Paroxetines Effect on Tramadols Metabolism and Pharmakodynamics: a Dose Response Study

• Status: Unknown status
• Trial end date: 2009-02-01
• Target enrollment: 0
• Participant gender: All

Summary

The purpose of the study is to examine the connection between the dose of paroxetine and the effect of paroxetine on tramadols metabolism and thereby the effect of tramadol on the median pupil size.

In the study 12 healthy volunteers are going through 5 phases where they are suppose to consume a determined dose of tramadol and 5 various doses of paroxetine corresponding to the 5 phases. Fig 1.

phases 1 2 3 4 5 Dosis Tramadol mg 50 50 50 50 50 Dosis Paroxetine mg Placebo 10 20 30 50 Paroxetin / placebo 2 ½ placebo 2 placebo 1 ½ placebo 1 placebo tablets ½ paroxetine 1 paroxetine 1 ½ paroxetine 2 ½ paroxetine Fig. 1 summary of the 5 phases

There is a variation in the time where maximal plasma concentration is obtained in consumption of respectively tramadol (1 - 2 hours) and paroxetine (6 hours). For that reason there has to be at least 6 hours between the administration of paroxetine and tramadol.

The healthy volunteer brings the research medicine home and consumes it before bedtime the night before the day of the study. At eight o'clock next morning the healthy volunteer arrives to the first pupil measurement and consumption of tramadol. Tree hours later the next pupil measurement is carried through. The healthy volunteer accumulates his or her urine until 2 pm. As paroxetine is a irreversible inhibitor of the enzyme CYP2D6 there has to go at least 14 days before the next phase takes place. In that amount of time there can be recreated a new pool of enzyme.

• Phase: Phase 4
• Accepts Healthy Volunteers?: Accepts Healthy Volunteers

Details

• Lead Sponsor: University of Southern Denmark
• Treatments: Paroxetine; Tramadol

Criteria

Inclusion Criteria:

• Healthy volunteers judged from the medical anamnesis and examination, inclusive a laboratory examination.

• Signed written approval and authorization, witch give relevant people (the GCP-unit, the the Danish Medicines Agency and the ethics committee of Southern Denmark) access to documents and data of interest to this study

• Age: 18 - 45 years

• Women must use one of the Danish Medicines Agency defined safe contraception. A negative pregnancy test has to ensure that the volunteers are not pregnant at the start of the study

• All the volunteers have to be phenotyped as CYP2D6 extensive metabolizer (EM) by a "tramadol test": the volunteer ingest 50 mg tramadol and all urine is collected fore 8 hours. By a HPLC method the metabolic ratio (MR) of (-)-M1/(+)-M1 is determined in the urine. Volunteers with a MR-ratio smaller than 2 is defined as CYP2D6 EM's

Exclusion Criteria:

• Any clinical significant observation at the medical- or laboratory examination

• Daily use of medicine or alcohol. Periodic use of medicine can be accepted after individual valuation by a doctor

• Allergy or intolerance to paroxetine or tramadol

• Former participation in a clinical study in the last 3 months