- DAPTO_MYCIN(cubacin)_______LINE_ZOLID_______QUINU_PRISTIN/DAFLO_PRISTIN(synercid) ARE ANTIBIOTICS to trat infections caused by gram positive organisms including MRSA(methicillin resistant staph.aureus)and VRE(vancomycin resistant enterocci).
- they all admenstrated by iv infusion or iv injection.
- the daptomycin is cell wall inhibitor while the other two drugs are protein synthesis inhibitor.
- combination in the third (synercid )to get synergetic effect.as bothantibiotic in the synercid drug are bacterostatic but when adminstrated together the combination becomes bactericidal.
- daptomycin is cyclic lipopeptide. see the structure
- see the news about daptomycin in the following links
note about plasma protein binding
the more drug bounded to plasma protein the less frequently to metabolized by liver.
A drug's efficiency may be affected by the degree to which it binds to the proteins within blood plasma. The less bound a drug is, the more efficiently it can traverse cell membranes or diffuse. Common blood proteins that drugs bind to are human serum albumin, lipoprotein, glycoprotein, α, β‚ and γ globulins.
A drug in blood exists in two forms: bound and unbound. Depending on a specific drug's affinity for plasma protein, a proportion of the drug may become bound to plasma proteins, with the remainder being unbound. If the protein binding is reversible, then a chemical equilibrium will exist between the bound and unbound states, such that:
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- Protein + drug ⇌ Protein-drug complex
Notably, it is the unbound fraction which exhibits pharmacologic effects. It is also the fraction that may be metabolized and/or excreted. For example, the "fraction bound" of the anticoagulant warfarin is 97%. This means that of the amount of warfarin in the blood, 97% is bound to plasma proteins. The remaining 3% (the fraction unbound) is the fraction that is actually active and may be excreted.
Protein binding can influence the drug's biological half-life in the body. The bound portion may act as a reservoir or depot from which the drug is slowly released as the unbound form. Since the unbound form is being metabolized and/or excreted from the body, the bound fraction will be released in order to maintain equilibrium.
Since albumin is basic, acidic and neutral drugs will primarily bind to albumin. If albumin becomes saturated, then these drugs will bind to lipoprotein. Basic drugs will bind to the acidic alpha-1 acid glycoprotein. This is significant because various medical conditions may affect the levels of albumin, alpha-1 acid glycoprotein, and lipoproteins.
see the following video about
drug metabolism and distribution
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