Table 4.
Assessment of methodological issues in studies investigating the effect of St John’s wort (SJW) on CYP3A activity
| Trial | Design | Analysis of SJW extract performed | CYP3A potential inducers and inhibitors controlled for | Assessment of SJW compliance |
|---|---|---|---|---|
| Jarson LI160 standardized 0.03% hypericins | ||||
| Bauer 2002 [23] | BA | No | Not stated | No |
| Bauer 2003 [24] | BA | No | During study grapefruit juice | No |
| Dresser 2003 [25] | BA | No | 1 week prior to study ‘herbal and citrus products’, 3 days prior other medications | No |
| Dürr 2000 [26] | BA | No | 5 days prior citrus fruits | No |
| Frye 2004 [27] | BA | No | 48 h prior to pharmacokinetic testing grapefruit | Yes |
| Herbert 2004 [28] | BA | Yes | During study grapefruit | Yes |
| Johne 2002 [29] | BA | No | Prior to study urine/blood screen for cannabinoids, amphetamines, morphines, benzodiazepines, barbituates and cocaine | Yes |
| Mai 2003 [30] | BA | No | During study grapefruit | Yes |
| Mai 2004 [12] | R, CO | Yes | During study, grapefruit | No |
| Markowitz 2003 [31] | BA | Yes | During study grapefruit | No |
| Pfrunder 2003 [32] | R, CO | No | During study grapefruit | Yes |
| Wenk 2004 [33] | BA | No | During study grapefruit | No |
| St JohnSelect Indena S.p.A extract standardized to 0.3% hypericin and ≥4% hyperforin | ||||
| Smith 2004 [34] | BA | No | Not stated | No |
| Wang 2004 [35] | R, PC, CO | No | One month prior to study SJW, herbal medicines, OTC medicines | No |
| Unknown SJW extract A, standardized to 0.3% hypericin | ||||
| Gurley 2002 [36] | R, BA | Yes | 5 days prior to study probe drug administration and during study, grapefruit | No |
| Unknown SJW extract B, standardized to 0.3% hypericin | ||||
| Hall 2003 [37] | BA | Yes | 4 weeks prior to study SJW, 2 weeks prior grapefruit | Yes |
| Wang 2001 [22] | BA | Yes | 3 months prior to study marijuana, 4 weeks prior SJW, 2 weeks prior pharmaceutical drugs, grapefruit | No |
| Unknown SJW extract C, standardized hypericin and hyperforin content | ||||
| Jiang 2004 [38] | R, CO | Yes | 2 weeks prior to study all medications | No |
| Unknown SJW extract D, standardized to 3–6% hyperforin | ||||
| Tannergren 2004 [39] | BA | No | 3 days prior to pharmacokinetic testing grapefruit | No |
| Esbericum® | ||||
| Arold 2005 [14] | DB, R, PC, P | No | During study < 4 cups/day quinine containing beverages On pharmacokinetic test days (24 h before and after probe drug) grapefruit, quinine | Yes |
| Remotiv Ze 117 | ||||
| Brattstöm [40] | BA | No | Not stated | Yes |
| Modified low-hyperforin LI160 | ||||
| Mai 2004 [12] (also listed above) | R, CO | Yes | During study, grapefruit | No |
| Early Indina S.p.A extract standardized to 0.3% hypericin | ||||
| Burstein 2000 [41] | BA | Yes | 30 days prior to study SJW | Yes |
| Piscitelli 2000 [42] | BA | Yes | 30 days prior to study SJW | No |
| Roby 2000 [43] | BA | Yes | During study grapefruit, herbal dietary supplements and herbal tea | No |
| Unknown SJW extract E, standardized to 0.3% hypericin | ||||
| Gurley 2005 [21] | R, BA | Yes | During the study fruit juices, food medicine diary to document compliance | Yes |
| Unknown SJW extract F, standardized 0.3% hypericin | ||||
| Kawaguchi 2004 [44] | R, DB, PC, CO | No | During the study grapefruit, herbal and dietary supplements, and herbal tea | Yes |
| Sugimoto 2001 [45] | DB, CO | No | During the study grapefruit, herbal and dietary supplements, and herbal tea | No |
| Morimoto 2004 [46] | R, CO | Yes | 2 weeks prior to study and during the study grapefruit and SJW | No |
| Unknown SJW extract G, standardized to 0.3% hypericin | ||||
| Markowitz 2000 [47] | BA | No | Not stated | No |
| Unknown SJW extract H | ||||
| Mathijssen 2002 [48] | R, CO? | No | Not stated | No |
| Unknown SJW extract I | ||||
| Xie 2005 [49] | BA | No | 30 days prior to study ‘known enzyme-altering drugs or herbal products’ | No |
BA, Before-and-after; CO, crossover; R, randomized; DB, double-blind; P, placebo-controlled.