Tetracycline antibiotic / off-label SIADH treatment
Demeclocycline hydrochloride
Brand names: Ledermycin
Adult dose
Dose: SIADH (off-label): 600–1,200mg/day in divided doses
Route: Oral
Frequency: BD–QDS
Clinical pearls
- Renal AVP-V2 antagonist effect — used in chronic SIADH unresponsive to fluid restriction
- Society for Endocrinology / RCP hyponatraemia guidance — vaptans (tolvaptan) generally preferred where available
- Specialist endocrinology supervision
Contraindications
- Pregnancy
- Children <12
- Severe hepatic/renal impairment
- Hypersensitivity
Side effects
- Diabetes insipidus (intended in SIADH; unintended in infection use)
- Photosensitivity
- GI upset
- Tooth discolouration in young children
- Pseudotumor cerebri
Interactions
- Cation-containing products (chelation)
- Warfarin
- Penicillins (antagonism)
Monitoring
- Sodium
- Renal function
- LFTs
- Urine output
Reference: BNF; Society for Endocrinology hyponatraemia guidance; RCP; https://bnf.nice.org.uk/drugs/demeclocycline-hydrochloride/. Verify against your local formulary and the latest BNF before prescribing.
Related
Curated clinical cross-links plus same-class fallbacks.
Calculators
- DOAC Score for Selecting Direct Oral Anticoagulant in Non-Valvular AF · Anticoagulation
- Weight-Based Levothyroxine Dose Calculator · Thyroid
- Centor / McIsaac Score for Strep Pharyngitis · Throat
- Hyponatraemia Cause Algorithm · Electrolyte Disorders
- Ho Index for Predicting Response to Medical Therapy in IBD · Inflammatory Bowel Disease
- Deauville Score (5-Point Scale) for Lymphoma Response · Treatment Response
Pathways
- Diabetic Ketoacidosis (DKA) · JBDS 2013 / Joint British Diabetes Societies; NICE NG17
- Adult Hypoglycaemia (Treated Diabetes) · JBDS-IP (2023): Hospital Management of Hypoglycaemia
- Adrenal Crisis · Society for Endocrinology Emergency Guidance (2024)
- Type 2 Diabetes Management · NICE NG28 2022
- Hyperthyroidism Management · BTA / ETA 2018
- Adrenal Insufficiency · Society of Endocrinology / ESE 2016