sulphonamides, trimethoprim, pyrimethamine and dapson
sulphonamides, trimethoprim, pyrimethamine and dapson Folates are essential for the synthesis of purines and pyrimidines (precursors of RNA and DNA). Therefore, in the absence of folate, cells cannot grow or divide. To synthesize the critical folate derivative (tetrahydrofolic acid) humans must first obtain pre-formed folate in the form of folic acid from the diet. In contrast, many bacteria are impermeable to folic acid and other folates and, therefore, must rely on their ability to synthesize folate de novo.
1. Sulphonamides
- best absorbed orally - reserved for IBD; UC
- In burn victims, creams can be used such as Sulfadiazine, sulfamylon to prevent colonization
- Adverse effects includes *Crystalluria, Allergic Reactions SJS, Hematopoietic;G6PD disturbances; granulocytopenia and thrombocytopenia can also occur, Kernicterus; last 2 weeks of pregnancy, drug potentiation ofwarfarin & super infections
2- Trimethoprim 20-50 folds more potent than sulph
- Penetrates the cerebrospinal fluid
- Mainly for UTI’s, Prostatitis, Vaginitis due - Weak base, higher concentration trapped in prostatic & vaginal fluids - though Quinolones are preferred
- Adverse effects includes hypersensitivity, F.A. deficiency (anemias, leucopenia, granulocytopenia esp. pregnancy and poor diets), also Teratogenic risk in pregnancy
SULFONAMIDES COMBINATIONS:
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CO-TRIMOXAZOLE Co-trimoxazole is a combination of two antibiotics: sulfamethoxazole & Trimethoprim. It is commonly used to treat a variety of bacterial infections such as UTI, certain types of pneumonia, and as a prophylactic treatment for Pneumocystis jirovecii pneumonia in people with HIV/AIDS. Its effectiveness is due to the synergistic action of both antibiotics, inhibiting successive steps in the biosynthesis of nucleic acids and proteins essential to many bacteria.
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sulfadiazine & pyrimethamine (dihydrofolate reductase inhibitor) is the preferred treatment for toxoplasmosis.
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Sulfadoxine & pyrimethamine is used as an Anti-Malarial drug.
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DAPSONE is a sulfone antibiotic that may be tolerated by some patients with TMP/SMX allergies and is often used as an alternative agent for Pneumocystis prophylaxis in these patients. Also in leprosy
In malaria treatment
Antifolate; (pyremethamine,progunail,Sulphonamides):
Therapeutic uses:
- Treatment of acute attack of chloroquine resistant P.falciparum in combination with Quinine
- Chemoprophylaxis in chloroquine resistant P.falciparum
Side effects:
see above drugs side effects