Doxycycline protein binding

In a pharmacokinetic study [49], this and related aspects of doxycycline were studied in man. Although the degree of serum protein binding as estimated by these workers was lower than in the report [41] discussed above, the differences seem inadequate to call in question the validity of their conclusions in addition, serum levels and protein binding data are not, of themselves, reliable indicators of therapeutic potential. 

The serum-protein binding ability, which varies between animals and is also influenced by the disease state of the animal, will also determine the free diffusible concentration. This, in turn, will have an effect on the elimination of drug residues as well as on their penetration in eggs or milk. This effect will be more pronounced for drugs with a higher tendency for protein binding such as sulfonamides, doxycycline, and cloxacillin (47). 

Doxycycline (Vibramycin) Long-acting Protein-Binding 25%-92% Half-Life 20 hours PO 100 mg 100-200 mg Twice the first day Once a day thereafter... 

With regard to the effect of plasma protein binding on the choice of sampling site, Toutain and coworkers " reported that plasma drug concentrations of antimicrobial drugs that are >80% bound to plasma protein are unlikely to be representative of tissue concentrations. Those antimicrobial drugs that are highly bound to plasma protein include clindamycin, cloxacillin, doxycycline, and some sulfonamides. ... 

Blank H, Cullen SI, Cataland PM (1968) Photosensitivity studies with demethyl-chlortetra-cycline and doxycycline. Arch Dermatol 97 1-2 Bojs G, Moller H (1974) Eczematous contact allergy to oxytetracycline with cross-sensitivity to other tetracyclines. Berufsdermatosen 22 202-208 Boman G, Nilsson BS, Saerens EJ (1973) Protein binding of rifampicin. Scand J Respir Dis [Suppl] 84 40-44... 

Tetracycline and its derivative doxycycline are antibiotics widely used in the treatment of bacterial infections. They also exert an antimalarial activity. Tetracyclines inhibit the binding of aminoacyl-tRNA to the ribosome during protein synthesis. 

The tetracyclines bind ribosomal proteins and inhibit bacterial protein synthesis. The first tetracycline was discovered in 1948. Tetracyclines are classified as polyketides, and all are either isolated from bacteria or derived from other tetracyclines. Common examples include tetracycline (A.30) and doxycycline (A.31) (Figure A.8). 

Figure 2 (See color insert) Scheme of dual vector transactivation system using tetracycline (or doxycyclin). One vector (Vector I) carries a promoter (large arrowhead) and a gene encoding a transactivator protein (red circle). The second vector (Vector II) carries a site that binds only to the transactivator when it has already bound to tetracycline. When the transactivator/ tetracycline unit has bound, a minimal promoter (arrow) is activated, which results in transcription of the therapeutic gene (green rectangle). This results in production of the therapeutic protein (green circle).

Tetracycline (Achromycin) Doxycycline (Vibramycin) Demeclocycline (Dedomycin) Minocycline (e.g., Minocin) Inhibits protein synthesis. Binds to 30s subunit blocking amino acid-linked tRNA from binding to the A site of the ribosome. Most Staphylococcus and Streptococcus strains, enterics, mycoplasma, spirochetes, rickettsiae. Not DOC for any microorganism. Used for acne and chlamydial infections in teens. 

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