Trimethoprim when used alone then have bacteriostatic action but when it is used along with sulfa drugs then it show bactericidal action.
P/ D:- The SULFAMETHOXAZOLE stops PABA and the TRIMETHOPRIM part blocks production of tetrahydrofolic acid from dihydrofolic acid by inhibiting the dihydrofolate reductase enzyme.Thus Cotrimoxazole inhibits the FA synthesis.
Cotrimoxazole is the combination of SULFAMETHOXAZOLE+ TRIMETHOPRIM.
It is also a synthetic drug, It has a wide spectrum of activity.
This is same as of sulfonamides but it is used in some other diseases where sulfonamides are not effective,so somewhere this combination is more effective than the sulfonamides.
Contraindications:-
1) Not used in patients who have allergy with sulfa drugs or trimethoprim.
2) Not used in pregnant women
3) Not used in breast feeding mother’s.
4) It is not used in persons who have Anemia due to folate deficiency.
Uses:- It is used in all places where sulfonamides are being used but they are also used against-
1)Salmonella typhi- it is causative agent which cause typhoid.In typhoid,infection occurs at the ileo cecal junction
2) Pneumocystis jerovici- it is responsible for causing pneumonia in the patients who have very weak immune system may be due to some serious illness like AIDS, uncontrolled DM,etc.
Remember Cotrimoxazole is the drug of choice for pneumonia caused by pneumocystis jerovici.
And even sometime Cotrimoxazole is given as Prophylaxis for pneumonia in AIDS patients.
Adverse effects:-
•Anorexia
•Nausea
