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
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Advantages
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Disadvantages
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Intravenous (IV)
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Absorption circumvented;
Prompt onset;
Suitable for large volumes and for irritating substances
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Most hazardous (emnolism infection, anaphylaxis);
Not suitable for only solutions or poorly hydrophilic substances
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Intramucular (IM)
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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
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Precluded during anticoagulant therapy; May be painful
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Subcutaneous (SC)
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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
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Not suitable for large volumes or irritating substances; Possible pain or necrosis from irritating
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Oral (PO)
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Most convenient.
Relatively cheap and safe
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Variable absorption (potentially slow, erratic and incomplete).
First-pass effect may be significant
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Rectal (PR)
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Partially avoid first-pass effect.
Avoid descruction by gastric acid & digestice enzymes.
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May irritate rectal mucosa. Not a well-accepted route.
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Sublingual (SL)
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Prompt absorption. Bypassfirst-pass affect (unless ingested)
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Inconcenient for long-term use
Limited to certain types of drug that can be given in small doses
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Inhalation
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Almost instantaneous absorption and very rapid onset. Avoid hepatic first-pass effect. May provide localised effect to lungs with minimal systemic side effect
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Difficulty in regulating dose (inhaler); Requires specially equipment for drug delivery
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Transdermal
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May provide a sustained effect avoid hepatic first-pass effect
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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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