Ch11 ROUTES OF DRUG ADMINISTRATION Flashcards
most common route of administration?
enteric (the mouth or the rectum), whereby drugs enter the body via the gastrointestinal (GI) tract
parenteral drug administration
A route of drug administration that does not involve the GI tract
Oral
per os - by mouth
absorbed in the stomach or small intestine
usually have a delay/coating to facilitate absorption
sublingual
under the tongue - not enteric because they are absorbed through the mucosa
first pass alteration
PO drugs first pass through the liver where a large proportion is broken down before reaching the target organ
First-pass alteration is carried out by the intestinal epithelium and liver; thus, all substances given PO will be subjected to alteration
Rectal Administration
Drugs may be given rectally for either a local or systemic effect and are generally well absorbed through the rectal mucosa.
Rectal administration is most commonly used when an oral drug is inappropriate—for example, when someone is suffering from nausea and vomiting, or in babies and small children who cannot swallow oral medications.
less first pass alteration as the drug bypasses the liver
Solutions
A solution is a compound that is truly dissolved in a solvent
eg. An example of a drug that comes in a solution is the antibiotic erythromycin stearate (Erythromycin®).
Suspensions
A suspension is a solid dispersed in a liquid, like sand in water
Emulsions
An emulsion is a liquid dispersed in another liquid.
Solids
The solid drug particles can be enclosed in a gelatin capsule or in a moulded or compressed tablet form
Some tablets are scored to simplify giving half-tablet doses. If the tablet is not scored, it should not be divided, because the coating on the tablet will be disrupted. For example, some compressed tablets have an “enteric coating” that keeps the drug from dissolving in the stomach
Inhalational Administration
Inhalation can be a very effective means of getting a drug into the bloodstream because of the large and highly vascularized inner surface of the lungs
Pulmonary absorption of drugs will avoid first-pass metabolism.
Injections
Injecting a drug avoids the gastrointestinal barrier and first-pass metabolism
Intramuscular
an effective means for delivering large volumes of drugs that cannot be taken by mouth.
IM is slower than IV
Subcutaneous
Injecting a drug into the fatty subcutaneous tissue allows for a slower and more constant rate of absorption than IM injection affords
eg. Insulin
Intravenous
Via this route, drug absorption is immediate and all of the drug goes directly into the venous blood for distribution. Distribution is rapid, and the lack of first-pass
metabolism and other factors that interfere with drug availability are absent, so it is relatively easy to predict blood levels of the drug
