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.
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.
Erythromycin is a macrolide antibiotic that has an antimicrobial spectrum similar to or slightly wider than that of penicillin, and is often used for people that have an allergy to penicillins. For respiratory tract infections, it has better coverage of atypical organisms, including mycoplasma and Legionellosis. It is also used to treat outbreaks of chlamydia, syphilis, acne, and gonorrhea. In structure, this macrocyclic compound contains a 14-membered lactone ring with ten asymmetric centers and two sugars (L-cladinose and D-desoamine), making it a compound very difficult to produce via synthetic methods.
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.
Erythromycin is available in enteric-coated tablets, slow-release capsules, oral suspensions, ophthalmic solutions, ointments, gels, and injections.
Brand names include Robimycin, E-Mycin, E.E.S. Granules, E.E.S.-200, E.E.S.-400, E.E.S.-400 Filmtab, Erymax, Ery-Tab, Eryc, Erypar, EryPed, Eryped 200, Eryped 400, Erythrocin Stearate Filmtab, Erythrocot, E-Base, Erythroped, Ilosone, MY-E, Pediamycin, Zineryt, Abboticin, Abboticin-ES, Erycin, PCE Dispertab, Stiemycine and Acnasol.
Erythromycin may possess bacteriocidal activity, particularly at higher concentrations. The mechanism is not fully elucidated however. By binding to the 50S subunit of the bacterial 70S rRNA complex, protein synthesis and subsequently structure/function processes critical for life or replication are inhibited. Erythromycin interferes with aminoacyl translocation, preventing the transfer of the tRNA bound at the A site of the rRNA complex to the P site of the rRNA complex. Without this translocation, the A site remains occupied and thus the addition of an incoming tRNA and its attached amino acid to the nascent polypeptide chain is inhibited. This interferes with the production of functionally useful proteins and is therefore the basis of antimicrobial action.
Erythromycin Ethyl Succinate
Erythromycin is easily inactivated by gastric acid; therefore, all orally-administered formulations are given as either enteric-coated or more-stable laxatives or esters, such as erythromycin ethylsuccinate. Erythromycin is very rapidly absorbed, and diffuses into most tissues and phagocytes. Due to the high concentration in phagocytes, erythromycin is actively transported to the site of infection, where, during active phagocytosis, large concentrations of erythromycin are released.
Roxithromycin is a semi-synthetic macrolide antibiotic. It is used to treat respiratory tract, urinary and soft tissue infections. Roxithromycin is derived from erythromycin, containing the same 14-membered lactone ring. However, an N-oxime side chain is attached to the lactone ring. It is also currently undergoing clinical trials for the treatment of male-pattern hair loss.
Roxithromycin is available under several brandnames, for example Surlid, Rulide, Biaxsig, Roxar and Roximycin. Roxithromycin is not available in the United States. Roxithromycin has also been tested to possess antimalarial activity.