EVALUATING HERBAL-DRUG INTERACTIONS
Clinical decision support tools and databases are available to help OHCPs stratify herbal-drug interactions according to the level of risk they pose to patients. Two databases employed to evaluate interactions – Lexicomp (Hudson, OH) and the Natural Medicines Comprehensive Database (Stockton, CA) – were selected for the purposes of this course to determine the risks associated with CAM supplementation and particular drugs prescribed most commonly by dentists (Lexicomp, n.d.; Natural Medicines Comprehensive Database, n.d.a).
Lexicomp assigns grades to interactions as shown in Table 3. The Natural Medicines Comprehensive Database rates herbal-drug interactions with a traffic-light grading system (Table 4). Red-light interactions should be avoided, as these supplement-medication combinations are contraindicated and serious adverse outcomes could occur. Yellow-light interactions indicate caution and perhaps avoidance of the combination unless the benefits outweigh the risks. Green-light interactions indicate minimal risk of combination therapy. Both of these databases report interactions according to likelihood of occurrence, severity, and level of evidence, which aids in validating concurrence of data (Table 5). Regardless, patients should always be advised to be aware of warning signs of a potential interaction, however insignificant the reaction may seem.
Table 3: Lexicomp’s Risk Rating Definitions for Drug Interactions Risk Rating Action Description A No known interaction.
Data have not demonstrated either pharmacodynamic or pharmacokinetic interactions between the specified agents. Data demonstrate that the specified agents may interact with one another, but there is little to no evidence of clinical concern related to their concomitant use. Data demonstrate that the specified agents may interact with one another in a clinically significant manner. The benefits of concomitant use of these two medications usually outweigh the risks. An appropriate monitoring plan should be implemented to identify potential negative effects. Dosage adjustments of one or both agents may be needed in a minority of patients. Data demonstrate that the two medications may interact with one another in a clinically significant manner. A patient-specific assessment must be conducted to determine whether the benefits of concomitant therapy outweigh the risks. Specific actions must be taken to realize the benefits and/ or minimize the toxicity resulting from concomitant use of the agents. These actions may include aggressive monitoring, empiric dosage changes, and choice of alternative agents.
No action needed.
B
Monitor therapy.
C
Consider therapy modification.
D
X Data demonstrate that the specified agents may interact with each other in a clinically significant manner. The risks associated with concomitant use of these agents usually outweigh the benefits. Use of these agents in combination are generally contraindicated. Note. Adapted from “Lexicomp Online for Dentistry,” by Wolters Kluwer, n.d., Retrieved from http://webstore.lexi.com/ONLINE-Software-for-Dentists Table 4: The Natural Medicines Comprehensive Database Level of Interaction Significance for Herbal-Drug Interactions Likely Probable Possible Unlikely High Moderate Mild Insignificant Red = Major risk; do not use the combination; contraindicated; strongly discourage patients from using this Avoid combination. Table 5: Additional Modifiers Regarding the Likelihood of Occurrence and Severity of Herbal-Drug Interactions Likelihood of Occurrence Likely Clinical research indicates that this interaction is likely to occur in most patients. Probable Clinical research or pharmacokinetic studies in humans suggest that this interaction will occur in a significant portion of patients. Possible Unlikely
Clinical research, pharmacokinetic data in humans or animals, or in vitro research suggests that this interaction might occur in some patients. Clinical research, pharmacokinetic data in humans or animals, or in vitro research suggests that this interaction can occur, but is not likely to occur in many patients. Life-threatening or severe impairment is possible. Moderate impairment or significant discomfort is possible.
combination; a serious adverse outcome could occur. Yellow X = Moderate risk; use cautiously or avoid the combination; warn patients that a significant interaction or adverse outcome could occur. Green = Minor risk; be aware that there is a chance of an interaction; advise patients to watch for warning signs of a potential interaction. Note. Adapted from “About Natural Medicines Comprehensive Database,” by the Natural Medicines Comprehensive Database, n.d.a, retrieved from http://naturaldatabase.therapeuticresearch.com/ Content.aspx?cs=&s=ND&page=aboutdbhtml&xsl=generic#ratings
Severity High
Moderate
Mild
Mild impairment or mild discomfort is possible. Insignificant Drug levels may be affected, but a clinically significant interaction is not likely. Note. Adapted from “About Natural Medicines Comprehensive Database,” by the Natural Medicines Comprehensive Database, n.d.a, retrieved from http:// naturaldatabase.therapeuticresearch.com/Content.aspx?cs=&s=ND&page=about dbhtml&xsl=generic#ratings
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