Sex- and dose-dependency in the pharmacokinetics and pharmacodynamics of (+)-methamphetamine and its metabolite (+)-amphetamine in rats

• Published in: Toxicology and applied pharmacology Vol. 209; no. 3; pp. 203 - 213
• Main Authors: Milesi-Hallé, Alessandra, Hendrickson, Howard P., Laurenzana, Elizabeth M., Gentry, W. Brooks, Owens, S. Michael
• Format: Journal Article
• Language: English
• Published: San Diego, CA Elsevier Inc 15.12.2005; Elsevier
• Subjects: (+)-Amphetamine; (+)-Methamphetamine; 60 APPLIED LIFE SCIENCES; AMP; Amphetamine - metabolism; Amphetamine - pharmacokinetics; AMPHETAMINES; Animals; Area Under Curve; Biological and medical sciences; Central Nervous System Stimulants - metabolism; Central Nervous System Stimulants - pharmacokinetics; Chromatography, Liquid; Dose-dependency; Dose-Response Relationship, Drug; Female; Half-Life; Humans; Locomotion; Male; Medical sciences; Metabolic Clearance Rate; Methamphetamine - metabolism; Methamphetamine - pharmacokinetics; Motor Activity - drug effects; Pharmacokinetics; RATS; Rats, Sprague-Dawley; RENAL CLEARANCE; SEX DEPENDENCE; Sex Factors; Sex-dependency; Spectrometry, Mass, Electrospray Ionization; Stereotyped Behavior - drug effects; Tissue Distribution; Toxicology; URINE; Locomotion; Sex-dependency; (+)-Methamphetamine; (+)-Amphetamine; Rats; Pharmacokinetics; Dose-dependency; Amphetamine derivatives; Rat; CNS stimulant; Metabolite; Psychotropic; Rodentia; Metamfetamine; Sex; Sympathomimetic; Vertebrata; Mammalia; Animal; Amfetamine; Dose
• ISSN: 0041-008X; 1096-0333
• DOI: 10.1016/j.taap.2005.04.007

These studies investigated how (+)-methamphetamine (METH) dose and rat sex affect the pharmacological response to METH in Sprague–Dawley rats. The first set of experiments determined the pharmacokinetics of METH and its pharmacologically active metabolite (+)-amphetamine (AMP) in male and female Sprague–Dawley rats after 1.0 and 3.0 mg/kg METH doses. The results showed significant sex-dependent changes in METH pharmacokinetics, and females formed significantly lower amounts of AMP. While the area under the serum concentration–time curve in males increased proportionately with the METH dose, the females showed a disproportional increase. The sex differences in systemic clearance, renal clearance, volume of distribution, and percentage of unchanged METH eliminated in the urine suggested dose-dependent pharmacokinetics in female rats. The second set of studies sought to determine the behavioral implications of these pharmacokinetic differences by quantifying locomotor activity in male and female rats after saline, 1.0, and 3.0 mg/kg METH. The results showed sex- and dose-dependent differences in METH-induced locomotion, including profound differences in the temporal profile of effects at higher dose. These findings show that the pharmacokinetic and metabolic profile of METH (slower METH clearance and lower AMP metabolite formation) plays a significant role in the differential pharmacological response to METH in male and female rats.