Dose tolerance and pharmacokinetic studies of L (+) pseudoephedrine capsules in man

Abstract

Dose tolerance and pharmacokinetic studies of pseudoephedrine sustained action capsules were performed in thirty-three adult male subjects who received either 120 mg or 150 mg capsules every twelve hours for seven consecutive days in a double-blind parallel design study. Although only one subject in the 150 mg group was discontinued prematurely from this study, a large number of side effects typical of CNS stimulation were seen. A placebo effect might account for a portion of these complaints, however symptoms evaluated as being due to drug were significantly more severe and persistent in the 150 mg group. Pulse rates showed a persistent and significant increase while systolic and diastolic blood pressure fell from the baseline values in both groups. A pharmacokinetic analysis of the pseudoephedrine plasma concentration-time data provided estimates of half-life and the volume of distribution/availability ratio. The values obtained were in good agreement with values reported by others. Half-life was not influenced by urine pH probably as a result of the narrow range of urine pHs observed in the subjects. Calculations of relative bioavailability suggest that the 120 mg capsule formulation has a 30% greater bioavailability compared to the 150 mg capsule.

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“…Mean biological half-life was 5.9 ± 2.2 hours and mean steady state plasma concentration of (+)-pseudoephedrine 447 ± 116 ng/mL in the 120 mg group, these values were 6.9 ± 3.9 hours and 510 ± 133 ng/mL respectively in the 150 mg group. There was no correlation between the elimination half-life of (+)-pseudoephedrine and the severity or number of symptoms experienced by the subjects (Dickerson et al, 1978).…”

“…In addition, no change was observed between (-)-ephedrine hydrochloride given alone or in combination with theophylline or phenobarbitone. Dickerson et al (1978) assessed dose tolerance and pharmacokinetics of (+)-pseudoephedrine in a double-blind parallel study. Thirty-four healthy male volunteers were randomly assigned to groups receiving either a dose of 120 or 150 mg (+)-pseudoephedrine/person as sustained action capsule, taken every 12 hours for seven test days.…”

“…A double-blind parallel study design was used to assess tolerability and pharmacokinetics of (+)-pseudoephedrine (Dickerson et al, 1978). Thirty three healthy male volunteers were included in the study, and were randomly assigned to either a dose of 120 or 150 mg pseudoephedrine as sustained action capsule, taken every 12 hours for seven test days.…”

Effects of Pseudoephedrine in Man

“…Few side-effects were found although several complained of insomnia during the first 3 days of treatment. Dickerson et al (18) studied subjects who had taken either 120 mg or 150 mg pseudoephedrine in slow release capsules. They found rather more side-effects and also that the bioavailability of the 120 mg capsules seemed to be rather higher.…”

The effects of ephedrine on the development of fatigue in a prolonged driving-related task

“…In therapeutic doses, ephedrine causes CNS stimulation in some individuals, which is often manifested as restlessness and insomnia (Dickerson et al, 1978). Ephedrine psychosis, which resembles both schizophrenia and amphetamine psychosis, is well-documented after higher doses of the drug (Herridge and a'Brook, 1968;Roxanas and Spalding, 1977).…”