Oxytetracycline

Oxytetracycline was the second of the broad-spectrum tetracycline group of antibiotics to be discovered.

Additional recommended knowledge

Daily Sensitivity Test

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Essential Laboratory Skills Guide

History

It was first found near Pfizer laboratories in a soil sample yielding the soil actinomycete, Streptomyces rimosus by Finlay et al. In 1953, a celebrated Scottish American biochemist, Robert B Woodward, worked out the chemical structure of Oxytetracycline, enabling Pfizer to mass produce the drug under the trade name, Terramycin. This discovery by Woodward was a major advancement in Tetracycline research and paved the way for the discovery of an Oxytetracycline derivative, Doxycycline, which is one of the most popularly used antibiotics today.

Indications

Oxytetracycline, like other Tetracyclines, is used to treat many infections common and rare (see Tetracycline antibiotics group). Its better absorption profile makes it preferable to tetracycline for moderately severe acne at a dosage of 250-500mg four times a day for usually 6-8 weeks at a time, but alternatives should be sought if no improvement occurs by 3 months.^[1]

It is sometimes used to treat Spirochaetal infection,Clostridial wound infection and Anthrax in patients sensitive to Penicillin. Oxytetracycline is used to treat infections of the respiratory and urinary tracts, skin, ear, eye and Gonorrhoea although the use of Tetracyclines for such purposes has declined in recent years due to large increases in bacterial resistance to this class of drugs. The drug is particularly useful when Penicillins and/or Macrolides cannot be used due to allergy. It may be used to treat Legionnaire's Disease as a substitute for a Macrolide or Quinolone.

Oxytetracycline is especially valuable in treating Non-Specific-Urethritis, LGV, Lyme disease, Brucellosis, Cholera, Plague, Typhus, Relapsing Fever, Tulaeraemia and infections caused by Chlamydia, Mycoplasma and Rickettsia. Doxycycline is now preferred to Oxytetracycline for many of these indications because it has improved pharmacologic features.

The standard dose is 250-500mg six hourly by mouth. In particularly severe infections this dose may be increased accordingly. Occasionally, Oxytetracycline is given by intramuscular injection or topically in the form of creams, ophthalmic ointments or eye drops.

Veterinary indications

Oxytetracycline is used to control the outbreak of American Foulbrood and European Foulbrood in honeybees.

Side effects

Side effects are mainly gastrointestinal and photosensitive allergic reactions common to the tetracycline antibiotics group.
Can also damage calcium rich organs such as teeth and bones although this is very rare, sometimes causes naval cavities to erode, quite common, the BNF suggests that because of this Tetracyclines should not be used to treat pregnant or lactating women and children under 12 except in certain conditions where it has been approved by a specialist because there are no obvious substitutes. Candidiasis (Thrush) is not uncommon following treatment with broad spectrum antibiotics.

Formulation

Tablets containing 250mg Tablets of Oxytetracycline as the dihydrate.

References

1. ^ British National Formulary 45 March 2003