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.

Several currently available antiemetic drugs can prevent vomiting caused by cancer chemotherapy. Anticancer drugs that cause vomiting are listed in the table below.

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.

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.

Alosetron hydrochloride (Lotronex - Glaxo Welcome), a selective serotonin receptor antagonist, has received FDA approval for treatment of irritable bowel syndrome (IBS) in women whose primary bowel symptom is diarrhea.

Millions of people now take herbal products and other "dietary supplements." The Physicians' Desk Reference has published a PDR for Herbal Medicines listing their ingredients and indications, and the Drug Topics Red Book lists their prices.

Anxiety disorders (generalized anxiety disorder, panic disorder, social anxiety disorder, and various phobias) are the most common form of psychiatric illness. They can be treated effectively with cognitive behavioral therapy (CBT) and/or pharmacotherapy.

Every pharmaceutical drug is a dose-dependent poison. This article describes the clinical presentation and treatment of some dangerous overdoses commonly reported in adults.

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...