IV, IM, PO Advantages/Disadvantages

Oral barriers to absorption

Two barriers to cross: -Epithelial cells that line GI Tract** -Drug must PASS THROUGH cells -Absorption may be reduced by P-glycoprotein -Capillary wall

IM advantages

permits use of poorly soluble drug, permits use of Depot preparations

IV advantages

- results in rapid onset of action especially in emergency situations - we have better control of dosage while administering the medication - able to administer larger volumes only through parenteral route - permits use of an irritant drugs because some drugs may be chemically reactive and may cause severe local injury

SubQ advantages

-Can be used for drugs that are poorly soluble -Depot preparations

IM barriers to absorption

-Capillary wall -No significant barrier

SubQ barriers to absorption

-Capillary wall -No significant barrier

SubQ disadvantages

-Discomfort -Inconvenience -May cause local tissue injury -Cannot be used for patients on anticoagulants -Volume restrictions

Oral advantages

-Easy Convenient -Preferred route for self- administration -Safer than injection No risk of: -Fluid overload Infection Embolism -Potentially reversible (safer)

When is IV preferred to PO?

-Emergencies -Where drug levels must be tightly controlled -Treatment that would be destroyed by gastric acidity, digestive enzymes or hepatic enzymes -Whereby po would cause severe local injury -Treating a systemic disorder where other drugs cannot cross membranes -Depot preparation may be desirable -Patients who cannot or will not take po drugs

IV absorption pattern

-Instantaneous -Complete

IM absorption pattern

-Rapidly or slowly Determined by: -Water solubility of drug -Blood flow at site of injection

SubQ absorption pattern

-Rapidly or slowly Determined by: -Water solubility of drug -Blood flow at site of injection

How is "sustained release" oral medications administered?

-Slowly release their medication over a period of time -Don't crush -Generally comes in capsule form -Don't pour into cup -Each tiny particle inside has different release type, others don't have any medication in it

Oral absorption pattern

-Solubility/stability -Gastric and intestinal pH Gastric emptying time -Food - some drugs work better with food; others on an empty stomach -Other drugs Coating on drug

Oral disadvantages

-Variability -Inactivation of other drugs -Requires a conscious and cooperative patient -Local irritation of the GI Tract variability, inactivation of some drugs by gastric acid and digestive enzymes, possible nausea and vomiting from local irritation, patient must be conscious and cooperative, because of ease, convenience, and relative safety oral administration is generally preferred to parenteral administration however parental may be superior dependent on the situation

Depot preparation

IM med that slowly absorb over a period of time ex. depot shot

IV barriers to absorption

None

Parenteral

anything OUTSIDE the GI tract by injection

Enteral

anything that goes through the GI tract

IV disadvantages

high cost, difficulty, inconvenience, irreversibility, fluid overload, infection, and embolism

IM disadvantages

possible discomfort, inconvenient, longer than IV, potential for injury; cannot be used for patients on anticoagulants (prevent blood from forming clots), volume restriction, breaking skin integrity.

Embolism

risk of having a blood vessel blockage at a site distant from the point of administration (bucket of air) form by air in the IV