Effects of Garlic Supplements on Opioids in Healthy Volunteers

Fred Hutchinson Cancer Center (FHCC)

Status and phase: Completed; Phase 4

Conditions: Healthy, No Evidence of Disease

Treatments: Dietary Supplement: garlic powder tablets; Drug: oxycodone

Study type: Interventional

Funder types: Other; NIH

Identifiers

NCT00499460

2040.00

CDR0000551927 (Other Identifier)

R21CA118334 (U.S. NIH Grant/Contract)

IR-6130 (Other Identifier)

Details and patient eligibility

About

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.

Full 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.

Enrollment: 15 patients

Sex: All

Ages: 21 to 45 years old

Volunteers: Accepts Healthy Volunteers

Inclusion criteria

• Healthy volunteer
• Body mass index 20-32

Exclusion criteria

• Not pregnant
• No history of cardiopulmonary, liver, renal, endocrine, neurologic, or psychiatric disease
• No anemia
• No known adverse reactions to opioids, benzodiazepines, cardiac glycosides, or garlic supplements
• No known allergy or hypersensitivity to sulfur-containing food or drugs
• No significant gastrointestinal intolerance to lactose in dairy products
• No recent history of alcohol or substance abuse
• No history of or concurrent heavy daily consumption of allium vegetables (i.e., garlic, shallots, leeks, and chives)
• No handicaps due to visual and hearing impairments
• No resting heart rate < 50 beats per minutes
• No abnormal cardiac rhythm by EKG
• No unusually sensitive response or resistance to pain stimulation (Cold Pressor Test)
• Must be right handed
• No color blindness
• No history of learning disabilities or dyslexia
• Must be literate and proficient in English
• Must be a nonsmoker
• No concurrent medication except oral contraceptives
• No concurrent grapefruit or grapefruit juice
• No other concurrent over-the-counter herbal products or herbal tea

Trial design

Primary purpose: Basic Science

Allocation: Randomized

Interventional model: Crossover Assignment

Masking: Single Blind

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15 participants in 2 patient groups

Arm I

Other group

Description:

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.

Treatment:

Drug: oxycodone

Dietary Supplement: garlic powder tablets

Arm II

Other group

Description:

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.

Treatment:

Drug: oxycodone

Dietary Supplement: garlic powder tablets