Folate synthesis inhibitor
Required for DNA synthesis
PABA
dihydropetroate synthase Sulfonamide
Dihydrofolate
dihydrofolate reductase Trimethoprim
Tetrahydrofolic acid
Sulfonamide static
sulfadiazine , Silver sulfadiazine, sulfasalazine, sulfamethoxazole , Mafenid
-compete with PABA for dihydropetroate synthase so inhibit dihydrofolic acid
-against nocardia, enterobacteriaceae in UTI
-Sulfadiazine + pyrimethamine =toxoplasmosis
-sulfadoxine + pyrimethamine =malaria
- Bind to plasma Protein
-Given orally (except Sulfasalazine)
-i/v used in patient unable to taken oral preparation
-Silver sulfadiazine used in burning with sepsis
-Mafenid used in burn (but pain full)
-Pass CSF, placenta
SE:
1- Crystal urea due to acidity of urine
2-Hypersensitivity
3-Hemolytic anemia in G-6-PD deficiency
4-Kernicterus (in newborn) due displacement of bilirubin from albumin
DIA:
displacement of warfarin, methotrexate
CI:
-newborns
-infant less than 2 month
-pregnancy
Trimethoprim
-inhibit dihydrofolate reductase enzyme so inhibit tetrahydrofolate
-same spectrum of sulfonamide
-potent 20-30 fold
-reach CSF, prostate
SE:
-alone in UTI, prostatitis
-symptoms of folic acid deficiency
(megaloblastic anemia, leucopenia )
Cotrimoxazole: 1/5
- Is combination of trimethoprim with sulfamethoxazole
-have grater antimicrobial activity
MOA:
synergistic antimicrobial effect due to inhibition of 2steps in THFA synthesis
Uses:
-treating prostatitis, UTI, respiratory , GI infection , pneumonia, Listeria, toxoplasmosis, nocardia
SE:
-Dermatological
-GI upset
-Megaloblastic anemia, leukopenia which treated by folinic acid
DIA:
Prolong prothrombin times with warfirin
Inhibit metabolism of phenytoin
Displace Methotrexate by sulfamethoxazole
metronidazole It is on the World Health Organization's List of Essential Medicines
Anti protozoal drug
Mechanism of action:
It inhibits nucleic acid synthesis
Indication:
- giardiasis, trichomoniasis, and amebiasis.
- pelvic inflammatory disease, endocarditis, bacterial vaginosis, fungating wounds , intra-abdominal infections, lung abscess
- Eradicate Helicobacter pylori with other drugs and to prevent infection in people recovering from surgery