Donepezil hydrochloride (Aricept - Eisai), a piperidine-based acetylcholinesterase inhibitor, is now being marketed for oral treatment of cognitive symptoms in patients with mild to moderate dementia due to Alzheimer's disease. Donepezil is the second drug approved for this indication; tacrine hydrochloride (Cognex), also an acetylcholinesterase inhibitor, has been available in the USA for four years (Medical Letter, 35:87, 1993).

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.

Candesartan cilexetil (Atacand - Astra) is the fourth angiotensin II receptor antagonist to become available in the USA for oral treatment of hypertension.

Citalopram hydrobromide (Celexa - Forest/Parke-Davis), a selective serotonin reuptake inhibitor (SSRI) available in Europe since 1989, has now been approved by the US Food and Drug Administration (FDA) for treatment of depression. It is being advertised as having a 'favorable side-effect profile.'

Rivastigmine tartrate (Exelon - Novartis), a carbamate-based cholinesterase inhibitor, is now being marketed for treatment of patients with dementia due to Alzheimer's disease.

Rabeprazole, a benzimidazole proton pump inhibitor similar to omeprazole and lansoprazole, has been approved by the FDA for treatment of duodenal ulcers, healing and maintenance treatment of erosive or ulcerative gastroesophageal reflux disease, and for long-term treatment of chronic hypersecretory conditions, including Zollinger-Ellison syndrome

Even though its effectiveness has not been established, many patients take St. John's Wort (Hypericum perforatum), an over-the-counter herbal extract, to treat symptoms of depression, often without the knowledge of their physicians. Recent reports indicate that St. John's wort interacts adversely with a number of drugs.

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.

Colesevelam hydrochloride (Welchol - Sankyo Pharma), a nonabsorbed hydrophilic polymer that binds bile acids, has been approved by the FDA for reduction of plasma LDL cholesterol in patients with primary hypercholesterolemia.

Trospium chloride (Sanctura - Indevus/Odyssey) has been approved by the FDA for treatment of overactive bladder with symptoms of urge urinary incontinence, urgency and urinary frequency. It has been available in Europe for many years.