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Demeclocycline 💊
Always check the BNF link here 📖 for full prescribing advice.
- Demeclocycline is a tetracycline antibiotic that is rarely used as an antimicrobial today, but has a role in treating SIADH (syndrome of inappropriate ADH secretion) when other measures fail.
⚙️ Mode of Action
- Inhibits ADH action at the renal collecting ducts, thereby inducing a form of nephrogenic diabetes insipidus 💧.
- This reduces water reabsorption and corrects dilutional hyponatraemia.
💊 Indications & Dose
| Indication | Dose / Frequency | Route |
|---|---|---|
| SIADH (when water restriction not tolerated or ineffective) | 300–600 mg twice daily | PO |
💡 Not a first-line option - typically considered when fluid restriction fails and before vasopressin receptor antagonists are available.
⚠️ Interactions
- See BNF - as with other tetracyclines, absorption is reduced by iron, calcium, magnesium, and antacids.
- May potentiate nephrotoxic effects with other renal-acting drugs.
🔎 Cautions
- Monitor renal function and sodium closely 🧪.
- Use with caution in patients with liver or kidney disease.
- As with other tetracyclines: risk of oesophageal irritation - advise to take with water and remain upright for 30 mins after dose.
🚫 Contraindications
- Pregnancy (risk of fetal tooth/bone abnormalities 👶).
- Children <12 years (causes permanent tooth discolouration).
- Severe renal impairment (risk of toxicity).
❗ Side Effects
- Nephrotoxicity → risk of AKI 🩺.
- Photosensitivity reactions ☀️.
- GI upset: nausea, diarrhoea, oesophagitis 🤢.
- Rare: hepatotoxicity, hypersensitivity reactions.
📚 References
- BNF - Demeclocycline
- UK Renal Association Guidelines - Hyponatraemia management
📝 Revisions
- Expanded mode of action, added monitoring pearls and side effects.
| The content on this website is provided for educational and informational purposes only to support exam preparation (e.g., MLA, MRCP, USMLE) and learning. This is NOT medical advice, diagnosis, treatment, or professional guidance. It does not replace consultation with a qualified healthcare professional, official guidelines (e.g., NICE, GMC, BNF), or supervised clinical practice. Always verify information with current, authoritative sources. Makindo and its contributors accept no liability for any reliance on this content, including errors, omissions, or any resulting harm, loss, or consequences. By using this site, you agree to these terms. |
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