<unk> , like other tetracycline antibiotics, is bacteriostatic. It works by preventing bacteria from reproducing through the inhibition of protein synthesis.<unk>  is highly lipophilic so can easily enter cells, meaning the drug is easily absorbed after oral administration and has a large volume of distribution. It can also be re-absorbed in the renal tubules and gastrointestinal tract due to its high lipophillicity so has a long elimination half life, and does not accumulate in the kidneys of patients with kidney failure due to the compensatory excretion in faeces.<unk> –metal ion complexes are unstable at acid pH, therefore more<unk>  enters the duodenum for absorption than the earlier tetracycline compounds. In addition, food has less effect on absorption than on absorption of earlier drugs with<unk>  serum concentrations being reduced by about 20% by test meals compared with 50% for tetracycline. Mechanism of action<unk>  is a broad-spectrum antibiotic. It inhibits the synthesis of bacterial proteins by binding to the 30S ribosomal subunit, which is only found in bacteria. This prevents the binding of transfer RNA to messenger RNA at the ribosomal subunit meaning amino acids cannot be added to polypeptide chains and new proteins cannot be made. This stops bacterial growth giving the immune system time to kill and remove the bacteria. Pharmacokinetics The substance is almost completely absorbed from the upper part of the small intestine. It reaches highest concentrations in the blood plasma after one to two hours and has a high plasma protein binding rate of about 80–90%.<unk>  penetrates into almost all tissues and body fluids. Very high concentrations are found in the gallbladder, liver, kidneys, lung, breast milk, bone and genitals; low ones in saliva, aqueous humour, cerebrospinal fluid (CSF), and especially in inflamed meninges. By comparison, the tetracycline antibiotic minocycline penetrates significantly better into the CSF and meninges.<unk>  metabolism is negligible. It is actively excreted into the gut (in part via the gallbladder, in part directly from blood vessels), where some of it is inactivated by forming chelates. About 40% are eliminated via the kidneys, much less in people with end-stage kidney disease. The biological half-life is 18 to 22 hours (16±6 hours according to another source) in healthy people, slightly longer in those with end-stage kidney disease, and significantly longer in those with liver disease.
Doxycycline
Oxytetracycline
Amikacin
Streptomycin
Eravacycline
Minocycline
Secnidazole
Sarecycline