Tetracycline Antibiotics

This article deals with the group of antibiotics known as the tetracyclines. For the specific antibiotic called "tetracyclin."

The 4 rings of the basic tetracycline structure.

Tetracyclines are a group of broad-spectrum antibiotics whose general usefulness has been reduced with the onset of bacterial resistance. Despite this, they remain the treatment of choice for some specific indications.

Indication
Tetracyclines may be used in the treatment of infections of the respiratory tract, sinuses, middle ear, urinary tract, intestines, and also gonorrhoea, especially in patients allergic to ?-lactams and macrolides; however, their use for these indications is less popular than it once was due to widespread resistance development in the causative organisms. Tetracycline derivatives are currently being investigated for the treatment of certain inflammatory disorders.

Administration
When ingested, it is usually recommended that tetracyclines should be taken with a full glass of water two hours after eating, and one hour before eating. This is partly due to the fact that tetracycline binds easily with magnesium, aluminium, iron, and calcium, which reduces its ability to be completely absorbed by the body. Dairy products or preparations containing iron are not recommended directly after taking the drug.

Cautions
Tetracyclines should be used with caution in those with liver impairment and may worsen renal failure (except doxycycline and minocycline). Antacids and milk reduce the absoption of tetracyclines. Drugs in the tetracycline class become toxic over time, so expired prescriptions of these drugs should be discarded after the expiration date has passed.

Contraindications
Tetracycline use should be avoided in pregnant or lactating women, and in children with developing teeth because they may result in permanent staining (dark yellow-gray teeth with a darker horizontal band that goes across the top and bottom rows of teeth).

Side effects
Side effects from tetracyclines are not always common, but of particular note is possible photosensitive allergic reaction which increases the risk of sunburn under exposure to UV light from the sun or other sources. This may be of particular importance for those intending to take on holidays. They may cause stomach or bowel upsets, and rarely allergic reactions. Very rarely severe headache and vision problems may occur.

References
1. ^ Bhattacharya SK, National Institute of Cholera and Enteric Diseases (2003). "An evaluation of current cholera treatment". Expert Opin Pharmacother 4 (2): 141-6. PMID 12562304.
2. ^ Parsi VK (2001). "Cholera". Prim. Care Update Ob Gyns 8 (3): 106-109. PMID 11378428.

• British National Formulary 49 March 2005