Parenteral delivery involves injecting drugs directly into the body, bypassing the gastrointestinal tract. This allows for rapid drug onset but also increases safety risks. Parenteral routes include intravenous, intramuscular, and subcutaneous injections. The rate and extent of drug distribution throughout the body depends on factors like blood flow, protein binding, and capillary permeability. Tissues like muscle and fat can experience damage from injection due to their vascular and immune responses. Careful consideration of a drug's pharmacokinetics is important for optimizing parenteral delivery.