Tetracyclines are broad-spectrum antibiotics derived from Streptomyces bacteria. They work by inhibiting the synthesis of bacterial proteins. Tetracycline and the related compounds doxycycline, minocycline and tigecycline alleviate chronic inflammatory airway conditions such as cystic fibrosis (CF).

History of tetracyclines

The first tetracycline, chlortetracycline, was discovered in 1948. Others that have been developed include oxytetracycline, tetracycline, demeclocycline, doxycycline, and minocycline. Oxytetracycline is not available in the United States, however.

Further research led to the development of glycylcyclines, the first of which was tigecycline.

Doxycycline is one of the most active tetracyclines. Its advantages over tetracycline and minocycline mean it’s used more than they are. Doxycycline can be administered two times a day, orally or intravenously. It is less likely to cause photosensitivity, or reaction to light. It can be a good alternative for children because it binds to calcium less than tetracycline, which can discolor teeth and impair bone growth.

How tetracyclines work

Tetracyclines enter the bacterial cell wall in two ways: by passive diffusion and through an energy-dependent active transport system. Once in the cell, they work by binding to the 30S ribosome of microbial RNA, preventing the transfer RNA from attaching to the site that accepts the 70S ribosome. Tetracyclines prevent the growth and spread of bacteria but don’t kill them.

Other details about tetracyclines

Tetracycline, doxycycline and minocycline can be taken orally, or by intravenous or muscle injection. Common side effects are gastric problems such as upset stomach and diarrhea, itching of the rectum or vagina, a sore mouth, skin redness and changes in skin color.

Tigecycline is an injection used to treat serious infections. More patients treated with it have died than those who took other medications for serious infections, according to clinical studies. The deaths occurred when patients’ infections worsened or they developed complications due to other health conditions. Talk to your doctor about the risk of tigecycline.

 

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