The CRA framework states that each assessment is likely to include at least one question on specific drugs or drug groups. These are the high-risk medicines — drugs with narrow therapeutic indices, complex monitoring requirements, significant interaction profiles, or serious adverse effects that pharmacists must manage safely.
This is the list you must know cold.
Anticoagulants (Warfarin and DOACs)
Warfarin: INR monitoring. Target range varies by indication (2-3 for AF and DVT/PE; 2.5-3.5 for mechanical heart valves). Interactions: extensive — enzyme inhibitors (amiodarone, fluconazole, erythromycin increase INR), enzyme inducers (carbamazepine, rifampicin decrease INR), cranberry juice, vitamin K-containing foods. Reversal: vitamin K (oral or IV), prothrombin complex concentrate for major bleeding. Counselling: INR monitoring compliance, interaction awareness, yellow anticoagulant booklet.
DOACs (apixaban, rivarelbaban, edoxaban, dabigatran): Renal function monitoring — dose adjustment required in renal impairment (specific to each DOAC). Drug interactions: P-gp inhibitors and CYP3A4 inhibitors. Dabigatran reversal: idarucizumab. Andexanet alfa for factor Xa inhibitors (limited availability). No routine monitoring — but renal function should be checked at initiation and annually.
Insulin
Types: Rapid-acting (lispro, aspart, glulisine), short-acting (soluble/Actrapid), intermediate-acting (isophane/NPH), long-acting (glargine, detemir, degludec), biphasic (mixed preparations). Know the onset, peak, and duration of each.
Safety checks: Ensure correct insulin prescribed (name, device, units). Never abbreviate "units" as "U" (misread as 0). Check device compatibility (pens are not interchangeable between brands). Hypoglycaemia management: know the thresholds and treatment.
Methotrexate
Monitoring: FBC, LFTs, renal function at baseline and regularly during treatment. Pulmonary function if respiratory symptoms develop. Dosing: Once weekly (not daily — daily methotrexate is a potentially fatal dosing error). Folic acid supplementation (5mg once weekly, not on the same day as methotrexate).
The exam trap: The once-weekly dosing error. The CRA may present a scenario where methotrexate is prescribed daily — the correct answer is to identify this as a prescribing error and not supply.
Lithium
Monitoring: Serum lithium levels (12 hours post-dose), renal function, thyroid function, calcium at baseline and every 6 months. Target range: 0.4-1.0 mmol/L (maintenance); 0.8-1.0 mmol/L (acute). Interactions: NSAIDs, ACE inhibitors, diuretics (all increase lithium levels and toxicity risk). Dehydration increases toxicity risk. Toxicity signs: Tremor, nausea, diarrhoea (mild); ataxia, confusion, seizures (severe). Counselling: Maintain fluid intake, avoid dehydration, purple lithium card.
Aminoglycosides (Gentamicin, Amikacin)
Monitoring: Pre-dose (trough) levels. Renal function before and during treatment. Ototoxicity monitoring. Dosing: Once-daily extended-interval dosing now standard for many indications — but dose calculated by weight and renal function. Duration typically limited to minimise toxicity.
Opioids
Dose equivalence: Know the oral morphine equivalence table. Converting between opioids requires understanding equianalgesic doses and incomplete cross-tolerance (reduce the calculated equivalent dose by 25-50% when switching). Constipation: Prescribe a laxative (stimulant ± osmotic) with every opioid prescription. Respiratory depression: Risk factors, monitoring, naloxone availability and dosing.
DMARDs (Disease-Modifying Anti-Rheumatic Drugs)
Monitoring: FBC, LFTs, renal function at baseline and regularly. Drug-specific: sulfasalazine (FBC every 2-4 weeks initially), hydroxychloroquine (ophthalmology screening after 5 years for retinal toxicity), leflunomide (BP monitoring, hepatotoxicity).
How to Prepare
The CRA tests these drugs through applied clinical scenarios — not isolated pharmacology. A question might present a patient on warfarin with a new prescription for fluconazole and ask what the pharmacist should do. Or a patient on lithium presenting to community pharmacy with symptoms of toxicity.
iatroX Q-bank includes questions on every drug class listed above, with BNF-referenced explanations and safety-focused clinical pearls. The adaptive engine concentrates practice on the drug classes you are weakest in.
Start at iatrox.com/quiz-landing?exam=uk-gphc.