Hello dear,

Pharmaceuticals drugs dosages are easily available on internet like drugs.com, pocketpill, Medscape,Lippincott pocket drug guide,FDA regulatory affairs textbook,
But sometimes when you won't have access to Internet and when there is emergency situation, it's better to keep a book handy like KD.TRIPATHI, handbook ,
As it's not always possible to memorise the doses so be careful dear regarding doses and cross check two or three websites and a standard book before prescribing any drug ,

All the best and feel free to ask furthur queries regarding doses of medications ,

I hope the above information is useful to you,

All the best !

Hello Nazeemanuzzhat, You can get the accurate pharmaceutical drug dosages easily on the internet. You just need to google it and there are multiple websites offering drug dosages content. For studying purpose, You can also find accurate dosages in books like: Med notes(by judith hopfer), Drug doses(by Frank shann), Dosage calculation(by gloria pickar).