The effect of St John's wort extracts on CYP3A: a systematic review of prospective clinical trials.

AIM: The aim of this systematic review was to assess the quality and outcomes of clinical trials investigating the effect of St John's wort extracts on the metabolism of drugs by CYP3A. METHODS: Prospective clinical trials assessing the effect of St John's wort (SJW) extracts on metabolism by CYP3A were identified through computer-based searches (from their inception to May 2005) of Medline, Cinahl, PsycINFO, AMED, Current Contents and Embase, hand-searches of bibliographies of relevant papers and consultation with manufacturers and researchers in the field. Two reviewers selected trials for inclusion, independently extracted data and recorded details on study design. RESULTS: Thirty-one studies met the eligibility criteria. More than two-thirds of the studies employed a before-and-after design, less than one-third of the studies used a crossover design, and only three studies were double-blind and placebo controlled. In 12 studies the SJW extract had been assayed, and 14 studies stated the specific SJW extract used. Results from 26 studies, including all of the 19 studies that used high-dose hyperforin extracts (>10 mg day(-1)), had outcomes consistent with CYP3A induction. The three studies using low-dose hyperforin extracts (<4 mg day(-1)) demonstrated no significant effect on CYP3A. CONCLUSION: There is reasonable evidence to suggest that high-dose hyperforin SJW extracts induce CYP3A. More studies are required to determine whether decreased CYP3A induction occurs after low-dose hyperforin extracts. Future studies should adopt study designs with a control phase or control group, identify the specific SJW extract employed and provide quantitative analyses of key constituents.

Programs and pregnancy: a survey of policies.

If a woman becomes pregnant while on flight status, a potential conflict exists between the needs and desires of the program and those of the flight crew member. Association of Air Medical Services (AAMS) member programs were surveyed to determine the extent of pregnancy policy standards within the air medical profession. A survey was mailed to 150 AAMS program directors in the fall of 1988. The survey was followed with a second mailing and a telephone follow-up for clarification. Replies were received from 110 program directors. Fifty-five percent of those responding noted they had a policy on flight crew member (FCM) pregnancy. Thirty percent noted a date prior to term that the pregnant FCM (PFCM) would be removed from flight status. Seventy percent of the programs noted that they had not previously had a PFCM. Over half of the programs allowed PFCMs to fly until the third trimester, with just under a quarter allowing flights until 38 weeks or greater. There are few articles specifically referring to air medical FCM pregnancy, and policies regarding FCM pregnancy differ widely among the AAMS member programs.