Description of collaborative, fee-for-service, office-based, pharmacist-directed medical cannabis therapy management service for patients with chronic pain.

BACKGROUND: Treatment with medical cannabis (MC) in the United States tends to be patient-driven in nature despite evidence that suggests that patients have remarkably poor knowledge on the medical use of this treatment modality. OBJECTIVE: To develop and pilot a collaborative, fee-for-service (FFS), office-based, pharmacist-directed MC therapy management (MCTM) service for patients suffering chronic pain. PRACTICE DESCRIPTION: A collaborative, FFS, office-based, pharmacist-directed MCTM service where patients are seen after a physician deems them suitable for treatment with MC. The pharmacist designs the initial treatment regimen by selecting a formulation, dose, route, and frequency of administration and then manages ongoing therapy by making regimen changes based on the patient's response, adverse effects, and financial concerns. PRACTICE INNOVATION: The creation of a specialized service where a registered MC pharmacist is positioned in a collaborating provider's office and sees patients face-to-face for the provision of MCTM services. EVALUATION METHODS: Patient retention, revenue generated, and ability to replicate the service were evaluated. Patient satisfaction was assessed by collecting subjective feedback on the service. RESULTS: The pilot site that developed the service has seen 133 patients from 2016 to 2021 and has retained 89% of patients after 5 years of quarterly appointments. Patients appear willing to pay out of pocket for the service, and the revenue generated covers the pharmacist's and collaborating physician's time as well as additional overhead. The service has been replicated at 2 additional sites, and patient feedback has been positive. CONCLUSIONS: MCTM is another useful pharmacist service that patients are willing to pay for. MCTM services decrease the collaborating provider's workload while still allowing them to offer their patients personalized treatment with MC. In our experience, the service retains patients, generates enough revenue to cover costs, can be replicated, and is well received by patients.

Δ-9-tetrahydrocannabinol dose increase leads to warfarin drug interaction and elevated INR.

OBJECTIVE: We have reported a case of a drug-drug interaction (DDI) involving warfarin and Δ-9-tetrahydrocannabinol (THC) that resulted in a supratherapeutic international normalized ratio (INR) level. The purpose of this case report is to highlight the possibility of a pharmacokinetic DDI between THC and warfarin. CASE SUMMARY: A 67-year-old Caucasian man suffering from chronic pain presented to a dispensary in Buffalo, NY, for a refill of his medical cannabis (MC). The patient asked to speak with the pharmacist, and during their discussion the patient stated that he had a supratherapeutic INR level of 5.2 measured at home with a self-test device. The patient had no evidence of bleeding, and administration of warfarin was held for 2 days before the INR level returned to a normal range. The supratherapeutic level occurred when the patient was self-titrating his dose of THC and scored an 8, or "probable," on the Naranjo Adverse Drug Effect Probability Scale. PRACTICE IMPLICATIONS: Warfarin and cannabinoids such as THC are both metabolized by cytochrome P450 (CYP) isozymes present in the liver and gastrointestinal tract. In the case described, a dose increase of 7.35 mg THC preceded an INR elevation of 5.2, but did not result in any bleeding. These observations are suggestive of a DDI involving warfarin and THC. Clinicians involved with MC should have adequate knowledge of the drugs that act as substrates, inhibitors, and inducers of CYP enzymes, including the major cannabinoids.