Pharmacology
Core Pharmacokinetics & Interactions · Cardiovascular & Lipid Drugs · Endocrine & GI Drugs · Immunosuppressants & Biologics · Psychiatric & Neurological Drugs · Substance Use & Withdrawal · Toxicology & Poisoning · Reproductive & Special Prescribing · Miscellaneous
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Core Pharmacokinetics & Interactions
- Pharmacokinetics: Metabolism — Phase I reactions (oxidation, reduction, hydrolysis) mainly via P450; phase II = conjugation (glucuronidation, sulphatio
- P450 Enzyme System — Cytochrome P450: family of enzymes mainly in the liver, responsible for phase I metabolism; CYP3A4 and CYP2D6 are the mo
- Drugs Affecting Hepatic Metabolism — Liver disease affects drug metabolism: reduced first-pass metabolism, reduced clearance, reduced plasma protein binding.
- Therapeutic Drug Monitoring — Digoxin: take at least 6 hours post-dose (to ensure adequate distribution).
- Prescribing in Renal Impairment — Renal impairment → accumulation of renally-cleared drugs and their metabolites.
Cardiovascular & Lipid Drugs
- Antiarrhythmics: Vaughan Williams Classification — Class I (membrane-stabilising, block Na⁺ channels): Ia prolongs action potential (quinidine, procainamide, disopyramide)
- Antiarrhythmic Drugs: Points of Note — Digoxin: narrow therapeutic index; toxicity → arrhythmias, GI upset, yellow vision (xanthopsia); levels ≥6 h post-dose;
- Diuretics — Loop diuretics (furosemide): inhibit Na⁺-K⁺-2Cl⁻ cotransporter in the thick ascending loop of Henle; side effects — hypo
- Statins — Statins: HMG-CoA reductase inhibitors → ↓ cholesterol synthesis, ↑ LDL receptor expression.
- Aspirin — Aspirin irreversibly blocks COX-1 and COX-2 → ↓ thromboxane A2 in platelets → ↓ platelet aggregation.
Endocrine & GI Drugs
- Oral Hypoglycaemics — Metformin (biguanide): first-line in T2DM — ↓ hepatic gluconeogenesis; side effects GI upset, lactic acidosis (avoid if
- Insulin: Types & Regimens — Rapid-acting analogues (lispro, aspart): onset ~15 min, peak 1 h, duration 3–5 h — given with meals.
- Corticosteroids: Side Effects — Glucocorticoid side effects: weight gain, easy bruising, osteoporosis, diabetes, hypertension, proximal myopathy, thin s
- Bisphosphonates — Bisphosphonates (alendronate, risedronate): adsorb to hydroxyapatite and inhibit osteoclast activity → ↓ bone resorption
- Proton Pump Inhibitors — PPIs (omeprazole, lansoprazole): irreversibly block the H⁺/K⁺ ATPase (proton pump) of the gastric parietal cell.
- Octreotide — Octreotide: long-acting somatostatin analogue; somatostatin (from pancreatic D cells) inhibits growth hormone, glucagon
Immunosuppressants & Biologics
- Methotrexate — Methotrexate: folic acid antagonist — inhibits dihydrofolate reductase → ↓ DNA synthesis.
- Azathioprine — Azathioprine: metabolised to 6-mercaptopurine → purine synthesis inhibitor → immunosuppression.
- Cyclophosphamide — Cyclophosphamide: alkylating agent (cross-links DNA) used in vasculitis, SLE and chemotherapy regimens.
- Sulfasalazine — Sulfasalazine: 5-ASA + sulfapyridine conjugate, cleaved by colonic bacteria; active moiety in IBD is 5-ASA.
- TNF-Alpha Inhibitors — TNF-α inhibitors: infliximab (chimeric monoclonal antibody, IV), adalimumab (fully human, SC), etanercept (fusion protei
- Hydroxychloroquine & Antimalarials — Antimalarials (hydroxychloroquine, chloroquine): accumulate in melanin-containing tissues, especially the retina.
- Immunoglobulins: Therapeutics — IVIG uses: primary/secondary immunodeficiency · ITP (NOT TTP) · myasthenia gravis · Guillain-Barré syndrome · CIDP · Kaw
- Interferons — IFN-alpha (leucocytes): antiviral — hepatitis B & C, Kaposi's sarcoma, metastatic renal cell cancer, hairy cell leukaemi
Psychiatric & Neurological Drugs
- Antipsychotics: Typical — Typical antipsychotics (haloperidol, chlorpromazine): block dopamine D2 receptors.
- Antipsychotics: Atypical — Atypicals (olanzapine, risperidone, quetiapine, clozapine): less extrapyramidal effect than typicals; action includes 5-
- Clozapine — Clozapine: atypical antipsychotic for treatment-resistant schizophrenia.
- Serotonin Syndrome — Serotonin syndrome: excess serotonin activity, usually from combining serotonergic drugs (SSRIs, MAOIs, triptans, tramad
- Neuroleptic Malignant Syndrome — NMS: idiosyncratic reaction to dopamine antagonists (antipsychotics, metoclopramide) — more common in young males.
