Acyclovir Brand name - Zovirax Acyclovir is an anti-viral drug. It is used to treat infection caused by herpes virus. Used in treatment of genital herpes, cold sore, chicken pox, shingles. It slows...
It all depends what you are measuring. If the substance is denser, than 400 mg will be less volume than if it is very light.
Think of 400 mg of lead vs 400 mg of cotton candy. They are the same...