The drug of choice in treatment of inflantile spasms is
Infantile spasms:-

West syndrome
Onset : 3-8 months of life
Characterised by combination of salaam spells( sudden dropping of the head and flexion of arms), developmental retardation, hypsarrythmia on ECG.

Causes-

Hypoxic ischemic encephalopathy
Neurocutaneous syndromes
Perinatal infections
Hemorrhage
Injury
Metabolic disorders
Localized structural malformations 
The spasms occur in clusters usually on waking

Drug therapy-

Intramuscular ACTH 40-60 unit per day may be given 4-6 weeks and tgen tapered off.
On the other hand oral prednisolone at 2 mg/ kg / day in divided doses may also be used.
These agents abolish spasms and may result in resolution of hypsarrythmia.
Phenytoin
Phenobarbitone
Carbamazepin
ACTH