Many prescriptions for eye drops call for instillation of 1-2 drops. But Medical Letter consultants in ophthalmology seem to agree that all eye drops should generally be given in doses of only one drop. The volume of a single drop can vary with the viscosity of the solution, the design of the dropper, and patient technique. The average volume of a drop is 35-50 microliters, but can be as high as 75 microliters. An eye brimming with fluid holds 30 microliters at best, so even one drop is often an overdose. A second either washes out the first or increases the possibility of systemic toxicity,...

Rotigotine (Neupro - Schwarz Pharma), a nonergot dopamine agonist in a transdermal patch formulation, was recently approved by the FDA for treatment of early Parkinson's disease (PD).

The US Preventive Services Task Force (USPSTF) has recently concluded that available evidence is insufficient to assess the balance between potential benefits and harms of using the prostate-specific antigen (PSA) to screen men < 75 years old for prostate cancer and has recommended against screening men > 75 years old.

Topiramate (Topamax - Ortho-McNeil) has been approved by the US Food and Drug Administration (FDA) for oral use as an adjunct to other drugs in adult patients with partial seizures. Since this diagnostic category includes the largest number of patients with refractory epilepsy, new drugs with antiepileptic activity are usually tried first for this indication. Topiramate (toe pyre' a mate) is a structurally unique agent chemically related to the D-enantiomer of fructose.

Modafinil (Provigil), a benzhydryl sulfinylacetamide non-amphetamine stimulant that has been used in Europe since 1995, has now been approved by the FDA for treatment of excessive daytime sleepiness associated with narcolepsy.

Fexofenadine (fex oh fen' a deen) hydrochloride (Allegra - Hoechst Marion Roussel) has been approved by the US Food and Drug Administration for treatment of seasonal allergic rhinitis. An active metabolite of terfenadine, fexofenadine is being heavily advertised as "nonsedating...without 'black box' warnings."

Venlafaxine hydrochloride (Effexor - Wyeth-Ayerst) was recently approved by the US Food and Drug Administration for treatment of depression. An aminomethyl-benzyl- cyclohexanol, it is chemically related to bupropion (Wellbutrin).

Zileuton (zye loo' ton; Zyflo - Abbott), an inhibitor of leukotriene synthesis, has been approved by the US Food and Drug Administration (FDA) for prophylaxis and maintenance treatment of chronic asthma in adults and children more than 12 years old. A related drug—zafirlukast (Accolate), a leukotriene receptor antagonist—was recently reviewed in the Medical Letter (vol. 38, page 111, December 20, 1996). Neither of these drugs is recommended for treatment of acute asthma.

A once-weekly transdermal formulation of the acetylcholinesterase inhibitor donepezil (Adlarity – Corium) has been approved by the FDA for treatment of mild, moderate, and severe Alzheimer's disease (AD) dementia. Donepezil is the second acetylcholinesterase inhibitor to become available in a transdermal formulation; transdermal rivastigmine (Exelon Patch), which is applied once daily, has been available for years for the same indication. Donepezil is also available in oral formulations (Aricept, and generics) for treatment of AD dementia.

Grepafloxacin (Raxar - Glaxo Wellcome), a once-daily oral fluoroquinolone, is now being marketed for treatment of community-acquired pneumonia, acute bacterial exacerbations of chronic bronchitis, uncomplicated gonorrhea, and nongonococcal urethritis and cervicitis.