The FDA has approved emtricitabine/tenofovir (Truvada - Gilead) and abacavir/lamivudine (Epzicom - GSK), two new fixed-dose combinations of nucleoside/nucleotide reverse transcriptase inhibitors (NRTIs), for once-daily use in treatment of HIV infection. Two other fixed-dose NRTI combinations were previously approved for twice-daily dosing. Dual NRTI therapy is generally used in either an NNRTI (non-nucleoside reverse transcriptase inhibitor)-based or a PI (protease inhibitor)-based regimen.

Angiotensin receptor blockers (ARBs) are widely used as an alternative to angiotensin converting enzyme (ACE) inhibitors for treatment of hypertension because they lower blood pressure without inducing a cough. It has not been established that they provide the same cardiac benefits as ACE inhibitors. Recently, an editorial in the British Medical Journal suggested that ARBs may increase the risk of myocardial infarction.

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 recently cleared the AmpliChip CYP450 Test (Roche), which analyzes blood-derived DNA to detect genetic variations in the activity of cytochrome P450 (CYP) enzymes CYP2D6 and CYP2C19 and determines the metabolizer status of the patient. The test is intended to help guide clinicians in prescribing individualized drug therapy. About 25% of all drugs, including many antidepressants and antipsychotics, are substrates of either CYP2D6 or CYP2C19. The test is being promoted initially to psychiatrists.

The physiologic changes that occur with aging can affect the pharmacokinetics and pharmacodynamics of many prescription and over-the-counter drugs, increasing the likelihood of adverse effects.

Hyperphosphatemia in end-stage renal disease can lead to secondary hyperparathyroidism, renal osteodystrophy, metastatic calcification and cardiovascular mortality. addition to dietary restriction of phosphorus and hemodialysis, drugs that bind phosphates in the gut are usually needed as well. Aluminum hydroxide is no longer recommended for long-term use because of concerns about its toxicity.

Rituximab (Rituxan - Genentech), an anti-CD20 monoclonal antibody already marketed for treatment of B-cell non-Hodgkin's lymphoma, is now FDA-approved for use concurrently with methotrexate to treat moderate to severe rheumatoid arthritis in patients who have had an inadequate response to one or more tumor necrosis factor (TNF) inhibitors. Rituximab selectively depletes CD20+ B cells, which apparently play a role in the autoimmune response and in the chronic synovitis associated with rheumatoid arthritis.

The FDA has approved a new genetic test to identify patients who may be at increased risk of severe toxicity when treated with the cancer chemotherapy drug irinotecan (Camptosar). The Invader UGT1A1 Molecular Assay (Third Wave Technologies) detects the UGT1A1*28 allele, a variation in the uridine diphosphate glucuronosyltranferase 1A1 (UGT1A1) gene. The FDA recently revised the safety labeling for irinotecan, recommending that the dosing of irinotecan be reduced for patients who are homozygous for the UGT1A1*28 allele.

The FDA has approved the marketing of extended release (ER) ranolazine (Ranexa - CV Therapeutics) for treatment of chronic angina in patients who have not achieved an adequate response with other antianginal drugs. It should be used in combination with a nitrate, a beta-blocker or the dihydropyridine calcium-channel blocker amlodipine (Norvasc), and appears to be more effective in men. The labeling for ranolazine specifies amlodipine as the calcium-channel blocker of choice because the use of other dihydropyridines with ranolazine has not been studied, and use with diltiazem (Cardizem, and...

The US manufacturer of varicella zoster immune globulin (VZIG; Massachusetts Public Health Biologic Laboratories, Boston, MA) recently discontinued its production. A Canadian formulation, VariZIG (Varicella Zoster Immune Globulin [Human] - Cangene Corporation, Winnipeg) is now available in the US under an investigational new drug application expanded access protocol.