Indications
Demeclocycline Hydrochloride is a tetracycline antibiotic used to treat infections caused by susceptible bacteria, such as some chest, skin, urinary and sexually transmitted infections, and acne. Doctors also use it to treat a condition called SIADH (syndrome of inappropriate antidiuretic hormone), in which the body holds too much water and the blood sodium level falls.
How It Works
As an antibiotic, Demeclocycline stops bacteria from making the proteins they need to grow, by blocking their ribosomes. This stops the bacteria from multiplying so the immune system can clear the infection. In SIADH, it reduces the kidney’s response to antidiuretic hormone, so the kidneys pass more water and the blood sodium rises.
Dosage and Administration
Usual adult dose for infections: 150 mg four times a day or 300 mg twice a day. For SIADH, the dose and length of treatment are decided by the doctor, as prescribed. Take on an empty stomach, at least 1 hour before or 2 hours after food, with a full glass of water, while sitting or standing. Do not lie down for at least 30 minutes after a dose. Complete the full course for infections.
Interactions
- Antacids, Calcium, Iron, Zinc, Magnesium, Bismuth and milk or dairy products reduce absorption: separate doses by at least 2 to 3 hours.
- Warfarin effect may increase; INR should be monitored.
- Isotretinoin and Acitretin increase the risk of raised pressure in the skull; avoid the combination.
- Penicillins may work less well when combined with tetracyclines.
- Methoxyflurane and some diuretics can increase kidney harm.
- Oral contraceptives may be less effective in rare cases; ask your doctor about extra protection.
Contraindications
- Allergy to Demeclocycline or other tetracyclines.
- Children under 12 years, as it can permanently stain developing teeth and affect bone growth.
- Pregnancy and breastfeeding.
- Severe kidney impairment (except under specialist care for SIADH).
- Systemic lupus erythematosus.
Side Effects
Common side effects include nausea, vomiting, diarrhoea, loss of appetite, and a strong sensitivity to sunlight leading to severe sunburn. It can cause increased thirst and passing large amounts of urine (diabetes insipidus effect), which is more likely at higher doses. Other effects include thrush in the mouth or vagina, irritation of the food pipe if taken lying down, and rarely liver problems, raised pressure in the skull, blood disorders or severe skin reactions.
Get urgent medical help if you have a severe headache with blurred or double vision, severe or bloody diarrhoea, yellowing of the skin or eyes, a blistering or peeling rash, swelling of the face or throat, difficulty breathing, or severe pain when swallowing.
Pregnancy and Lactation
Do not use during pregnancy: tetracyclines can harm the unborn baby’s teeth and bones and can harm the mother’s liver. Avoid while breastfeeding, as it passes into breast milk and can affect the baby’s teeth.
Precautions and Warnings
- Avoid strong sunlight and sunbeds; use sun protection, as burns can be severe.
- Tell your doctor if you have kidney or liver disease or myasthenia gravis.
- In SIADH, sodium levels and kidney function are checked regularly.
- Do not use expired tablets.
- Seek advice if diarrhoea develops during or after treatment.
Overdose
Overdose can cause nausea, vomiting, diarrhoea and, in large amounts, liver and kidney damage. Get medical help. Treatment is supportive; antacids or milk given under medical advice may reduce absorption.
Therapeutic Class
Antibacterial, tetracycline group.
Storage
Store below 30°C in a dry place, away from light and out of the reach of children.
Prepared by the Oshud Alo team from standard drug references. For information only; always follow your doctor's advice.