Effects of Garlic Supplements on Opioids in Healthy Volunteers

Phase 4

Completed

Conditions: Healthy, No Evidence of Disease

Interventions: Dietary Supplement: garlic powder tablets
Drug: oxycodone

Registration Number: NCT00499460

Lead Sponsor: Fred Hutchinson Cancer Center

Brief Summary: RATIONALE: Garlic supplements may alter the pharmacokinetics of oxycodone, thereby affecting its effectiveness as an opioid analgesic for the relief of moderate or severe pain.

PURPOSE: This randomized phase 4 trial is studying how garlic supplements may change the pharmacokinetics of oxycodone and its analgesic and side effects in healthy volunteers.

Detailed Description: OBJECTIVES:

* To determine whether CYP3A (Cytochrome P450 3A) and/or P-glycoprotein mediated interactions exist between garlic supplements and oxycodone (a commonly used oral opioid analgesic) in healthy volunteers.

OUTLINE:

This is a single-blind, randomized, crossover study. Participants are randomized to 1 of 2 arms. Each arm entails two 30-day treatment periods, with a washout of at least 4 weeks in between.

* Arm I: In Period 1, participants receive oral garlic powder twice daily on days 1-28 and oral oxycodone on day 28. In Period 2, participants receive oral placebo twice daily on days 1-28 and oral oxycodone on day 28.

* Arm II: In Period 1, participants receive oral placebo twice daily on days 1-28 and oral oxycodone on days 28. In Period 2, participants receive oral garlic powder twice daily on days 1-28 and oral oxycodone on day 28.

In both periods of each arm, participants receive a combination of oral midazolam and oral digoxin for CYP3A and P-glycoprotein phenotyping on day 29. Blood samples are collected periodically and analyzed by liquid chromatography-mass spectrometry (LC-MS).

Blood and urine samples are collected after receiving oxycodone for pharmacokinetic characterization. Plasma concentrations of oxycodone and its metabolites are measured by LC-MS.

Response to experimentally induced pain by the Cold Pressor Test (CPT) is assessed at baseline and periodically after oxycodone treatment. Subjective ratings of opioid side effects are assessed by validated questionnaires for somatic side effects and cognitive function impairments.

Recruitment & Eligibility

Status: COMPLETED

Sex: All

Target Recruitment: 15

Inclusion Criteria

Not provided

Exclusion Criteria

Not provided

Study & Design

Study Type: INTERVENTIONAL

Study Design: CROSSOVER

Arm && Interventions

Group	Intervention	Description
Arm II	garlic powder tablets	Two 30-day treatment periods separated by a washout of at least 4 weeks. In Period 1, participants receive oral placebo twice daily on days 1-30, oral oxycodone on day 28, and a combination of oral midazolam and digoxin on day 29. In Period 2, participants receive oral garlic powder tablet twice daily on days 1-30, oral oxycodone on day 28, and a combination of oral midazolam and digoxin on day 29.
Arm I	garlic powder tablets	Two 30-day treatment periods separated by a washout of at least 4 weeks. In Period 1, participants receive oral garlic powder tablet twice daily on days 1-30, oral oxycodone on day 28, and a combination of oral midazolam and digoxin on day 29. In Period 2, participants receive oral placebo twice daily on days 1-30, oral oxycodone on day 28, and a combination of oral midazolam and digoxin on day 29.
Arm I	oxycodone	Two 30-day treatment periods separated by a washout of at least 4 weeks. In Period 1, participants receive oral garlic powder tablet twice daily on days 1-30, oral oxycodone on day 28, and a combination of oral midazolam and digoxin on day 29. In Period 2, participants receive oral placebo twice daily on days 1-30, oral oxycodone on day 28, and a combination of oral midazolam and digoxin on day 29.
Arm II	oxycodone	Two 30-day treatment periods separated by a washout of at least 4 weeks. In Period 1, participants receive oral placebo twice daily on days 1-30, oral oxycodone on day 28, and a combination of oral midazolam and digoxin on day 29. In Period 2, participants receive oral garlic powder tablet twice daily on days 1-30, oral oxycodone on day 28, and a combination of oral midazolam and digoxin on day 29.

Primary Outcome Measures

Name	Time	Method
Oxycodone Oral Clearance	Serial blood sampling over 24 hours after a 15-mg oral dose of oxycodone	Oxycodone oral clearance is computed by Dose/AUC, where AUC is the area under the plasma oxycodone concentration-time curve from time zero to infinity. Oral clearance is a measure of the rate at which oxycodone is cleared from the body via metabolism.

Secondary Outcome Measures

Name	Time	Method
Cold Pressor Tolerance AUC	Repeated testing for tolerance to Cold Pressor Test just before and at 45, 90, 150 and 300 min after a single 15-mg oral dose of oxycodone	Cold Pressor Test measures response to experimentally induced pain, in this case by immersion of a subject's hand in icy-cold water. Tolerance is the duration of time a subject is able to keep his/her hand immersed in the cold water. A prolongation in tolerance time indicates analgesic response to oxycodone treatment. Cold Pressor Tolerance AUC is the area under the tolerance versus time curve over a 300-min period after a test dose of oxycodone. Because of non-normality in sample distribution, log transformed AUC estimates were analyzed by Generalized Linear Model.
Somatic Side Effects Total Score	SSE scores at 150 min after a single 15-mg oral dose of oxycodone	Subjects rated the bodily side effects they experienced at 90, 150 and 300 min after oxycodone administration on a 35-item Somatic Side Effects (SSE) questionnaire. Total score (i.e., average of the scores for all 35 items) ranges on a numerical scale from 0 (no somatic side effects) to a maximum of 4 (extreme somatic aide effects). Only the peak SSE scores at 150 min are reported herein.
Cognitive-Affective Side Effects Total Score	CASE scores at 150 min after a single 15-mg oral dose of oxycodone	Subjects rated the mental side effects they experienced at 90, 150 and 300 min after oxycodone administration on a 36-item Cognitive-Affective Side Effects (CASE) questionnaire. Total score (i.e., average of the scores for all 36 items) ranges on a numerical scale from 0 (no somatic side effects) to a maximum of 4 (extreme somatic aide effects). Only the peak CASE scores at 150 min are reported herein.
Oral Midazolam Test	Serial blood sampling over 6 hours after a 5-mg oral test dose of midazolam	Midazolam when given orally is a probe substrate for the in vivo intestinal and hepatic activity of CYP3A (Cytochrome P450 3A) enzymes. The phenotype index in this case is the area under the plasma midazolam concentration from time zero to 360 min after a 5-mg oral test dose. A decrease in oral midazolam AUC indicates enhanced activity of CYP3A enzymes, possibly as a result of enzyme induction.
Oral Digoxin Test	Serial blood sampling over 4 hours after a 0.5-mg oral test dose of digoxin	Digoxin when given orally is a probe substrate for the efflux activity of P-glycoprotein in the small intestine. The phenotype index in this case is the area under the plasma digoxin concentration from time zero to 240 min after a 0.5-mg oral test dose. A decrease in oral digoxin AUC indicates an enhanced activity of P-glycoprotein, possibly as a result of transporter upregulation.