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

Sotalol (hydrochloride (Betapace -Berlex; Sotacor -Bristol Laboratories of Canada), an antiarrhythmic drug that prolongs repolarization (Class III) and also has beta-adrenergic-blocking activity (Class II), was recently approved by the US Food and Drug Administration (FDA) for oral treatment of life-threatening ventricular arrhythmias.

An extended-release formulation of the centrally-acting muscle relaxant cyclobenzaprine (Amrix - Cephalon) has been approved by the FDA for treatment of muscle spasms. Immediate-release (IR) cyclobenzaprine (Flexeril, and others) has been available since 1977.

The FDA has approved an oral extended-release formulation of gepirone (Exxua – Fabre-Kramer), a selective 5-HT_1A receptor agonist, for treatment of major depressive disorder (MDD) in adults. Gepirone was originally developed decades ago for treatment of anxiety and depression, but it was not approved by the FDA for such use. Gepirone is structurally related to buspirone, which is FDA-approved for treatment of anxiety.

Paroxetine (Paxil - SmithKline Beecham), a new selective serotonin reuptake inhibitor (SSRI), is now available in the USA. Two other SSRIs, fluoxetine (Prozac - Medical Letter, 30:45, 1988; 32:83, 1990) and sertraline (Zoloft - Medical Letter, 34:47, 1992), were approved previously.

Older patients are especially susceptible to drug-induced cognitive impairment. They are more likely to be taking multiple drugs, to have higher blood levels of those drugs because of renal or hepatic dysfunction, and to have pre-existing cognitive problems that make it difficult to detect the role of drugs causing new symptoms or making old ones worse.

Bupropion (Wellbutrin - Burroughs Wellcome) was recently marketed in the USA for treatment of depression. First approved by the Food and Drug Administration in late 1985, the drug was withdrawn from the market in early 1986 because of a high incidence of seizures in one study.

The FDA has approved the oral GABA_A receptor modulator zuranolone (Zurzuvae – Sage Therapeutics/Biogen) for treatment of postpartum depression (PPD). Zuranolone is the second drug to be approved for this indication; brexanolone (Zulresso), another GABA_A receptor modulator, was approved for IV treatment of PPD in 2019.

Dofetilide (Tikosyn - Pfizer), a new methanesulfonamide antiarrhythmic drug, has recently been marketed for oral treatment of atrial fibrillation and flutter.

The FDA has approved lemborexant (Dayvigo – Eisai), an orexin receptor antagonist, for treatment of sleep-onset and/or sleep-maintenance insomnia in adults. It is the second orexin receptor antagonist to be approved for this indication; suvorexant (Belsomra) was the first.