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.

Atovaquone (Mepron - Burroughs Wellcome), a hydroxynaphthoquinone, was recently approved by the US Food and Drug Administration (FDA) for oral treatment of mild to moderate Pneumocystis carinii pneumonia (PCP) in patients who cannot tolerate trimethoprim-sulfamethoxazole (Septra, Bactrim, and others). PCP is a common opportunistic infection and frequent cause of death in patients with AIDS.

As the weather becomes warmer, physicians may see more photosensitivity reactions due to systemic or topical drugs, perfumes, cosmetics or sunscreens. Even brief exposure to sunlight in warm or cold weather can cause intense cutaneous reactions in patients with drug-induced photosensitivity, and some patients may continue to be sensitive to sunlight long after stopping use of the offending agent.

Many commonly used drugs can interfere with sexual function in both men and women, causing loss of libido, interfering with erection or ejaculation in men, and delaying or preventing orgasm in women. Drug-related effects on sexual function may be difficult to distinguish from the effects of depression or disease, but most are reversible when drug use is stopped and sometimes when dosage is decreased. Since many patients are reluctant to talk about sexual difficulties, physicians may wish to ask about the possibility of drug-induced sexual dysfunction, particularly when they have...

The FDA has approved artemether-lumefantrine (Coartem - Novartis) for oral treatment of uncomplicated Plasmodium falciparum malaria. It is not approved for prophylaxis. Artemether-lumefantrine is the first artemisinin-based drug approved for use in the US. Artemisinins are Chinese herbal products used worldwide to treat malaria. The intravenous formulation of artesunate, another artemisinin, is available in the US through the CDC.

The FDA has approved pitolisant (Wakix – Harmony), a histamine-3 (H₃)-receptor antagonist/inverse agonist, for treatment of excessive daytime sleepiness (EDS) or cataplexy in adults with narcolepsy. It is the first H₃-receptor antagonist/inverse agonist to become available in the US and the first non-controlled substance to receive FDA approval for these indications. Pitolisant has been available in Europe since 2016.