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.

Eplerenone (e pler' en one; Inspra - Pharmacia), an aldosterone receptor antagonist similar to spironolactone (Aldactone, and others), has been approved by the FDA, but not yet marketed, for treatment of hypertension. It has also been tried for treatment of heart failure.

View the Inhibitors and Inducers of CYP Enzymes, P-Glycoprotein, and Other Transporters tables

The FDA has approved Prestalia (Symplmed), an oral fixed-dose combination of the dihydropyridine calcium channel blocker amlodipine (Norvasc, and generics) and a new salt form of the angiotensin-converting enzyme (ACE) inhibitor perindopril, for treatment of hypertension in patients not adequately controlled on monotherapy or already taking both drugs, and in those just starting therapy who are likely to need multiple drugs to control their blood pressure. The new salt form (perindopril arginine) is more stable and has a longer shelf-life than perindopril erbumine (Aceon, and...

The FDA has approved mavacamten (Camzyos – MyoKardia/BMS), a modulator of cardiac myosin, to improve functional capacity and symptoms in adults with New York Heart Association (NYHA) class II or III obstructive hypertrophic cardiomyopathy (HCM) who have a baseline left ventricular ejection fraction (LVEF) ≥55%. Mavacamten is the first drug in its class to become available in the US.

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 announced changes in the labeling of simvastatin to reduce the risk of myopathy. These changes include limiting the use of the 80-mg maximum dose to patients who have been taking it for 12 months or more without evidence of myopathy and new recommendations for use of simvastatin with other drugs. Simvastatin is available alone (Zocor, and others) and in combination with ezetimibe (Vytorin) and with niacin (Simcor).

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Eletriptan hydrobromide (Relpax Pfizer) is now available in the US for oral treatment of migraine headache in adults. It is the seventh serotonin 5-HT1B/1D-receptor agonist (triptan) to be approved by the FDA for this indication. This review describes the pharmacokinetics, adverse effects, drug interactions and recommended dosage of eletriptan. Clinical trials comparing the new drug to placebo and to sumatriptan are presented. A dosage and cost table for all the triptans available in the US is also included. The review concludes with an overall assessment of eletriptan's efficacy and...

Bepridil hydrochloride (Vascor - McNeil Pharmaceutical/Wallace Laboratories), a calcium-channel blocking agent chemically unrelated to verapamil (Calan, and others), nifedipine (Procardia, and others), or other drugs in this class, was recently approved by the US Food and Drug Administration for oral treatment of chronic stable angina pectoris. Because of its potential adverse effects, the labeling recommends reserving the drug for patients who fail to respond optimally to or are intolerant of other antianginal agents.