Tetracycline antibiotics

Tetracyclines is one of the earliest classes of antibacterial preparations which were obtained at the beginning of 1950 years. Currently their application is limited due to resistance of many microorganisms to tetracyclines. The greatest clinical value of tetracyclines (natural and semisynthetic tetracycline doxycycline) consists in management of chlamydial infections, rickettsia, fever, some zoonoses, severe acne.

Action mechanism
Tetracycline possess bacteriostatic action that is associated with suppression of protein synthesis in microbial cells. Tetracycline are specific inhibitors of elongation factors EF-Tu as well as non-enzymatic connection of Aminoacyl-tRNA with 70S ribosomal subunits. Tetracyclines also suppress codon's depending connection of Aminoacyl-tRNA with 30 ribosomal subunits.

Spectrum of activity
Tetracyclines are considered to be antibiotics with a broad spectrum of antimicrobial activity. Among gram-positive cocci - pneumococci are the most sensitive to tetracyclines.
More than 50% of S.pyogenes strains and more than 70% of nosocomial strains of staphylococci, the majority of enterococci are resistant to tetracyclines. Among gram-negative cocci meningococci and M.catarrhalis are the most sensitive.
Tetracyclines act on some gram-positive and gram-negative bacilli including Listeria, H.influenzae, Yersinia, Campylobacter (including H.pylori), Brucella, Bartonella, cholera, inguinal granuloma, anthrax, plague, tularemia. Most strains of E. coli, Salmonella, Shigella, Klebsiella, Enterobacter are resistant.
Tetracyclines are active against spirochetes, Leptospira, Borrelia, Rickettsia, Chlamydia, mycoplasma, actinomycetes. Among the anaerobic flora clostridia (except for C.difficile), P.acnes are resistant to tetracyclines.

Indications

  • Chlamydial infection (psittacosis, trachoma, urethritis, prostatitis, cervicitis)
  • Mycoplasma
  • Borreliosis (Lyme disease)
  • Fever (Q fever, Rocky Mountains spotted fever, typhus)
  • Bacterial zoonoses: brucellosis, leptospirosis, anthrax, plague, tularemia
  • Infections of lower respiratory system: exacerbation of chronic bronchitis, community-acquired pneumonia
  • Intestinal infectious diseases: cholera, yersiniosis
  • Gynecological infections: adnexitis, salpingoophoritis (in severe cases-in combination with β-lactamase, aminoglycoside, metronidazole)
  • Acne rosacea
  • Wound infection associated with animals or insect bites.
  • Sexually transmitted infections: syphilis (if allergic to penicillins), granuloma inguinale, lymphogranuloma venereum
  • Eye infections
  • Actinomycosis
  • Bacillary angiomatosis
  • Eradication of H.pylori in patients with gastric and duodenal ulcer (tetracycline in combination with other medications)
  • Prevention of malaria tropica

Contraindications

  • Hypersensitivity to any of the medication ingredients
  • Children under 8 years of age
  • Renal failure (for tetracycline)
  • Severe liver diseases
  • Pregnancy
  • Breastfeeding

Cautions

  • Allergy. Allergic reactions are cross resistant to all tetracyclines
  • Pregnancy. The use of tetracyclines during pregnancy is not recommended as they pass through the placenta and can cause severe disorders of bone tissue formation
  • Breastfeeding. Tetracyclines penetrate into breast milk and may adversely affect the development of bones and teeth in children
  • Pediatric use. Tetracyclines should not be indicated in children under 8 years of age because they can cause retardation of bone growth, discoloration of teeth, enamel hypoplasia. There are reports of bulging fontanelle in young children treated with large doses of tetracycline
  • Urinary system. Tetracyclines are contraindicated in patients with renal failure
  • Abnormal liver function. Tetracyclines are contraindicated in severe liver problems in relation to risk of hepatotoxicity

Side effects

  • Gastrointestinal tract: pain or discomfort in the abdomen, nausea, vomiting, diarrhea
  • CNS: dizziness, instability, increased intracranial pressure during chronic administration
  • Liver: hepatotoxicity especially in patients with baseline liver problems, pregnancy, rapid administration, renal failure
  • Bones: disorder of bone tissue formation, slowing of linear bones growth
  • Teeth: discoloration, defects of enamel
  • Metabolic disorders: disorder of protein metabolism with a predominance of catabolism, azotemia in patients with renal insufficiency
  • Photosensitivity: skin rash and dermatitis under the influence of sunlight, skin lesions are often combined with nails lesions
  • Allergic reactions: skin rash, urticaria, Quincke's edema, anaphylactic shock
  • Local reactions: thrombophlebitis at injection site
  • Other: glossitis, esophagitis, erosions of the esophagus (usually when taking capsules), pancreatitis, inhibition of normal microflora in the gastrointestinal tract and vagina, superinfection, including oropharyngeal, intestinal and vaginal candidiasis, rarely C.difficile-associated colitis

Interactions
Simultaneously use with antacids containing calcium, aluminum and magnesium, sodium bicarbonate and cholestyramine may decrease their bioavailability due to the formation complexes and increase pH of gastric contents.
Do not combine tetracyclines with iron preparations.
Carbamazepine, phenytoin and barbiturates enhance the hepatic metabolism of doxycycline and reduce its concentration in the blood, which may require dose adjustment of the drug or its replacement by tetracycline.
Tetracyclines decrease the effects of estrogen-containing oral contraceptives.
Tetracyclines may increase the effect of indirect anticoagulants because of inhibition of their metabolism in the liver, which requires close monitoring of prothrombin time.
There are reports that the combination of tetracycline with vitamin A supplements increases the risk of pseudotumor syndrome brain.

Patient Information

  • Oral medications tetracycline should be taken standing up and swallowing whole with a full glass of water to prevent damage of the esophagus (esophagitis, ulceration), and gastrointestinal irritation
  • Tetracycline should be taken on an empty stomach - 1 hour before or 2 hours after eating
  • It is necessary to follow all doctor's recommendation during the treatment, try not to miss a dose and take it at regular intervals. In the case of missing dose take it as soon as possible, do not take two doses at the same time
  • Consult with your doctor if the improvements do not occur within 7 days after beginning the therapy
  • Do not take antacids, calcium-containing supplements, iron supplements, sodium bicarbonate, magnesium-containing laxatives within 1-3 hours before and after taking tetracyclines
  • During treatment tetracyclines are not exposed to direct sunlight
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