title: Multiple-dose pharmacokinetics of rimantadine in elderly adults.
abstract: To assess the possible effect of aging on rimantadine hydrochloride pharmacokinetics, single- and multiple-dose kinetics were determined in 18 healthy adults with ages between 51 and 79 years. Subjects ingested single 100-mg oral doses of rimantadine after an overnight fast, followed after 5 days by a dosage of 100 mg twice a day for 9.5 days. No differences were observed among the age-stratified groups in measured or derived pharmacokinetic parameters. Peak concentrations in plasma (mean +/- standard deviation) following the single- and multiple-dose regimens, respectively, were 89 +/- 25 and 417 +/- 129 ng/ml for subjects who were 50 to 60 years of age (group 1), 92 +/- 24 and 401 +/- 84 ng/ml for those 61 to 70 years of age (group 2), and 100 +/- 14 and 538 +/- 51 for those 71 to 79 years of age (group 3). The elimination half-life in plasma following multiple doses averaged 33.5 h for group 1, 32.5 h for group 2, and 38.6 h for group 3. Steady-state concentrations in nasal mucus developed by day 5 of dosing (1.5-fold higher than concentrations in plasma), and rimantadine remained detectable in secretions for 5 days after the last dose in 65% of subjects. Stepwise regression analysis suggested that changes in maximum concentration in plasma and area under the concentration-time curve at steady state may be related to creatinine clearance. The results indicate that no important differences in rimantadine multiple-dose pharmacokinetics exist among healthy elderly adults with ages between 51 and 79 years.
authors.affiliation: Department of Internal Medicine, University of Virginia School of Medicine, Charlottesville 22908.
authors.forename: R L
authors.initials: RL
authors.lastname: Tominack
authors.forename: R J
authors.initials: RJ
authors.lastname: Wills
authors.forename: L E
authors.initials: LE
authors.lastname: Gustavson
authors.forename: F G
authors.initials: FG
authors.lastname: Hayden
mesh_terms: D000218:Adamantane / Q000031:analogs & derivatives*; D000284:Administration, Oral; D000367:Age Factors; D000368:Aged; D000375:Aging / Q000378:metabolism*; D004334:Drug Administration Schedule; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012299:Rimantadine / Q000008:administration & dosage / Q000009:adverse effects / Q000493:pharmacokinetics*
chemical_list: D012299:Rimantadine; D000218:Adamantane