Pharmacology Concepts and Routes of Administration

Agonist

A medication that causes stimulation of receptors.

Antagonist

A medication that binds to a receptor and blocks other medications or chemicals from attaching.

Dose

The amount of the medication that is given, often depending on the patient's weight or age.

Action

The intended therapeutic effect that a medication is expected to have on the body.

Pharmacokinetics

The actions of the body upon the medication, including how it is absorbed, distributed, changed, or eliminated.

Onset of action

The time from medication administration until clinical effects occur.

Duration

The length of time that clinical effects persist.

Elimination

How medications or chemicals are removed from the body.

Peak

The point or period when the maximum clinical effect is achieved.

Indications

The reasons or conditions for which a particular medication is given.

Contraindications

Situations or conditions in which a medication should not be given because it would harm the patient or have no positive effect.

Absolute contraindication

A condition where a medication should never be given (e.g., severe hypotension for nitroglycerin).

Relative contraindication

A condition where the benefits of administering the drug may outweigh the risks (e.g., glaucoma for epinephrine during anaphylaxis).

Adverse effects

Any actions of a medication other than the desired ones.

Unintended effects

Adverse effects that are undesirable but pose little risk to the patient (e.g., a slight headache after taking nitroglycerin).

Untoward effects

Adverse effects that can be harmful to the patient (e.g., severe hypotension after taking nitroglycerin).

Generic name

A simple, clear, nonproprietary name for a medication that is not capitalized (e.g., ibuprofen).

Trade name

The brand name that a manufacturer gives to a medication, written with a capital letter (e.g., Tylenol).

Enteral medications

Medications that enter the body through the digestive system, typically absorbing slowly.

Parenteral medications

Medications that enter the body by a route other than the digestive tract, skin, or mucous membranes, typically absorbing quickly.

Absorption

The process by which medications travel through body tissues until they reach the bloodstream.

Polypharmacy

The use of multiple medications on a regular basis by a single patient, common among geriatric populations.

Per rectum (PR)

Through the rectum; rapid absorption, commonly used with children or unconscious patients.

Oral (Per os / PO)

By mouth; slow absorption, noninvasive, but unpredictable if the patient is vomiting or has diarrhea.

Intravenous (IV) injection

Into the vein; immediate absorption, the fastest way to deliver a chemical substance.

Intraosseous (IO) injection

Into the bone marrow; immediate absorption, requires drilling into the bone, used primarily for unconscious patients in cardiac arrest or extreme shock.

Subcutaneous injection

Under the skin into fatty tissue; slow absorption, providing longer-lasting effects (e.g., insulin).

Intramuscular (IM) injection

Into the muscle; moderate to rapid absorption due to high vascularity, typically delivered via auto-injector.

Inhalation

Breathed into the lungs; rapid absorption, targeting lung tissues directly to minimize systemic side effects.

Sublingual (SL)

Under the tongue; rapid absorption through oral mucosa within minutes, bypassing stomach acids.

Transcutaneous (Transdermal)

Through the skin; slow, continuous absorption for systemic, long-lasting effects via patches or pastes.

Intranasal (IN)

Into the nostril via a mucosal atomizer device (MAD); rapid absorption due to highly vascular mucous membranes.