Formulary Selection for Prescribing Clinicians: Navigating the Cannabis Market

What Is a Cannabis Formulary and Why Does It Matter?

• A formulary is a curated list of approved cannabis products available within a clinic or prescribing network
• Formulary selection ensures quality, traceability, and consistency for patients receiving long-term treatment
• Well-constructed formularies include products from EU-GMP certified cultivators only
• Formularies reduce prescribing variation and support evidence-based practice within clinical teams

The UK medical cannabis market offers a bewildering range of products from dozens of licensed importers. Without a structured formulary, prescribers face the risk of inadvertently recommending products that cannot be sourced, that are not of consistent quality, or that expose patients to products without adequate documentation of cannabinoid and terpene content. A well-designed formulary is therefore a cornerstone of safe and effective cannabis prescribing.

Quality Standards: What to Look for in a Formulary Product

• EU-GMP certification: the gold standard for pharmaceutical cannabis manufacturing globally
• Certificate of Analysis (CoA): provides batch-specific cannabinoid and terpene quantification from accredited laboratories
• Residual solvent, heavy metal, and pesticide testing must be included in every CoA
• Product consistency: acceptable cannabinoid variation within a batch should not exceed ±10% of stated values

EU-GMP (European Union Good Manufacturing Practice) certification is the most reliable indicator of product quality for cannabis-based medicines. Prescribers should insist that all formulary products come with batch-specific CoAs from UKAS-accredited or equivalently recognised laboratories. Products without CoAs or with outdated documentation should not be considered for formulary inclusion.

Building a Balanced Formulary: Strain Categories

• Include at least one balanced CBD:THC product (for cannabis-naive patients and sensitive profiles)
• Include one or two low-potency sativa options for daytime pain, fatigue, and mood indications
• Include one or two moderate-potency indica options for pain-sleep comorbidity
• Include a high-CBD option for patients who cannot tolerate psychoactive preparations

A formulary that covers all major clinical presentations should not require prescribers to go outside approved products. The inclusion of products across the potency and CBD:THC ratio spectrum ensures that clinicians can match the right product to the right patient without compromising on quality or traceability. Products should be reviewed annually and removed if supply reliability, quality documentation, or clinical evidence does not meet the required standard.

Supplier Relationships and Supply Chain Considerations

• Establish direct relationships with licensed importers before building a formulary
• Confirm minimum stock levels and supply continuity commitments — patient discontinuation due to stock failure is a significant clinical and regulatory risk
• Ensure importers hold valid MHRA import licences for each product on the formulary
• Consider patient affordability: price variation between equivalent products can be significant and affects adherence

The practical aspects of formulary management are as important as the clinical and quality dimensions. A clinically excellent product that is frequently out of stock or prohibitively expensive for most patients provides little real-world benefit. Prescribers should engage their clinic’s operations team and, where relevant, their cannabis specialist pharmacy partners to ensure the formulary is both clinically sound and operationally deliverable.