29)Tetracyclines Flashcards
Tetracyclines
Contain 4 hydrocarbon rings
Broad-spec antibiotics against G+, G-ve + Protozoa
Classification
- Short acting ⇢ Tetracycline + Oxytetracycline
- Intermediate ⇢ Demeclocycline + Metacycline
- Long lasting ⇢ Doxycycline + Minocycline
Mechanism of action
Inhibit protein synthesis ⇢ Reversibly binding to 30s ribosomal subunit
- Blocks attachment of aminoacyl tRNA to acceptor site on mRNA-ribosome complex
- Bacteriostatic
- Enter bacteria via diffusion + active transport
Drug resistance
- ⇡ efflux via active transport pumps
- ⇣ efflux of tetracycline antibiotic
Pharmacokinetics
- Oral absorption ⇢ may be impaired by food
- Widely distributed in the body
- Moderately bound by serum proteins (40 - 80%)
- Cross placenta + secreted in milk
- Partially metabolised in liver
- Excreted in bile + urine
Side effects
Anorexia
Nausea
Vomiting
Diarrhoea
Damaging to developing teeth + bones
Superinfection
Photo-toxicity
Dizziness
Hepatotoxicity in high doses
Nephrotoxicity
Drug interactions
Inhibit bactericidal effect of penicillins
Milk/Milk products may ⇣ absorption of tetracyclines
Contraindications
Pregnancy
Children under 12
Liver problems
Condition of high fluid pressure in brain
Allergy to tetracyclines
Clinical infections
Atypical pneumonia ⇢ Mycoplasma pneumonia or Chlamydia psittaci
Chlamydial urethritis
Lyme disease
Anthrax
Q-fever
Rickettsia infections - Typhus + rocky mountain spotted fever
Malaria
