highly effective contraceptive products. Like oral contraceptives and most barrier contraceptives, these devices do not protect against sexually transmitted diseases.

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.

Daptomycin (Cubicin - Cubist), a cyclic lipopeptide (a new class of antibiotics), has been approved by the FDA for intravenous (IV) treatment of complicated skin and skin structure infections. It is being promoted as a once-daily bactericidal alternative to vancomycin (Vancocin, and others) for methicillin-resistant Staphylococcus aureusinfections.

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).

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.

A fixed-dose combination of atovaquone and proguanil hydrochloride has been approved by the FDA for oral prophylaxis and treatment of malaria due to Plasmodium falciparum, including choloroquine-resistant strains.

Mifepristone (RU 486; Mifeprex - Danco), an antiprogestin, has been approved by the FDA for termination of intrauterine pregnancies of 49 days or less. It is generally used with misoprostol (Cytotec - Searle), an E₁ prostaglandin analog marketed in the USA only for prevention of gastric ulcers.

Two types of oral contraceptives are available in the USA: combination oral contraceptives that contain both an estrogen and a progestin, and progestin-only contraceptives, or "mini-pills."Used as directed, all oral contraceptives marketed in the USA are similarly effective in preventing pregnancy.

Zaleplon, a pyrazolopyrimidine hypnotic, was recently approved by the FDA for short-term treatment of insomia. Zaleplon, like zolpidem, is a non-benzodiazepine that binds to benzodiazepine receptors.

Amprenavir is the fifth protease inhibitor to become available for treatment of HIV infection. It was approved by the FDA for use with other drugs in the treatment of HIV-infected adults and children at least four years old.

Rofecoxib, a selective COX-2 inhibitor, has been approved by the FDA for treatment of osteoarthritis, acute pain and menstrual pain.

Reports of adverse interactions between drugs continue to accumulate. Recently, the FDA has expanded the recommendations on drug interactions found in the package inserts of new drugs.

Leflunomide (Arava - Hoechst Marion Roussel), which inhibits pyrimidine synthesis, and etanercept (Enbrel - Immunex/Wyeth-Ayerst), which blocks the action of tumor necrosis factor (TNF), have been approved by the FDA for treatment of rheumatoid arthritis. A third drug, infliximab (Remicade - Centocor), which also blocks TNF and has been used to treat rheumatoid arthritis, was approved earlier for treatment of Crohn's disease. Its use in Crohn's disease will be reviewed in a future issue.

Carvedilol (Coreg - SmithKline Beecham and Boehringer-Mannheim), a betaadrenergic and alpha-adrenergic blocker approved by the FDA for treatment of hypertension in 1995, but not marketed at that time, has now been approved and marketed for treatment of mild or moderate (NYHA class II or III) heart failure stabilized on other drugs. It is being promoted as an add-on drug that reduces the morbidity and mortality of the disease.

The drugs of choice for treatment of deep fungal infections are listed in the table below. Some of the indications and dosages recommended here have not been approved by the FDA.

The US Food and Drug Administration (FDA) has approved the marketing of five new drugs for treatment of HIV Infection. Stavudine (D4T; Zerit - Bristol-Myers Squibb) and lamivudine (3TC; Epivir - Glaxo Wellcome) are nucleoside analogs similar to zidovudine (AZT), didanosine (ddl) and zalcitabine (ddC). Saquinavir (Invirase - Roche), ritonavir (Norvir - Abbott) and indinavir (Crixivan - Merck) are protease inhibitors, a new class of anti-HIV drugs.

The drugs of choice for treatment of deep fungal infections are listed in the table on page 101. Some of the indications and dosages recommended here have not been approved by the US Food and Drug Administration. More detailed guidelines are available from the Infectious Diseases Society of America (J Sobel et al, Clin Infect Dis, volume 30, April 2000).

Itraconazole (Sporanox - Janssen), an oral antifungal triazole that has been available in the USA since 1992 for treatment of deep fungal infections (Medical Letter, 35:7, 1993), is now being marketed for treatment of dermatophyte infections of the toenails, with or without fingernail involvement.

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).

Methadone, an opioid agonist that can be taken orally, has been used for maintenance treatment for many years in the USA (DM Novick et al, Drug Alcohol Depend, 33:235, 1993). Last year, the US Food and Drug Administration approved the distribution and use of L-alpha-acetyl-methadol (LAAM; ORLAAM - Bio Development Corporation, McLean, VA), a long-acting congener of methadone. LAAM, like methadone, will be available for this indication only through federal and state-regulated treatment programs.

Fluvastatin (Lescol - Sandoz), an HMG-CoA reductase inhibitor, was recently marketed in the USA for treatment of hypercholesterolemia. A synthetic mevalonolactone derivative, it is chemically distinct from previously available drugs in this class.

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).

Rifabutin (formerly ansamycin; Mycobutin - Adria), a rifamycin antibiotic similar to rifampin (Rifadin, Rimactane) was recently approved by the US Food and Drug Administration for prevention of disseminated Mycobacterium avium complex (MAC) disease in patients with advanced HIV infection.

Itraconazole (Sporanox - Janssen), an antifungal triazole, has been approved by the US Food and Drug Administration (FDA) for oral treatment of histoplasmosis and blastomycosis. These two endemic mycoses occur both in normal hosts and in immunocompromised patients, such as those with AIDS (RW Bradsher, Clin Infect Dis, 14:S82, 1992; LJ Wheat, Clin Infect Dis, 14:S91, 1992).

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).

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.

After many years of decline, the incidence of tuberculosis has recently increased because the disease occurs in patients with AIDS (Morbid Mortal Weekly Rep, 36:817, Jan 1, 1988). For uncomplicated tuberculosis, the recent trend in tuberculosis treatment has been toward a shorter period of therapy and increased use of pyrazinamide.