Penicillamine 💊
⚠️ Monitor closely for agranulocytosis — patients should report sore throat or fever immediately.
Also watch for proteinuria and signs of renal impairment.
Regular FBC, U&E, and urinalysis are essential during treatment.
📖 About
- Penicillamine is a chelating agent and immunomodulator.
- Formerly used as a DMARD in rheumatoid arthritis, but now rarely used due to toxicity and availability of safer alternatives.
- Still important in Wilson’s disease and cystinuria.
⚙️ Mechanism of Action
- Chelation: Sulphydryl group binds copper, lead, mercury, and cystine → forms soluble complexes excreted in urine.
- Immunomodulation: Alters macrophage activity and gene expression; inhibits collagen cross-linking.
- Forms soluble disulphide complexes with cystine, reducing stone formation in cystinuria.
🩺 Indications
- Rheumatoid arthritis (DMARD): Rarely used now; response in 6–12 weeks.
- Wilson’s disease: Chelates copper, increasing urinary excretion.
- Cystinuria: Prevents cystine stone formation.
- Heavy metal poisoning: Chelation of lead and mercury (specialist use).
🔄 Interactions
- Iron: Oral iron reduces absorption; separate by several hours.
- Should not be used with gold salts, chloroquine, or other marrow-toxic DMARDs (risk of severe dermatitis/bone marrow suppression).
⚠️ Cautions
- Any fever or sore throat → urgent FBC (risk of agranulocytosis).
- Bleeding/bruising → check platelets.
- Neurological weakness/diplopia → possible drug-induced myasthenia gravis.
- Monitor renal function and urinalysis for proteinuria.
🚫 Contraindications
- Penicillin allergy (structural similarity; some cross-reactivity).
- Systemic lupus erythematosus (SLE).
- Pregnancy (teratogenic).
- Renal impairment (drug is renally excreted).
❗ Side Effects
- Haematological: Agranulocytosis, aplastic anaemia, thrombocytopenia.
- Renal: Proteinuria, immune complex nephritis, nephrotic syndrome, Goodpasture’s-like syndrome.
- Dermatological: Morbilliform rash (early), pemphigoid-like rash (delayed), severe exfoliative dermatitis.
- Autoimmune: Drug-induced lupus, myasthenia gravis (autoantibodies).
- Other: Taste disturbance, nausea, diarrhoea, alopecia.
💊 Dose
- Typical dose: 125–2000 mg once daily (start low, titrate up).
- Rheumatoid arthritis: Clinical response may take 6–12 weeks.
- Adjust dose in renal impairment or elderly.
- Vitamin B6 (pyridoxine) supplementation may be required.
- Regular monitoring of FBC, renal function, and urinalysis is mandatory.
📚 References
