TETRACYCLINE
General
- bacteriostatic
- g+ve and g-ve
- anaerobes, rickettsia, chlamydia, mycoplasma, protozoa
- most tetracyclines has similar antibacterial activity --> resistant ones can use doxy
- differences in clinical efficacy are minor - only differences are due to pharmacokinetics
- MOA
- partly passive diffusion; partly active transport into cell
- binds reversibly to 30S subunit of bacterial ribosome
- inhibit protein synthesis
- reduced influx/increased efflux of drug by active transport protein pump
- ribosomal protection
- enzymatic inactivation
- differences in excretion
- minocycline excreted in tears - eradicate carrier state of meningococcal infection
- classified by serum T1/2
- short acting - chlortetracycline, tetracycline, oxytetracycline
- intermediate - demeclocycline, methacycline
- long acting - doxy, minocycline
- drug of choice in atypical infections - mycoplasma, chlamydia, rickettsia, spirochetes
- H. pylori - in combination with other regimens
- Vibrio - cholera
- combined with aminoglycosides --> to treat plague, tularemia, brucellosis
- protozoal infection - E. histolytica, Plasmodium falciparum
SE
- GIT - N/V/D
- Bony structures and teeth - binds to Ca in newly formed bone and teeth - enamel dysplasia + retardation in bone growth - hence never give in <8 yo
- Liver
- Nephrotoxic - renal tubular acidosis, renal injury
- Photosensitization
- Vestibular reaction - dizziness, vertigo, n/v
CHLORAMPHENICOL
- binds to 50S ribosomal subunit - inhibit protein synthesis
- bacteriostatic
- active against rickettsia, NOT chlamydia, also g+ve, g-ve aerobic and anaerobic
Clinical use
- rarely used due to resistance, other alternatives, toxicity
- serious rickettsial infection - typhus, rocky mountain spotted fever
- alternative to B-lactams for meningococcal meningitis for pt with serious allergy
- eye infections - cos of its broad spectrum, penetration of ocular tissue + aqueous humor (*ineffective for chlamydial infection)
SE
- BM suppresion - reversible, dose-related - aplastic anemia (idiosyncratic, irreversible)
- newborn infants lack effective glucoronic acid conjugation mechanism --> accummulate drugs in serum --> grey baby syndrome (vomit, flaccid, hypotherm, gray, shock, collapse)
- GIT - N/V/D
1 comment:
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Thank you once again blog admin.
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