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

- drug of choice for mild-to-moderate Clostridium difficile colitis

- Oral, i/v, cream

SE:

nausea, metallic taste, loss of appetite, stomatitis and headaches

CI:

- early pregnancy

- breastfeeding

-used alone or Combined with ceftriaxone

-T1/2 increase with cimetidine