The FDA has approved nasal spray formulations of the benzodiazepines diazepam (Valtoco — Neurelis) and midazolam (Nayzilam — UCB) for acute treatment of intermittent episodes of frequent seizure activity (seizure clusters). Diazepam rectal gel (Diastat, Diastat AcuDial, and generics) has been used for this indication for many years.

Tizanidine (Zanaflex - Athena Neurosciences) has been approved by the US Food and Drug Administration for oral treatment of increased muscle tone associated with spasticity. It has been available in Europe and Japan for 12 years as a short-term muscle relaxant.

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.

Loratadine (Claritin - Schering), a new H 1 -receptor antagonist, has been approved by the U.S. Food and Drug Administration for treatment of seasonal allergic rhinitis in patients more than 12 years old. It will compete with older, relatively sedating drugs such as chlorpheniramine (Chlor-Trimeton, and others) and clemastine (Tavist - Medical Letter, 35:9, 1993) and with newer relatively non-sedating agents such as terfenadine (Seldane) and astemizole (Hismanal).

Flumazenil (Mazicon - Roche), a benzodiazepine receptor antagonist, has been approved by the US Food and Drug Administration to reverse the sedative effects of benzodiazepines after anesthesia, sedation for brief surgical or diagnostic procedures, or after benzodiazepine overdosage. The drug does not antagonize opioids, non-benzodiazepine sedatives, or anesthetic drugs.

Acute toxic reactions to drugs of abuse continue to be important problems. Some patients may have mixed intoxications with complex combinations of signs and symptoms.

To avoid the morbidity and occasional mortality of transurethral resection or open prostatectomy, some urologists are now using balloon dilatation of the prostatic urethra to treat benign prostatic hypertrophy.

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.

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.