Dynapen is a brand name for the antibiotic drug dicloxacillin. It belongs to the class of penicillin antibiotics and is mainly used to treat bacterial infections like skin or respiratory infections. However, there are several synonyms available for this drug, which include Dycill, Pathocil, and Oxacillin. These drugs are also a part of penicillin antibiotics and have similar indications of use as Dynapen. Therefore, doctors can prescribe these drugs as a substitute if Dynapen is not suitable or available for the patient. It is important to follow the prescribed dosage and complete the full course of antibiotics to avoid the development of antibiotic resistance.