Pharmacology, Therapeutics, and Medical Emergencies
Core concepts
Pharmacology questions test safe prescribing: indication, dose, route, duration, interactions, and contraindications. Know the common dental drugs - local anaesthetics (lidocaine with adrenaline, articaine, prilocaine), analgesics (paracetamol, ibuprofen, the opioid step), antibiotics (amoxicillin, metronidazole, clindamycin as an alternative in penicillin allergy), antifungals, and antiseptics. Understand maximum safe doses of local anaesthetic, calculated by weight and expressed in milligrams, and the role of adrenaline in prolonging action and reducing systemic absorption.
Learn drug interactions and cautions: metronidazole with alcohol, macrolides and warfarin, NSAIDs in renal disease or asthma, and antibiotic prophylaxis indications for infective endocarditis in high-risk patients. Recognise adverse reactions: local anaesthetic toxicity (perioral tingling, tinnitus, seizures), allergy (rash, angioedema, anaphylaxis), and antibiotic-associated colitis.
Medical emergencies
Know the ABCDE approach and the specific management of syncope, hypoglycaemia, asthma, angina, anaphylaxis, and choking. Adrenaline for anaphylaxis is given intramuscularly into the anterolateral thigh. Oxygen and positioning are often the first steps.
Traps
- Confusing maximum dose calculations with volume.
- Prescribing antibiotics for viral or self-limiting conditions.
- Missing the interaction between metronidazole and alcohol.
- Forgetting that aspirin is not the first-line analgesic in children.
Worked example
A 60 kg patient requires lidocaine 2% with adrenaline. Rule of thumb: maximum dose is about 4.4 mg/kg (up to 7 mg/kg with adrenaline in some guidelines), so 60 x 4.4 = 264 mg. A 2% solution contains 20 mg/mL, so 264/20 = about 13 mL - well above the cartridge volume typically used, which shows how rarely the limit is reached in healthy adults.