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68. Sulfonamides, trimethoprim, pyrimethamine. Fluoroquinolones: Difference between revisions

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(Created page with "== Sulphonamides and diaminopyrimidines == Sulphonamides and diaminopyrimidines both act on the folic acid metabolism of bacteria and parasites. They potentiate each other’s actions and are therefore almost always sold in fixed combinations. Here are the most important combinations: {| class="wikitable" !Sulphonamide !Diaminopyrimidines !Name of combination !Effective against |- |Sulfamethoxazole (SMX) |Trimethoprim (TMP) |Co-trimoxazole or Bactrim® or TMP/SMX |Bacter...")
 
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=== Pharmacokinetics and dosing ===
=== Pharmacokinetics and dosing ===
All except sulfadiazine are given orally; sulfasalazine is too but is not absorbed. These drugs have excellent distribution, especially into the lungs, while also crossing the blood-brain barrier and the placenta. They have strong plasma protein binding.
All are given orally (sulfasalazine is too but is not absorbed). These drugs have excellent distribution, especially into the lungs, while also crossing the blood-brain barrier and the placenta. They have strong plasma protein binding.


Most sulphonamides and diaminopyrimidines are metabolised in the liver and excreted by the kidneys. Those drugs given in combination have similar half-lives. Both sulfamethoxazole and trimethoprim have a half-life of 11 hours, for example.
Most sulphonamides and diaminopyrimidines are metabolised in the liver and excreted by the kidneys. Those drugs given in combination have similar half-lives. Both sulfamethoxazole and trimethoprim have a half-life of 11 hours, for example.