What is a recommended dosing regimen for cannabis and Tetrahydrocannabinol (THC) therapy?

Cannabis and THC Dosing Regimen Recommendations

For cannabis and THC therapy, the recommended approach is to start with the lowest possible dose and increase gradually with sufficient time between doses to gauge effects, following a "start low, go slow" principle to minimize adverse effects. 1

General Dosing Principles

• Begin with the lowest possible dose and titrate slowly upward based on clinical response and tolerability 1, 2
• Allow sufficient time between dose increases to properly assess effects, as oral THC onset may take 30 minutes to 2 hours 1
• Avoid taking cannabis products with high-fat meals, as this significantly increases cannabinoid absorption and may exacerbate side effects 1, 2
• Be cautious about "stacking doses" (taking additional doses before the first has taken effect), which can lead to excessive adverse effects 1

Specific Dosing Recommendations

For Oral THC/Dronabinol:

• Starting dose: 2.5 mg orally twice daily (typically one hour before lunch and dinner) 3
• For elderly patients or those unable to tolerate twice daily dosing, begin with 2.5 mg once daily in the evening or at bedtime 3
• Titration: If tolerated and further therapeutic effect is desired, gradually increase to 2.5 mg before lunch and 5 mg before dinner 3
• Maximum dose: 10 mg twice daily 3

For Chemotherapy-Induced Nausea/Vomiting:

• Starting dose: 5 mg/m² orally 1-3 hours before chemotherapy, then every 2-4 hours afterward for a total of 4-6 doses per day 3
• For elderly patients, consider starting at 2.5 mg/m² once daily 3
• Maximum dose: 15 mg/m² per dose for 4-6 doses per day 3

For Oral CBD:

• Avoid doses of 300 mg or more per day due to risk of reversible liver enzyme abnormalities 1
• For patients with epilepsy, CBD has shown efficacy but specific dosing should be determined based on the approved product 4

For Cannabis Extract (1:1 THC:CBD ratio):

• For refractory nausea/vomiting: 1-4 self-titrated capsules of oral THC 2.5 mg:CBD 2.5 mg three times daily 1
• Begin one day before anticipated nausea-inducing event (e.g., chemotherapy) and continue for 5 days after 1

Dosing Considerations for Specific Patient Populations

Perioperative Patients:

• For patients consuming >1.5 g/day of inhaled cannabis, >300 mg/day CBD oil, or >20 mg/day THC oil, consider:
  • Additional anesthetic requirements during induction and maintenance 1
  • Higher postoperative analgesic requirements 1
  • Additional PONV prophylaxis 1

Elderly Patients:

• Start with lower doses (e.g., 2.5 mg once daily for dronabinol) 3
• Monitor more closely for adverse effects due to reduced drug clearance 2

Monitoring and Safety

• Monitor for common adverse effects including euphoria, drowsiness, dizziness, vertigo, and hallucinations 1
• Be aware of potential drug interactions, particularly with medications metabolized by CYP3A4, CYP2C9, and CYP2C19 1, 2
• High-risk drug interactions include warfarin (very high risk), buprenorphine, and tacrolimus (high risk) 1
• Screen patients for psychiatric history before initiating treatment, as THC can exacerbate mania, depression, or schizophrenia 3
• Reduce dose or discontinue if signs of cognitive impairment develop 3

Cautions and Contraindications

• Avoid use in adolescents and young adults due to risk of adverse neurodevelopmental outcomes 4, 5, 6
• Use with caution in patients receiving immunotherapy due to potential interference with treatment efficacy 1
• Avoid use in pregnant women due to risks of small for gestational age and low birth weight outcomes 4
• Avoid use in patients prone to or with existing mental health disorders 4, 5
• Do not use before or while driving due to increased risk of motor vehicle accidents 4, 5

By following these dosing guidelines and monitoring protocols, clinicians can help optimize therapeutic benefits while minimizing potential adverse effects of cannabis and THC therapy.