Phenytoin Toxicity

Question.

216. Granulocytopenia, gingival hyperplasia and facila hirsutism are all possible side effects of one of the following anticonvulsant drugs.

1. Phenytoin.

2. Valproate.

3. Carbamazepine.

4. Phenobarbitone.

Answer

1. Phenytoin.

Reference

Katzung, 7^th Edition Pages 391

KDT 5^th Edition Page 372 & 4^th Edition Page 385

Quality

Spotter – First Clinical

Status

Repeat

QTDF

All books!!

Discussion

The adverse effects of Phenytoin are

1. Gum Hyperplasia

2. Hirsutism, acne

3. Hypersensiticity reactions – rashes, DLE, Lymphadenopathy, neutropaenia which requires discontinuation of therapy

4. Megaloblastic Anemia due to Decreased Absorbtion and Increased Excretion of Folic Acid

5. Granulocytopaenia and even Pancytopaenia

6. Osteomalacia

7. Hyperglycaemia due to inhibition of Insulin release

8. Foetal Hydantoin Syndrome

a. Hypoplastic Phalanges

b. Cleft Palate

c. Hare Lip

d. Microcephaly

Explanation

1. Phenytoin causes all the fetures given above.

2. Valproate causes Fulminant hepatitis and during pregnancy Neural Tube defects in Off Spring.

3. Carbamazepine produces dose related neurotoxicity and hepatitis, lupus like syndrome, rarely agranulocytosis and aplastic anaemia.

4. Phenobarbitone causes rashes, megaloblastic anaemia and osteomalacia.

Comments

Side effects of the drugs are best read from the Table in Harrison

Tips

Note the 5 H in the adverse effects

н Hyperplasia of Gums,

н Hirsutism,

н Hypersensiticity reactions

н Hyperglycaemia

н Hydantoin Syndrome