- SSRIs — SSRIs (fluoxetine, sertraline, citalopram): block serotonin reuptake; first-line for depression and anxiety disorders.
- Tricyclic Antidepressants & Overdose — TCAs (amitriptyline, dosulepin): block noradrenaline/serotonin reuptake; anticholinergic side effects (dry mouth, urinar
- Lithium — Lithium: mood stabiliser — narrow therapeutic index; target 0.5–1.0 mmol/l, sample 12 hours post-dose.
- MAOIs — MAOIs (phenelzine, tranylcypromine, moclobemide): block monoamine oxidase → ↑ noradrenaline, serotonin, dopamine.
- Benzodiazepines — Benzodiazepines: enhance GABA-A receptor activity → sedation, anxiolysis, anticonvulsant, muscle relaxation.
- Antiepileptics: Valproate, Carbamazepine, Phenytoin — Sodium valproate: first-line generalised epilepsy; side effects — teratogenicity (neural tube defects), weight gain, tre
Substance Use & Withdrawal
- Alcohol Withdrawal & Problem Drinking — Withdrawal features start 6–12 hours after last drink; seizures at 12–48 h; delirium tremens at 48–96 h (mortality up to
- Wernicke's Encephalopathy & Korsakoff's — Wernicke's: thiamine (B1) deficiency — classically confusion, ophthalmoplegia (nystagmus), ataxia (the triad; only minor
- Fetal Alcohol Syndrome & Zieve's Syndrome — Fetal alcohol syndrome: growth retardation, characteristic facies (short palpebral fissures, smooth philtrum, thin upper
- Opioids & Opioid Overdose — Opioid side effects: respiratory depression, constipation (tolerance does not develop), sedation, nausea, miosis.
- Cocaine & Ecstasy Poisoning — Cocaine: blocks noradrenaline/dopamine/serotonin reuptake → tachycardia, hypertension, hyperthermia, agitation, chest pa
- Smoking Cessation — NICE first-line options: nicotine replacement therapy (NRT), varenicline, or bupropion — with behavioural support.
Toxicology & Poisoning
- Paracetamol Overdose — Paracetamol → NAPQI (toxic metabolite) overwhelms glutathione → centrilobular hepatic necrosis.
- King's College Criteria — King's College criteria identify paracetamol-induced liver failure patients needing liver transplant referral.
- Aspirin & Salicylate Overdose — Salicylate overdose: mixed picture — respiratory alkalosis (direct medullary stimulation) + metabolic acidosis.
- Ethylene Glycol & Methanol Poisoning — Ethylene glycol (antifreeze) → glycolic/oxalic acid: high anion gap metabolic acidosis, calcium oxalate crystals in urin
- Cyanide Poisoning — Cyanide: inhibits cytochrome oxidase (aerobic respiration) — consider in smoke inhalation (burning plastics) and industr
- Organophosphate Poisoning — Organophosphates: irreversibly inhibit acetylcholinesterase → cholinergic excess (muscarinic + nicotinic + CNS).
- Carbon Monoxide Poisoning — CO: binds haemoglobin with ~240× oxygen affinity → carboxyhaemoglobin → tissue hypoxia.
- Lead, Arsenic & Mercury Poisoning — Lead: abdominal pain, constipation, motor neuropathy (wrist drop), blue lines on gums (Burton's lines), basophilic stipp
- Reye's Syndrome — Reye's syndrome: acute encephalopathy + liver dysfunction in children given aspirin during viral illness.
Reproductive & Special Prescribing
- Combined Oral Contraceptive Pill — COCP: oestrogen + progestogen — inhibits ovulation (mainly progestogen effect on LH/FSH).
- Prescribing in Pregnancy — Generally safe: penicillins, cephalosporins, erythromycin (avoid estolate), most antihypertensives (labetalol, methyldop
- Prescribing in Breastfeeding — Most drugs pass into breast milk to some degree — check before prescribing.
- Eclampsia: Magnesium Sulphate — Eclampsia = seizures in the setting of pre-eclampsia.
- HRT — HRT: oestrogen alone (hysterectomised) or combined oestrogen + progestogen (intact uterus — unopposed oestrogen risks en
Miscellaneous
- Botulinum Toxin (Botox) — Licensed uses beyond cosmetics: blepharospasm · hemifacial spasm · focal spasticity (including post-stroke hand/wrist di
- Drugs Acting on Serotonin Receptors — 5-HT agonists are used ACUTELY in migraine; 5-HT antagonists in prophylaxis.
- Dopamine Receptor Agonists — Indications: acromegaly · Parkinson's disease · prolactinoma/galactorrhoea · cyclical breast disease.
- Motion Sickness — Motion sickness: nausea/vomiting from visual-vestibular sensory mismatch.
- Isotretinoin — Isotretinoin: oral retinoid (13-cis-retinoic acid) for severe acne — ↓ sebum production and sebaceous gland size; two-th
- Antibiotic Guidelines (BNF) — Exacerbation of chronic bronchitis: amoxicillin, tetracycline or clarithromycin.
- Erythema Multiforme, SJS & TEN — Erythema multiforme: target lesions starting on hands/feet, spreading to torso; most common cause HSV; drugs include pen