Final answer:
A capsule is predominantly administered orally for convenience in home use, especially for systemic antimicrobial treatments. If oral administration is not suitable, parenteral methods like intravenous injections are used, typically in a healthcare setting.
Step-by-step explanation:
A capsule would typically be administered via the oral route, which is considered convenient for home administration of medication, including antimicrobial treatment of systemic infections. This route is generally preferred as patients can easily take these drugs at home. However, in certain cases where a drug is not absorbed in the gastrointestinal (GI) tract or when a patient cannot take oral medications due to their condition (such as vomiting or intubation), parenteral administration (intravenous or intramuscular injection) may be used, usually in health-care settings. In situations demanding rapid onset of drug action or when high plasma levels are necessary, intravenous administration becomes essential. It should be noted that for home administration of peptides or some vaccines, alternative routes like transdermal or mucosal pathways have been explored, offering the potential for patient-friendly and needle-free options.