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→Pharmacokinetic Considerations
The half-life of NSAIDs is often short, and so dosing is required every 4 to 6 hours. Despite this, the duration of action is quite long: although the drug leaves the plasma rapidly it remains bound to the COX enzyme for more extended periods.
The half-life of NSAIDs is often short, and so dosing is required every 4 to 6 hours. Despite this, the duration of action is quite long: although the drug leaves the plasma rapidly it remains bound to the COX enzyme for more extended periods.
NSAIDs primarily undergo hepatic metabolism, but there is some excretion of unaltered drug in the urine, which is enhanced by an alkaline pH. This is an example of ion trapping: since NSAIDs are weak acids, there is a greater degree of ionisation in an alkaline environment, making it more difficult for the drug to cross membranes and escape back to the circulation.
Non-steroidal anti-inflammatory drugs have a high degree of plasma protein binding (approaching 99%). This means that other highly plasma protein-bound drugs with stronger binding affinities may displace NSAIDs from their binding. This would lead to an increase in circulating free drug levels and hence potential overdose. Although this is a theoretical risk, it has been demonstrated in relation to warfarin administration.
Non-steroidal anti-inflammatory drugs have a high degree of plasma protein binding (approaching 99%). This means that other highly plasma protein-bound drugs with stronger binding affinities may displace NSAIDs from their binding. This would lead to an increase in circulating free drug levels and hence potential overdose. Although this is a theoretical risk, it has been demonstrated in relation to warfarin administration.