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Sulphonamides (view source)

Revision as of 12:37, 24 October 2008

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→‎Pharmacokinetic Considerations

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==Pharmacokinetic Considerations==

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* Sulphonamides are lipophilic weak acids of varying pKas.

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Sulphonamides~~: Lipophilic~~ weak acids of varying ~~pKa~~.

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* Most are absorbed readily from the gut, except Succinylsulphathiazole and Phthalylsuphathiazole.

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~~• 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.

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~~• 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%.

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~~• 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.

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~~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==

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