Tetralysal Mechanism of Action

Antibacterial.
Pharmacology: Effects on acne: The exact mechanisms by which tetracyclines reduce lesions of acne vulgaris have not been fully elucidated; however, the effect appears to result in part from the antibacterial activity and anti-inflammatory activity of the drugs. Following oral administration, the drugs inhibit the growth of susceptible organisms (mainly Propionibacterium acnes) on the surface of the skin and reduce the concentration of free fatty acids in sebum. The reduction in free fatty acids in sebum may be an indirect result of the inhibition of lipase-producing organisms which convert triglycerides into free fatty acids or may be a direct result of interference with lipase production in these organisms. Free fatty acids are comedogenic and pro inflammatory and are believed to be a possible cause of inflammatory lesions, e.g. papules, pustules, nodules, cysts, of acne. However, other mechanisms also appear to be involved because clinical improvement of acne vulgaris with oral tetracycline therapy does not necessarily corresponds with a reduction in the bacterial flora of the skin or a decrease in the free fatty acid content of sebum.
Tetracyclines provide bacteriostatic action at the available plasma and tissue concentrations and rare effective against intracellular and extracellular organisms. Their mechanism of action is based on an inhibition of ribosomal protein synthesis. Tetracyclines block the access of the bacterial aminoacyl-tRNA to the mRNA-ribosome complex by binding to the 30S subunit of the ribosome, thus preventing the addition of amino acids to the growing peptide chain in protein synthesis. When given at therapeutically attainable concentrations their toxic effects is limited to the bacterial effects.
Pharmacokinetics: Absorption: Absorption is rapid, effective plasma levels are reached within the first hour following drug intake. The peak plasma level is reached within 3 to 4 hours after oral administration. Concurrent milk has not been shown to significantly modify the absorption of lymecycline.
Distribution: Oral administration of 300 mg, in the adult, gives rise to: a peak plasma level of 1.6 to 4 ug/mL, a highly variable residual concentration (0.29 to 2.19 ug/mL), a plasma half-life of approximately 10 hours.
Repeated administration results in a steady mean plasma concentration between 2.3 to 5.8 ug/mL. Wide intra- and extra-cellular diffusion, under normal dosage conditions, results in effective concentrations in most body tissue and fluids, and notable in the lungs, bones, muscles, liver, bladder, prostate, bile and urine.
Excretion/elimination: The product is principally excreted in urine and secondarily in the bile. About 65% of the administered dose are eliminated within 48 hours.