This document discusses sulfonamides, which were the first effective chemotherapeutic agents used to treat bacterial infections. Sulfonamides work by inhibiting the bacterial synthesis of folic acid, which is essential for bacterial growth. They do this by competing with para-amino benzoic acid (PABA) for the folic acid synthetase enzyme. Common side effects include bone marrow suppression, allergic reactions, and crystalluria. Sulfonamides are often used in combination with other drugs to treat infections like typhoid, UTIs, and meningococcal meningitis.

1. Made by
Mahbubur Rahman &Ananta sutradhar
Jagannath university
Mahbub: 01915923493

2.  Antibiotics are the chemical substances obtained from
certain microorganisms(bacteria&fungi) and are used to
kill or inhibit the growth of other pathogenic
microorganism without affecting the host tissues.
 Antibacterial agent:That interfere with the growth and
reproduction of bacteria.
 Antifungal agent:Is a substance that selectively eliminates
fungal pathogens from host with minimal toxicity to the
host.

3. Folic acid synthesis inhibitors
 Folic acid enzymes are necessary for the synthesis of amino
acid,hence necessary for bacterial protein synthesis.
 We shall be discussing some drugs which interfare with the
synthesis of folic acid,these are
1.sulfonamides
2.Trimethoprim

4. Sulfonamides
 Sulfonamides were the first effective chemotherapeutic
agents to be employed systematically for the prevention
and cure of bacterial infection in man.
 Sulfonamides or sulpha drugs are the basis of several group
of drugs.This original anti-bacterial sulfonamide are
synthetic antimicrobial agent that contain the sulfonamide
group.
 Some sulfonamides are also devoid of antimicrobial activity
e.g anticonvulsant sulfiamiame.

5.  The development of sulfonamides,the most profound
therapeutic revolution in the history of medicines.
 Sulfonilamide is first synthesized by a German chemist
Bayer in 1908.

6. Chemistry
 The agent contains sulfonamide group(-SO2NH2) called
para amio benzoic sulfonamide.
 They are white crystalline powder and acidic in nature.(-
SO2NH2) group present in sulfonamide is not essential but
the important feature is that the sulphur is directly linked
to the benzene ring.
 The para NH2 is essential for antimicrobial activity of
sulfonamide.

7.  Sulfonamide is derived from prontosil(prodrug).
 Sulfonamide is the structural analogue of para amino
benzoic acid(PABA)
 It inhibits bacterial folic acid synthesis(competitor of
PABA).
 Bacteriostatic in action(i.e.inhibit bacterial growth)
 Not used as broad spectrum.

9. Pharmacokinetic
 Route of administration: Oral (well
absorbed from upper GIT)
 Disribution:CSF,Placentra(widely disributed) 20-90
percent drugs protein bound.
 Metabolism: Liver(acetylation)
 Exretion:Kidney (tubular secretion &glumerular
filtration)

10. Classification of sulfonamides
1.Agents absorbed rapidly&exreted rapidly
(a)Short acting (b)Intermidiate acting
Sulfisoxazole
Sulfamethizole Sulfamemethoxazole
Sulphasomidine suulfasomizole
Sulphacytine
2.Agents absorbed rapidly but exreted slowly (a)
Long acting (b)Ultra-long acting
Sulfadimethoxine Sulfalene
Sulphaphenazole Sulfadoxin
Sulfamethoxidiazine Sulfasalazine

11. 3. Agents absorbed very poorly: when given orally
Sulfaguanidine
Succinyl-Sulfathiazole
4.Sulfanamide used topically
Sulfacetamides
Sulfafurazole
5.Miscellaneous
Sulfapyridine
sulfadimidine

12. Mechanism of Action
Folic acid is essential for the growth of bacteria.It is a
precursor of purine,which is precursor of DNA&RNA.Para-
amino benzoic acid(PABA) is a precursor of folic acid and
sulfonamide has structural similarity to PABA.
Some bacteria synthesise their own folic acid from PABA.In
this bacteria sulfanamide compete with the PABA for the
enzyme folic acid synthetase and prevent the incorporation
of PABA into folic acid,so folic acid is not synthesized.
As a result bacteria are deprived of folic acid and are unable
to multiply.

13. Sulfonamide overview
Dihydrofolate diphosphate+PABA
- dihydrofolate synthetase
Dihydropteric acid
Dihydrofolic acid or Dihydrofolate
-Dihydrofolate reductase
Tetraydrofolic acid or tetrahydrofolate
Nucleotides(purine & pyrimidines)
Synthesis of DNA & growth of bacteria

14. Indication
Sulfonamide are not usually prescribed alone.Mostly
combination therapy is preferred,however the indication
are
1.Typhoid and paratyphoid fever
2.Acute & chronic urinary tract infection
3.Tropical application for infected burn
4.Meningococcal meningitis(sulfadiazine)
5.Bacillary dysentery
6.Uncomplicated gonorrhoea
7.Dermatitis
8.Gut sterilization

16. Adverse Effects
 On urinary system
Sulfonamides precipitates in acidic urine & form crystal
which pass the urine.Renal
irritation<>crystalluria<>spasmodic pain(renal
colic)<>haematuria<>renal tubular
necrosis<>oliguria<>anuria

17.  On haemopoietic system
1.Bone marrow depression
2.Aplastic anaemia
3.Acute haemolytic anaemia
4.Thrombocytopenia
5.Eosinophilia
7.Agranulocytosis

18.  On gastrointestinal tract
1.Anorexia 2.Nausea
3.Vomiting 4.Diarrhoea
.Hypersensitivity reaction
1.Skin rushes 2.Photosensitivity
3.Exfoliative dermatitis 4.Contact dermatitis
5.Anaphylaxis 6.Steven johnson
syndrome

20. Contraindication
 Absolute contraindication
1.Pregnency
2.Premature infant
Others
1.Renal ipairmant
2.Dehydration

21. Dosage form
For adult:
2-4 gm for the first dose,then 1gm every 4-6 hours
For children:
1.Children 2 month of age ;dose is best on
body weight(34mg/pound)
2. up 2 months Not reccomended

22. Commercial Brand Name in BD
Name Pharmaceutical
1.Sulfatrim Opsonin
2.Septra Orion
3.Bactrim Square