Kava Kava: No Impact on Key Liver Enzyme

observational-study PMID: 17495878

Kava Kava: No Impact on Key Liver Enzyme

Quick Summary: A 2008 study tested if kava kava affects how the body processes certain drugs by looking at a liver enzyme called CYP3A. Researchers found that kava kava did not change this enzyme's activity in healthy people. In comparison, goldenseal strongly slowed it down, which could lead to drug interactions.

What the Research Found

This study checked how two herbs—kava kava and goldenseal—affect CYP3A, a liver enzyme that breaks down many medications like pain relievers, cholesterol drugs, and antibiotics. CYP3A helps your body clear these drugs safely. If an herb blocks it, drugs can build up and cause side effects.

Kava kava showed no effect: It didn't change how the test drug (midazolam) was processed in the body. Levels stayed the same, meaning no interference with CYP3A.
Goldenseal did block CYP3A: It raised drug levels by about 63%, slowed clearance by around 36%, and extended the drug's half-life by 57%. This suggests goldenseal could mix badly with many common meds.

The main takeaway? Kava kava is less likely to cause problems with drugs that rely on CYP3A, unlike goldenseal.

Study Details

Who was studied: 16 healthy adults who volunteered for the trial. The study didn't share details like age, gender, or background, so results may not apply to everyone.
How long: Each herb was taken for 14 days straight. There was a 30-day break (washout) before switching to the other herb, making the full study last about two months per person.
What they took: Participants took kava kava capsules (300 mg, three times a day, standardized to 30% kavalactones) or goldenseal capsules (450 mg, three times a day, standardized to 8% hydrastine). Before and after each herb phase, they took an 8 mg dose of midazolam (a safe test drug) to measure CYP3A activity through blood tests and drug processing analysis.

What This Means For You

If you use kava kava for relaxation, anxiety, or sleep—like many people do— this study eases worries about it messing with your prescription meds. At the doses tested (about 900 mg daily), kava didn't alter how your liver handles CYP3A-dependent drugs, such as statins for cholesterol or some blood pressure pills.

Good news for kava users: Lower risk of interactions compared to goldenseal. You might combine it with common meds without big issues, but always check with your doctor.
Watch out for goldenseal: If you're taking it for colds or digestion, it could make drugs like opioids or heart meds stronger and riskier—talk to a pharmacist.
Real-life tip: Everyone's body is different. If you have liver issues or take multiple meds, consult a healthcare pro before starting any herb. This study used short-term, moderate doses, so long-term use needs more research.

Study Limitations

No research is perfect, and this one has some gaps to keep in mind:
- Small group: Only 16 people, so findings might not hold for larger or more diverse crowds, like older adults or those with health conditions.
- No fake pill (placebo): Without a control group taking a dummy supplement, it's harder to rule out other influences like diet or expectations.
- Short time frame: Just 14 days of use—longer kava habits (common for stress relief) weren't tested, and effects could differ.
- Missing details: No info on participants' ages, sexes, or ethnicities, which can affect how herbs work.
- One dose level: Results apply to 300 mg three times daily; higher amounts might behave differently.

Overall, this adds reassuring evidence for kava's safety with certain drugs, but more studies would help confirm it for everyday use. Always prioritize talking to your doctor for personalized advice.

Key Findings

This 2008 study found that kava kava supplementation (300 mg three times daily) did not significantly alter the pharmacokinetics of midazolam (MDZ), a probe drug for CYP3A activity, in healthy volunteers. In contrast, goldenseal (450 mg three times daily) significantly inhibited CYP3A, increasing MDZ area under the curve (AUC) by ~63% and half-life (T_1/2) by 57%. The results indicate no clinically relevant herb-drug interactions between kava kava and CYP3A substrates, unlike goldenseal.

Study Design

Type: Observational crossover study (non-randomized, two-phase).
Methodology: Sixteen healthy adults received either goldenseal or kava kava for 14 days, followed by a 30-day washout period before crossing over to the other supplement. MDZ (8 mg oral) was administered pre- and post-supplementation to assess CYP3A activity via pharmacokinetic analysis.
Sample Size: 16 participants (demographics unspecified).
Duration: 14-day supplementation phases with 30-day washout between groups.

Dosage & Administration

Kava Kava: 300 mg capsules three times daily (standardized to 30% kavalactones).
Goldenseal: 450 mg capsules three times daily (standardized to 8% hydrastine).
MDZ Administration: 8 mg oral dose pre- and post-supplementation.
Supplement Duration: 14 consecutive days per herb, separated by 30-day washout.

Results & Efficacy

Goldenseal:
AUC_0-∞: Increased from 107.9±43.3 to 175.3±74.8 ng·h/ml (p < 0.05).
Clearance (Cl/F/kg): Decreased from 1.26±0.59 to 0.81±0.45 L/h/kg (p < 0.05).
T_1/2: Extended from 2.01±0.42 to 3.15±1.12 hours (p < 0.05).
C_max: Rose from 50.6±26.9 to 71.2±50.5 ng/ml (p < 0.05).
Kava Kava: No statistically significant changes in MDZ pharmacokinetics (data unspecified).

Limitations

Small Sample Size: Only 16 participants, limiting generalizability.
Lack of Placebo Control: No placebo group, increasing risk of bias.
Short Duration: 14-day supplementation may be insufficient to detect long-term effects.
Demographic Gaps: No details on age, sex, or ethnicity provided.
Single Dose of Kava: Findings may not apply to higher doses or prolonged use.

Clinical Relevance

For supplement users, this study suggests kava kava (300 mg thrice daily) does not interfere with CYP3A-mediated drug metabolism, reducing concerns about interactions with medications like MDZ, statins, or immunosuppressants. However, goldenseal showed strong CYP3A inhibition, warranting caution with concurrent drugs. Limitations include the lack of placebo control and small sample, so results should be interpreted cautiously. Users should still consult healthcare providers when combining herbs with medications, as individual variability and longer-term effects remain unstudied.

This analysis focuses solely on the provided study; further research is needed to validate these findings in larger, more diverse populations.