What is the best route of injection for an irritating drug?

• A. Intrathecal
• B. Intravenous
• C. Intraperitoneal
• D. Intramuscular

Answer: (B)

When a drug is irritating to tissues, the aim is to minimize contact with tissues while getting the drug into systemic circulation. Intravenous administration delivers the drug directly into the bloodstream, where it is rapidly diluted and distributed throughout the body. This greatly reduces exposure of muscle, peritoneal lining, or other tissues to the irritant, lowering the risk of local pain, inflammation, or necrosis at the injection site.

Other routes place the drug in contact with tissues: intramuscular injects into muscle, which can become inflamed or damaged by an irritant; intraperitoneal exposes the peritoneal lining to irritation; intrathecal introduces the drug into the spinal canal, which is reserved for specific CNS-targeted therapies and isn’t appropriate for general irritating compounds. Intravenous delivery also allows better control of administration rate, which helps manage the irritant’s systemic effects.