TABLE 5.
Interaction between warfarin, PPIs, and cannabis.
| Drugs | Probability | Severity | Observed effects | Patient outcomes | Recommendation | References |
|---|---|---|---|---|---|---|
| Anticoagulants | ||||||
| Warfarin (Victim—CYP2C9 and CYP3A4 inhibition) | Probable | Not applicable | Not reported | A case report of a 67‐year‐old male showed adverse effects of mild dry mouth and transient dizziness. INR levels were measured at 5.2 with a home self‐test device 3 days prior. No bleeding complications were experienced | Routine home INR monitoring is indicated. Patients should receive education on the signs and symptoms of bleeding as well as the actions needed to mitigate bleeding complications | 13 |
| Probable | Not applicable | A non‐linear increase in INR was observed with the up‐titration of CBD oil. INR levels increased from 2.22 (Day 1) to 6.86 (Day 3), followed by a decrease to 4.40 (Day 4) after reducing warfarin dose. A continuous trend of decrease was observed with INR of 1.96 (Day 11) | No bleeding complications were identified in this case report of a 44‐year‐old male. Warfarin dose was reduced by 30% | Increased monitoring of INR levels is warranted during the initiation and up‐titration of CBD. Adjust warfarin dose to maintain INR within therapeutic range when necessary | 14 | |
| PPIs | ||||||
| Omeprazole (CYP2C19 inhibition) | Defined | Not applicable |
No significant difference in oral clearance (CL/F) was noted for THC/CBD spray + omeprazole as compared to THC/CBD spray alone AUC and C max differences were not significant and were affected by interindividual variability. Variation ranges (CV%) of AUC and C max% coefficient when the combination was given: 40%–67% for THC and 11‐OH‐THC; 43%–64% for CBD. CV% observed when THC/CBD spray was administered alone: 48%–69% for THC and 11‐OH‐THC; 74%–98% for CBD THC: No change of time to maximum plasma concentration (T max), similar plasma concentration, 11% decrease of half‐life (t 1/2) when taking omeprazole + THC/CBD spray in comparison with THC/CBD spray alone CBD: Marginally higher plasma concentration (not significant), 5% increase of t 1/2, 9% increase of T max when taking omeprazole + THC/CBD spray in comparison with THC/CBD spray alone 11‐OH‐THC: Marginally lower plasma concentration (not significant), 9% increase of t 1/2, 24% decrease of T max when taking omeprazole + THC/CBD spray in comparison with THC/CBD spray alone |
Adverse effects were mainly related to the nervous system. Dizziness (n = 3) was the most commonly reported symptom when combination treatment was given | No recommendation provided | 11 |
| Laxatives | ||||||
| Not specified | Probable | Not applicable | Signs of accumulation were not evident for THC, CBD, and their metabolites. This was confirmed by data analysis of blood sampling within a six‐month interval | Not reported | No recommendation provided | 15 |