[Grapefruit juice: potential drug interaction]. / II succo di pompelmo: una potenziale interazione con i farmaci.

More than a decade has passed since it was unintentionally discovered that grapefruit juice interacts with certain drugs. The coadministration of these drugs with grapefruit juice can markedly elevate drug bioavailability, and can alter pharmacokinetic and pharmacodynamic parameters of the drug. The predominant mechanism for this interaction is the inhibition of cytochrome P-450 3A4 in the small intestine, resulting in a significant reduction of drug presystemic metabolism. An additional mechanism is the inhibition of P-glycoprotein, a transporter that carries drug from the enterocyte back to the gut lumen, resulting in a further increase in the fraction of drug absorbed. Some calcium channel antagonists, benzodiazepines, HMG-CoA reductase inhibitors and cyclosporine are the most affected drugs. A single exposure to one glass of the grapefruit juice can usually produce the maximal magnitude of the interaction. The data available so far, concerning this interaction and its clinical implications, are reviewed in this article. It is likely that more information regarding this interaction will accumulate in the future, and awareness of such is necessary for achieving optimal drug therapy.

Effects of maternal exposure to polychlorobiphenyls (PCBs) on F1 generation behavior in the rat.

The effect of Fenclor 42 (PCB) exposure of female rats (Fischer 344 strain) was studied through assessment of the behavioral development of their F1 progeny. Female rats were exposed to PCB according to the following treatment schedule: (A) (5 days) 2 weeks prior to mating, (B) during gestation (Days 6-15 of pregnancy), (C) during lactation (Days 1-21 after delivery). Behavioral endpoints of motor reflexes, motor coordination, activity (preweaning behaviors), and learning (postweaning behavior) were evaluated for PCB ip dosages of 5-10 mg/kg/day for 5 days (preconception exposure), and PCB oral dosages of 2-4 mg/kg/day for 10 days (in utero exposure) and of 1-2 mg/kg/day for 20 days (during lactation exposure). Dosage-dependent differences in the evaluated behaviors were found in the offspring of the PCB-exposed females when compared to the offspring of corn-oil (vehicle)-exposed females. Significant differences in the development of cliff avoidance reflexive behavior, swimming ability, and open field activity were particularly evident. Furthermore the PCB exposure of female rats during gestation and lactation resulted in impaired acquisition of the active avoidance behavior while preconceptional PCB exposure significantly affected active avoidance performance as reflected in increased number of avoidance responses to reach criterion for extinction. These results show that Fenclor 42 does possess a significant risk to the offspring of exposed females, and further illustrate the sensitivity of progeny behavioral assessment in detecting suspected functional teratogenesis.