Pretreatment with grapefruit juice is associated with increased bioavailability and changes in the pharmacodynamics of midazolam that may be clinically important, particularly in patients with other causes for increased midazolam bioavailability such as advanced age, cirrhosis of the liver, and administration of other inhibitors of cytochrome P450.

AIMSThe objective of this review was to collect available data on the following: (i) adverse effects observed in humans from the intake of plant food supplements or botanical preparations; (ii) the misidentification of poisonous plants; and (iii) interactions between plant food supplements/botanicals and conventional drugs or nutrients. METHODSPubMed/MEDLINE and Embase were searched from database inception to June 2014, using the terms 'adverse effect/s', 'poisoning/s', 'plant food supplement/s', 'misidentification/s' and 'interaction/s' in combination with the relevant plant name. All papers were critically evaluated according to the World Health Organization Guidelines for causality assessment. RESULTSData were obtained for 66 plants that are common ingredients of plant food supplements; of the 492 papers selected, 402 (81.7%) dealt with adverse effects directly associated with the botanical and 89 (18.1%) concerned interactions with conventional drugs. Only one case was associated with misidentification. Adverse effects were reported for 39 of the 66 botanical substances searched. Of the total references, 86.6% were associated with 14 plants, including Glycine max/soybean (19.3%), Glycyrrhiza glabra/liquorice (12.2%), Camellia sinensis/green tea ( 8.7%) and Ginkgo biloba/gingko (8.5%). CONCLUSIONSConsidering the length of time examined and the number of plants included in the review, it is remarkable that: (i) the adverse effects due to botanical ingredients were relatively infrequent, if assessed for causality; and (ii) the number of severe clinical reactions was very limited, but some fatal cases have been described. Data presented in this review were assessed for quality in order to make the results maximally useful for clinicians in identifying or excluding deleterious effects of botanicals.

Aims Saquinavir is a potent HIV protease inhibitor whose effectiveness is limited in vivo by its low bioavailability. Since saquinavir is metabolized by CYP3A4, the effect of grapefruit juice, an inhibitor of CYP3A4, was investigated on its bioavailability. Methods After an overnight fast, eight healthy volunteers were treated with either 400 ml grapefruit juice or water before intravenous (12 mg) or oral saquinavir (600 mg) was administered. Serial blood samples were obtained over the following 24 h and standardized meals were served 5 and 10 h after the administration of saquinavir. The plasma concentrations of saquinavir were determined by highperformance liquid chromatography and pharmacokinetic parameters were calculated by routine methods. Results The AUC was not affected by grapefruit juice after intravenous administration, but it increased significantly from 76±96 (water, mean (s.d.) to 114±70 (mg l −1 h (grapefruit juice) after oral saquinavir. Similarly, the oral bioavailability of saquinavir increased by a factor of 2 with grapefruit juice (from 0.7% to 1.4%). In contrast, clearance, volume of distribution and elimination half-life of saquinavir were not affected by grapefruit juice. After oral, but not after intravenous administration, the plasma concentration-time curve showed a second peak after lunch irrespective of pretreatment, suggesting enhancement of absorption by food. Conclusions The studies demonstrate that grapefruit juice increases the bioavailability of saquinavir without affecting its clearance, suggesting that inhibition of intestinal CYP3A4 may contribute. Since the antiretroviral effect of saquinavir is dosedependent, inhibition of CYP3A4 may represent a way to enhance its effectiveness without increasing the dose.

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