Ritonavir Garlic

Garlic bulb Ritonavir Two brief case reports describe gastrointestinal toxic effects in patients taking garlic and ritonavir. 

Gallicano K, Choudhri S, Leclaire T, Poster BC. Effect of short-term administration of garlic supplements on single-dose ritonavir pharmacokinetics in healthy volunteers. Br J Clin Pharmacol 2003 55 199-202. 

Because of reported antiplatelet effects, patients using anticlotting medications (eg, warfarin, aspirin, ibuprofen) should use garlic cautiously. Additional monitoring of blood pressure and signs and symptoms of bleeding is warranted. Garlic may reduce the bioavailability of saquinavir, an antiviral protease inhibitor, but it does not appear to affect the bioavailability of ritonavir. 

Clinically important, potentially hazardous interactions with bepridil, cisapride, dasatinib, dofetilide, ergot derivatives, etravirine, fentanyl, fesoterodine, garlic, indinavir, irinotecan, ixabepilone, lapatinib, lovastatin, marihuana, midazolam, pimozide, proton-pump inhibitors, raltegravir, rifampin, ritonavir, sildenafil, simvastatin, solifenacin, St John s wort, temsirolimus, triazolam... 

A garlic supplement reduced the plasma levels of saquinavir by 50% in one study, but had little effect in another. Another garlic supplement did not significantly affect the pharmacokinetics of a single dose of ritonavir. 

Although information is limited, a reduction in saquinavir plasma levels of the magnitude seen in the first study could diminish its antiviral efficacy. All garlic supplements should probably be avoided in those taking saquinavir as the sole protease inhibitor (no longer generally recommended). While the pharmacokinetic effect on single-dose ritonavir was not clinically important, this requires confirmation in a multiple-dose study. 

Laroche M, Choudhri S, Gallicano K, Foster B. Severe gastrointestinal toxicity widi concomitant ingestion of ritonavir and garlic. Can J Infect Dis (1998) 9 (Siqipl A), 76A. 

No effects on ritonavir (400 mg, single dose) were observed after ingestion of 10 mg garlic extract (equivalent to 1 g of fresh garlic) daily for four days (Gallicano et al. 2003). 

Two cases of gastrointestinal toxicity were reported in patients taking garlic and the protease inhibitor, ritonavir (Laroche et al. 1999). 

Laroche, M., S. Choudhri, K. Gallicano, and B. Foster. 1999. Severe gastrointestinal toxicity with concomitant ingestion of ritonavir and garlic [Abstract only]. Can.. Infect. Dis. 9(Suppl A) 471P. 

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