Characteristics of Various Routes of Administration of Drugs (2–6)
| Route | Advantage | Disadvantage |
| Intranasal (e.g., antihistamine) | Rapid delivery and immediate effect. High bioavailability. No first-pass metabolism. Avoids gastric environment. | Local irritation. Limited to small doses and small range of drugs. |
| Sublingual (e.g., nitroglycerin) | Easy and convenient delivery. Rapid delivery and immediate effect. High bioavailability. No first-pass metabolism. Avoids gastric environment. Self-administration. | Changes in absorption if swallowed, chewed, or taken after emesis. |
| Oral/enteral (e.g., captopril) | Easy, reliable, economic, convenient, painless, no infection risk. Self-administration. | First-pass metabolism/elimination decreases bioavailability. Slow delivery and onset of action. Dose form needs to accommodate gastric environment (e.g., transit stomach intact for small-bowel absorption). Bioavailability can be influenced by changes in gut status (e.g., emesis, diarrhea, or constipation). |
| Rectal (e.g., laxatives) | Rapid delivery and immediate effect. High bioavailability. No first-pass metabolism. Avoids gastric environment. Suitable for patients with emesis or otherwise inappropriate oral route. | Unpleasant form of administration, with bacteremia risk for immunocompromised patient. Altered absorption in diarrhea and constipation. |
| Inhalation (e.g., albuterol) | Rapid delivery and immediate effect. High bioavailability. No first-pass metabolism. Avoids gastric environment. Direct delivery to affected tissues. Self-administration. | Local irritation. Limited to small doses and small range of drugs. May require special equipment and decreased efficacy with incorrect use. |
| Intramuscular (e.g., morphine) | Intermediate onset of action. Suitable for oil-based drugs. Easier (less skill) administration than intravenous. | Local edema, irritation, or pain. Slower onset of action. Infection risk. |
| Intravenous (e.g., furosemide) | Rapid delivery and immediate effect. Is 100% bioavailable. No first-pass metabolism. Avoids gastric environment. Controlled drug delivery. | Irritation or pain. Risk of infection. Solution must be dissolved well. Risk of embolism. Action not easily reversed. Rapid onset of toxicity. |
| Subcutaneous (e.g., insulin) | Slower absorption and onset of action. Suitable for oil-based drugs. | Local edema, irritation, or pain. Small volumes. Slow onset of action. Infection risk. |
| Transdermal (e.g., fentanyl) | Easy, reliable, economic, convenient, painless. Enables slow and prolonged drug delivery. No first-pass metabolism. Avoids gastric environment. Self-administration. | Slow onset of action. Local skin reactions can occur. Needs highly lipophilic drugs. |
| Percutaneous (e.g., diclofenac/diclofenac sodium gel) | Easy, reliable, economic, convenient, painless. Suitable for local effect. | Slow onset of action. Local skin reactions can occur. |