Drug adminstration routes

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Drug Administration Routes

By:Seragaldin M. AbdulqaderClinical pharmacology for nursesUniversity of Raparin/school of nursingThe lecture for undergraduate students:

2015 -2016

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Definition A route of administration in pharmacology and toxicology is the path by which a drug, fluid, poison, or other substance is taken into the body.

Routes of administration are generally classified by the location at which the substance is applied. Common examples include oral and intravenous administration.

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Definition First Pass Effect:When a drug is administered orally, the drug is absorbed by the mesenteric veins. These veins drain into the portal vein which flows into the hepatic sinusoids.

Half-life: The amount of time required to eliminate 50% of the drug in the body. The half-life can be determined from a semilogy graph of the plasma concentration versus time or it can be calculated from the elimination constant.

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Definition

Pharmacokinetics, sometimes abbreviated as PK that is a branch of pharmacology dedicated to determining the fate of substances administered externally to a living organism via specific route to the drug characteristics.

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PharmacokineticA process which formed from:

Liberation- the process of release of a drug from the pharmaceutical formulation Absorption - the process of a substance entering the blood circulation.

Distribution - the dispersion or dissemination of substances throughout the fluids and tissues of the body.

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PharmacokineticMetabolization (or biotransformation, or

inactivation) – the recognition by the organism that a foreign substance is present and the irreversible transformation of parent compounds into daughter metabolites.

Excretion - the removal of the substances from the body. In rare cases, some drugs irreversibly accumulate in body tissue

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Routes of Administration/Enteral1. Oral route (p.o.):EasyUsually safeEconomical

Limitations/RisksRelatively slowLess predictableFirst pass effectPatient compliance

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Routes of Administration/Enteral2. Sublingual (SL):Rapid responseNo first pass effectBypasses GI acids and enzymes

Limitations/RisksNot used for irritating substancesMany molecules do not penetrate oral mucosa

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Routes of Administration/Enteral3. Rectal (PR):Unconscious patientsVomiting patientsSmall childrenMinimal first pass effectBypasses GI acids and enzymes

Limitations/RisksIrregular and incomplete absorptionNot used for irritating substancesSolutions must be isotonic

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Routes of Administration/Parenteral1. Intravenous (IV):Permits titration of dosageLowest intra-individual variabilityMost rapid response (emergencies)Most suitable for irritating substances and large volumes

Limitations/RisksGreatest risks: overdose, anaphylaxis, infection, embolism,

vascular injury, and phlebitis

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Routes of Administration/Parenteral3. Subcutaneous (s.c.):Slower absorption than i.m.Absorption slowed by vasoconstriction

Limitations/RisksNot used for irritating substancesLarge volumes are painful

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Routes of Administration/Parenteral4. Intraperitoneal (i.p.):Provides large absorbing surfacePrimarily used on lab animals

Limitations/RisksFirst pass effectRisks: adhesions, infection, injury

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Routes of Administration/Parenteral5. Topical: Useful for local effectsPoisons and toxins

Limitations/RisksLeast effective for systemic absorption

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Routes of Administration/Parenteral6. Pulmonary Very rapid absorptionUseful for gases, vapors, aerosols

Limitations/RisksNot used for irritating substancesDifficult to control dose

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Thank you