Herb–Drug Interactions: Worlds Intersect with the Patient at the Center

Abstract

This review examines three bodies of literature related to herb–drug interactions: case reports, clinical studies, evaluations found in six drug interaction checking resources. The aim of the study is to examine the congruity of resources and to assess the degree to which case reports signal for further study. A qualitative review of case reports seeks to determine needs and perspectives of case report authors. Methods: Systematic search of Medline identified clinical studies and case reports of interacting herb–drug combinations. Interacting herb–drug pairs were searched in six drug interaction resources. Case reports were analyzed qualitatively for completeness and to identify underlying themes. Results: Ninety-nine case-report documents detailed 107 cases. Sixty-five clinical studies evaluated 93 mechanisms of interaction relevant to herbs reported in case studies, involving 30 different herbal products; 52.7% of these investigations offered evidence supporting reported reactions. Cohen’s kappa found no agreement between any interaction checker and case report corpus. Case reports often lacked full information. Need for further information, attitudes about herbs and herb use, and strategies to reduce risk from interaction were three primary themes in the case report corpus. Conclusions: Reliable herb–drug information is needed, including open and respectful discussion with patients.

Herbal supplements in Jordan: a cross-sectional survey of pharmacists’ perspectives and knowledge

“…11 The health consequences of these interactions were widely reported in both case reports and clinical studies. [12][13][14][15][16][17][18][19][20] Patients taking anticancer, cardiovascular and immunosuppressant medications were predominantly affected by these interactions. 21 With the lack of awareness in identifying and reporting these reactions among the public and healthcare professionals, this risk could be amplified.…”

“…Moreover, due to the common use of these products in patients with comorbidities, interactions with prescription and OTC medications are possible, leading to a decrease in the effectiveness of pharmacological treatments or toxic manifestations 11. The health consequences of these interactions were widely reported in both case reports and clinical studies 12–20. Patients taking anticancer, cardiovascular and immunosuppressant medications were predominantly affected by these interactions 21.…”

Potential pharmacokinetic and pharmacodynamic herb-drug interactions of Andrographis paniculata (Burm. f.) and andrographolide: A systematic review

“…The most common mechanism underlying pharmacokinetic interactions is the drug-mediated inhibition and induction of drugmetabolizing CYP isozymes (4,38). Therefore, in vitro studies on the inhibition or induction of the expression and activity of the CYP family of enzymes can be conducted to assess potential drug interactions (1,3,38).…”

“…Strategies that deal with HDIs cases in clinical practice are often inappropriate because the sources of information related to HDIs that can be used as a guide in therapy are limited. The type and composition of herbal medicines commonly used by patients are also poorly described (3). The most widely reported cases of the emergence of HDIs today are the modulation of herbal medicinal components in the drug metabolism system involving cytochrome P450 (CYP)-metabolizing enzymes (4).…”

“…Chemical compounds in herbal medicines can act as reversible inhibitors, irreversible inhibitors, or inductors of the CYP enzyme; they alter the pharmacokinetic profiles of drugs and cause an increase or decrease in drug levels in plasma, tissues, and urine (5). Previous reviews found that HDIs in the pharmacokinetic phase are the most prevalent, accounting for more than 90% of the total cases, including supported and unsupported case reports (3). HDI-induced changes in a drug's pharmacokinetic profile can affect drug levels in the blood and the amount of drug binding to a target action/receptor, which can increase or decrease the effectiveness of its therapy because of the emergence of HDI mechanisms in the pharmacodynamic phase in the form of additive, synergistic, or antagonistic effects on pharmacological activity (6).…”