Demeclocycline Capsules: Uses, Dosage & Side Effects
Comprehensive guide to demeclocycline capsules: uses, dosage, side effects, and essential patient information for safe treatment of infections.
Demeclocycline capsules are a tetracycline antibiotic used to treat various bacterial infections and a specific condition involving low sodium levels in the blood known as Syndrome of Inappropriate Antidiuretic Hormone secretion (SIADH).
About demeclocycline capsules
Demeclocycline hydrochloride belongs to the tetracycline class of antibiotics, which work by inhibiting bacterial protein synthesis, thereby preventing the growth and spread of infection-causing bacteria. It is effective against a broad spectrum of gram-positive and gram-negative bacteria. Unlike other tetracyclines, demeclocycline has a unique application in managing SIADH by inducing a state similar to nephrogenic diabetes insipidus, reducing the kidneys’ response to antidiuretic hormone (ADH).
Available as 150mg capsules, this medication is prescribed when other antibiotics may not be suitable or for off-label uses like acne or Lyme disease, though it is less commonly used today due to side effect profiles.
Key facts
- Demeclocycline is a broad-spectrum antibiotic effective against respiratory, urinary, and skin infections.
- It is also used for SIADH treatment by promoting water excretion.
- Capsules must be taken on an empty stomach with plenty of water while upright.
- Not suitable for children under 12 years or pregnant/breastfeeding women.
- Common side effects include nausea, dizziness, and photosensitivity.
When to take demeclocycline capsules
Demeclocycline is indicated for bacterial infections such as pneumonia, genito-urinary infections (e.g., chancroid, non-gonococcal urethritis), rare infections like tularaemia and bubonic plague, and SIADH caused by pituitary tumors or other conditions leading to hyponatremia.
Bacterial infections treated
- Respiratory tract infections: Including pneumonia and bronchitis.
- Genito-urinary infections: Chancroid, non-gonococcal urethritis.
- Skin infections: Acne, though less preferred now.
- Other: Lyme disease, gum disease, malaria (rarely).
SIADH management
In SIADH, demeclocycline helps correct low sodium levels by blocking ADH effects in the kidneys, leading to increased urine output and normalization of serum sodium.
Who can and cannot take demeclocycline capsules
Who can take it
Adults over 12 years with bacterial infections or SIADH, provided they do not have contraindications. It may be used cautiously in patients with mild liver or kidney issues.
Who cannot take it
- People with hypersensitivity to demeclocycline, tetracyclines, or excipients.
- Those with acute porphyria.
- Patients with severe kidney problems.
- Children under 12 years.
- Pregnant women (risk of fetal harm, tooth discoloration).
- Breastfeeding mothers (passes into milk).
How to take and when to take demeclocycline capsules
Always follow your doctor’s instructions. Capsules should be swallowed whole with a full glass of water while sitting or standing to prevent esophageal irritation.
Dosage guidelines
| Condition | Adult Dosage | Frequency |
|---|---|---|
| Most infections | 600mg/day (4 x 150mg) | 2 twice daily or 1 four times daily |
| Pneumonia | 900mg/day (6 x 150mg) | 2 three times daily |
| SIADH (initial) | 900-1200mg/day | Divided doses |
| SIADH (maintenance) | 600-900mg/day | Divided doses |
| Gonorrhea (penicillin-sensitive) | 600mg initial, then 300mg | Every 12 hours |
Pediatric (over 8 years): 7-13 mg/kg/day, max 600mg/day, divided doses.
Timing and administration
- Take on an empty stomach: 1 hour before or 2 hours after meals, dairy, or antacids.
- Complete the full course even if feeling better.
- If missed: Take as soon as remembered, but skip if almost time for next; do not double dose.
- For renal/liver impairment: Reduce dose or extend intervals.
Common questions about demeclocycline capsules
How long does it take to work?
Improvement in infections may occur within 48-72 hours, but continue the full course. For SIADH, sodium levels may normalize over days to weeks.
Can I take it with food?
No, food, dairy, and certain minerals reduce absorption significantly.
Precautions and warnings
Inform your doctor of conditions like myasthenia gravis, SLE, or liver/kidney disease. Avoid sun exposure due to photosensitivity risk.
- Pseudotumor cerebri: Headache, blurred vision—stop and seek medical help.
- CDAD: Diarrhea may indicate C. difficile—report immediately.
- Driving: Dizziness or vision issues may impair ability.
Drug interactions
Demeclocycline interacts with many substances reducing absorption or efficacy:
- Antacids (aluminum, magnesium, calcium).
- Iron, zinc, strontium ranelate.
- Kaolin, oral typhoid vaccine.
- Warfarin, carbamazepine (monitor levels).
Pregnancy, breastfeeding, and fertility
Not recommended in pregnancy (Category D: fetal bone/teeth risks). Avoid breastfeeding as it passes into milk. May affect male fertility temporarily.
Side effects of demeclocycline capsules
Most are mild, but serious ones require immediate attention.
Serious side effects
- Allergic reactions: Rash, swelling, anaphylaxis.
- Severe skin: Blistering, SJS.
- Renal: Nephrogenic DI, acute failure.
- Neurological: Pseudotumor cerebri, intracranial hypertension.
- Hematologic: Anemia, thrombocytopenia.
Common side effects
- Gastrointestinal: Nausea, vomiting, diarrhea, heartburn.
- Neurological: Dizziness, headache, vision/hearing changes.
- Skin: Photosensitivity, rash.
What happens if you take too much?
Overdose may cause nausea, vomiting, diarrhea, or severe complications. Seek emergency help and inform medical staff.
Frequently Asked Questions (FAQs)
Can children take demeclocycline?
Not under 12 years; for 8-12 years, only under strict medical supervision due to tooth development risks.
Does demeclocycline cause photosensitivity?
Yes, avoid excessive sunlight and use sunscreen to prevent severe sunburn.
How should demeclocycline be stored?
Store below 25°C, away from moisture and light. Discard after expiration.
Can I drink alcohol with demeclocycline?
No specific interaction, but avoid as it may worsen side effects like dizziness.
Is demeclocycline used for acne?
Yes, though other tetracyclines are preferred due to side effects.
References
- Demeclocycline Hydrochloride 150mg Capsules Patient Information Leaflet — Accord Healthcare Limited. 2023. https://www.medicines.org.uk/emc/files/pil.499.pdf
- Demeclocycline Hydrochloride Tablets USP Label — U.S. Food and Drug Administration (FDA). 2012-05-01. https://www.accessdata.fda.gov/drugsatfda_docs/label/2012/050261s101lbl.pdf
- Demeclocycline Tablets — Cleveland Clinic. 2024. https://my.clevelandclinic.org/health/drugs/19676-demeclocycline-tablets
- Demeclocycline — MedlinePlus, U.S. National Library of Medicine. 2023-10-15. https://medlineplus.gov/druginfo/meds/a682103.html
- Demeclocycline 150 mg Tablet — Kaiser Permanente. 2024. https://healthy.kaiserpermanente.org/health-wellness/drug-encyclopedia/drug.demeclocycline-150-mg-tablet.183851
- Demeclocycline: Uses, Side Effects, Dosage — DrugBank Online. 2025-01-01. https://go.drugbank.com/drugs/DB00618
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