Routes of Drug Administrations – Pharmacology Notes

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
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
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
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.

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