With the possibility that chemical weapons may be used against United States armed forces in the Persian Gulf, the military has taken steps to protect our troops against poison gas, particularly ''nerve agents';'; (MA Dunn and FR Sidell, JAMA, 262:649, 1989).

The recent attack in the Tokyo subway has led to many questions about the clinical effects, treatment and prevention of nerve gas poisoning.

Zaleplon, a pyrazolopyrimidine hypnotic, was recently approved by the FDA for short-term treatment of insomia. Zaleplon, like zolpidem, is a non-benzodiazepine that binds to benzodiazepine receptors.

The FDA now requires boxed warnings in the package inserts of benzodiazepines describing the potential for these drugs to be abused and misused and to cause addiction and physical dependence. Benzodiazepine labels have contained a boxed warning about a risk of serious drug interactions with opioids since 2016.

Since The Medical Letter last reviewed the choice of benzodiazepines (Volume 23, page 41, 1981), several new drugs have been marketed and some old ones are now available generically. Most of the benzodiazepines available for oral use in the USA are listed in the table on page 28.

Modafinil (Provigil - Cephalon; Alertec - Draxis in Canada), first approved by the FDA in 1999 for treatment of excessive daytime sleepiness associated with narcolepsy (Medical Letter 1999; 41:30), has now also been approved for treatment of patients with excessive sleepiness due to obstructive sleep apnea/hypopnea syndrome (OSAHS) or shift work sleep disorder (SWSD) (DSM-IV, text revision, Washington, DC: American Psychiatric Association, 2000, page 622).

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.

Pantoprazole, the fourth benzimidazole proton pump inhibitor to become available in the United States, has been marketed for short-term oral treatment of erosive gastroesophageal reflux disease (GERD).

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.

The FDA has approved suvorexant (Belsomra – Merck), the first orexin receptor antagonist to become available in the US, for treatment of sleep-onset and/or sleep-maintenance insomnia.