No, you cannot. The biological components of most of the drugs including antibiotics are different, that if given not according to the prescribed route, the bioavailability and mechanisms of action can be altered. For safety and efficacy, oral forms are to be taken by mouth and injectables are to be given by shots.
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For a 1 year old child a G25 needle is usually used to administer intramuscular injection, that needle size is appropriate enough.
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