Cilostazol, a phosphodiesterase III inhibitor that has been used in Japan since 1988, has been approved by the FDA for treatment on intermittent claudication due to occlusive peripheral arterial disease.

The FDA has approved an extended-release (XR) formulation of the benzodiazepine alprazolam (Xanax XR - Pfizer) for treatment of panic disorder, with or without agoraphobia. The new formulation is intended to reduce the need for frequent dosing and problems of interdose anxiety. This review describes the effectiveness of the extended-release formulation, as well as sections on dependence, abuse and withdrawal, adverse effects, and drug interactions. The review concludes with an overall assessment of the drug's efficacy and cost.

The FDA has approved the marketing of fentanyl sublingual tablets (Abstral – ProStrakan) for treatment of breakthrough pain in adult cancer patients who are already receiving and are tolerant to opioid therapy. It is the fourth transmucosal formulation of fentanyl to become available in the US for this indication.1-3The manufacturer recommends an initial dose of 100 mcg, a maximum of 2 doses per breakthrough pain episode, and use for no more than 4 breakthrough pain episodes per day. As with all formulations of fentanyl, strong inhibitors of CYP3A4 such as clarithromycin (Biaxin, and others)...

Alfuzosin hydrochloride (Uroxatral - Sanofi-Synthelabo) is now available in the US in a new formulation for once-daily treatment of benign prostatic hyperplasia (BPH). The drug has been used in Europe since 1987. Alpha₁-blockers cause relaxation of smooth muscle tone in the bladder neck, prostatic capsule and prostatic urethra, relieving symptoms of urinary obstruction.

Tadalafil (Cialis - Lilly Icos) is the third oral drug to be approved by the FDA for treatment of erectile dysfunction. It has a longer duration of action than sildenafil (Viagra) or vardenafil (Levitra - Medical Letter 2003; 45:77).

View Table: Mechanisms of Drug Interactions

Imatinib mesylate (STI-571; Gleevec - Novartis), an oral tyrosine kinase inhibitor, has received accelerated approval from the FDA for treatment of all phases of chronic myeloid leukemia (CML) after interferon has failed.

Aripiprazole (Abilify - Bristol-Myers Squibb/Otsuka), a quinolinone derivative, has been approved by the FDA for treatment of schizophrenia.

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.

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.