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==Pharmacokinetic Considerations==
 
==Pharmacokinetic Considerations==
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* Sulphonamides are lipophilic weak acids of varying pKas.  
Sulphonamides: Lipophilic weak acids of varying pKa.
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* Most are absorbed readily from the gut, except Succinylsulphathiazole and Phthalylsuphathiazole.
• Orally active. Extent of plasma protein binding varies between individual drugs and between species.
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* They tend to distribute widely throughout the body as the non-ionised form is able to cross cell membranes.
• Generally distribute very widely in body.
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* The extent of binding to plasma proteins is very dependent on the individual drug and species involved and can vary between 20 and 90%.
• Rate of metabolism and rate of renal excretion varies with species and with urine pH.
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* They are eliminate both by hepatic metabolism and renal excretion, the rate of both in each species and for each drug varies. This results in very different half-lives of each drug in each species.  
Not actibe in pus
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* They are unable to work in pus or tissue debris as they contain thymidine and purines. This means that the bacteria can utilise these rather than folic acid for continued growth. This means that the drug will become obselete in such a circumstance.
    
==Side Effects and Contraindications==
 
==Side Effects and Contraindications==
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