Pharmacokinetics and pharmacodynamics of diphenhydramine 25 mg in young and elderly volunteers.
Thirty-seven young and elderly male and female volunteers 21 to 76 years of age received a single 25-mg oral dose of diphenhydramine or matching placebo in a double-blind, randomized, two-way crossover study. Plasma diphenhydramine concentrations, self-ratings of sedation, mood, and autonomic effects, performance on the digit-symbol substitution test (DSST), and heart rate were determined for 24 hours after administration. Information acquisition and recall were tested at 2.5 and 24 hours after administration. Age and gender did not significantly influence diphenhydramine peak plasma concentration, time of peak concentration, elimination half-life, area under the plasma concentration curve, or apparent oral clearance. Effects on psychomotor performance, sedation, mood, and memory did not differ between diphenhydramine and placebo in either group. Thus, the pharmacokinetics of single 25-mg oral doses of diphenhydramine are not influenced by age or gender. This dose of diphenhydramine produces essentially undetectable pharmacodynamic effects in both the young and elderly.
Department of Pharmacology and Experimental Therapeutics, Tufts University School of Medicine, New England Medical Center Hospital, Boston, Massachusetts 02111, USA.
J M
JM
Scavone
D J
DJ
Greenblatt
J S
JS
Harmatz
N
N
Engelhardt
R I
RI
Shader
D000328:Adult; D000367:Age Factors; D000368:Aged; D018592:Cross-Over Studies; D004155:Diphenhydramine / Q000493:pharmacokinetics* / Q000494:pharmacology; D004311:Double-Blind Method; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006634:Histamine H1 Antagonists / Q000493:pharmacokinetics* / Q000494:pharmacology; D006801:Humans; D006993:Hypnotics and Sedatives / Q000493:pharmacokinetics* / Q000494:pharmacology; D008297:Male; D008875:Middle Aged; D012737:Sex Factors
D006634:Histamine H1 Antagonists; D006993:Hypnotics and Sedatives; D004155:Diphenhydramine