Pharmacokinetics of meptazinol after single and multiple oral administration to elderly patients

Oral administration of meptazinol (200 mg Meptid) to male and female geriatric patients (greater than 70 years) resulted in rapid absorption, with peak drug concentrations at 0.5 to 3 h after dosage. Subsequent elimination also proceeded rapidly with a half-life of 3.39 h (+/- 0.26 SEM) after a single dose and 4.97 h (+/- 0.80 SEM) after 13 consecutive 6-h doses. These values were not statistically different. There was no accumulation of meptazinol above that expected from the single-dose kinetics. Plasma protein binding of meptazinol was 33.8% (+/- 0.74 SEM). No sex difference was apparent in any of the pharmacokinetic parameters determined. Comparison of these results with those obtained in an earlier study in young volunteers showed that although the half-life of meptazinol was somewhat longer than the value of 2 h seen in the young, peak plasma concentrations after single and multiple dosing were similar for both age groups, implying that clearance remained largely unaltered. It was concluded that there was no pharmacokinetic basis for recommending a reduction in dosage when treating elderly patients with oral meptazinol.