Routes of Drug Administrations – Pharmacology
A route of administration is the path by which a drug, fluid, poison or other substance is brought into contact with the body.
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Routes of administration | Advantages | Disadvantages |
Intravenous (IV) | Absorption circumvented; Prompt onset; Suitable for large volumes and for irritating substances | Most hazardous (emnolism infection, anaphylaxis); Not suitable for only solutions or poorly hydrophilic substances |
Intramucular (IM) | Absorbtion may be tailored to needs: prompt, from aqueous solution; slow and sustained, From respository formulations. Suitable for moderate volumes, oily vehicles and some irritating substances | Precluded during anticoagulant therapy; May be painful |
Subcutaneous (SC) | Absorption may be tailored to needs: prompt, from aqueous solutions; slow and sustained, from respository formulations. Suitable for some poorly soluble suspensions and for instillation of slow-release implants; self-administration is acceptable | Not suitable for large volumes or irritating substances; Possible pain or necrosis from irritating |
Oral (PO) | Most convenient. Relatively cheap and safe | Variable absorption (potentially slow, erratic and incomplete). First-pass effect may be significant |
Rectal (PR) | Partially avoid first-pass effect. Avoid descruction by gastric acid & digestice enzymes. | May irritate rectal mucosa. Not a well-accepted route. |
Sublingual (SL) | Prompt absorption. Bypassfirst-pass affect (unless ingested) | Inconcenient for long-term use Limited to certain types of drug that can be given in small doses |
Inhalation | Almost instantaneous absorption and very rapid onset. Avoid hepatic first-pass effect. May provide localised effect to lungs with minimal systemic side effect | Difficulty in regulating dose (inhaler); Requires specially equipment for drug delivery |
Transdermal | May provide a sustained effect avoid hepatic first-pass effect | Usually very slow onset. Enhanced absorption and risk toxic effects eith inflamed. Abrabed or burned skin. Drug must be highly lipophilic. |