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→Pharmacokinetic Considerations
They are organic acids, hydrophilic and will ionise at physiological pH. They generally have '''poor oral bioavailability''' as they unstable in acid environments. They have a limited volume of distribution (0.2-0.3l/kg), this means the drug is mainly confined to plasma and interstitial space. As the are lipophilic they can't enter cells and won't cross the blood brain barrier, unless it is damaged. They are readily excreted by the kidneys, via tubular secretion in the proximal convoluted tubule. This results in high concentrations of the drug in urine.
They are organic acids, hydrophilic and will ionise at physiological pH. They generally have '''poor oral bioavailability''' as they unstable in acid environments. They have a limited volume of distribution (0.2-0.3l/kg), this means the drug is mainly confined to plasma and interstitial space. As the are lipophilic they can't enter cells and won't cross the blood brain barrier, unless it is damaged. They are readily excreted by the kidneys, via tubular secretion in the proximal convoluted tubule. This results in high concentrations of the drug in urine.
* '''Natural Penicillins''' - unstable in acid. Usual routes of administration: IM, SC and Intramammary
* '''Isoxazoyl Penicillins''' - stable in acid, except methicillin. Food greatly reduces absorption. Routes of admin: PO, IM, IV. Cloxacillin and nafcillin are found in some intramammary preparations.
* '''Aminopenicillins''' - stable in acid, though bioavailability is reduced by food. Routes of admin: IM, SC, IV, PO and intramammary.
* '''Carboxypenicillins''' - unstable in acid. Route of admin: IM or IV.
==Side Effects and Contraindications==
==Side Effects and Contraindications==
==Potential Uses==
==Potential Uses==