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PHARMACOLOGY FOR NURSES

Dr. Ding Villanueva PharmD, MHA, RPh, RN Lecturer, Riverside College

INTRODUCTION

DISCLOSURE

Dr. Villanueva has no financial disclosure,

actual or potential conflict of interest in

relation to this presentation.

WHY STUDY PHARMACOLOGY

DOCTOR OF MEDICINE

MASTER OF SCIENCE IN PHYSICIAN ASSISTANT STUDIES

MASTER OF SCIENCE IN NURSING

BACHELOR OF SCIENCE IN PHARMACY

BACHELOR OF SCIENCE IN NURSING

BACHELOR OF SCIENCE IN PHYSICAL THERAPY

Pharmacology is the body of knowledge concerned with the

action of chemicals on biologic systems.

Medical pharmacology is the area of pharmacology

concerned with the use of chemicals in the prevention,

diagnosis, and treatment of disease, especially in humans.

Toxicology is the area of pharmacology concerned with the

undesirable effects of chemicals on biologic systems.

Pharmacokinetics describes the effects of the body on

drugs, eg, absorption, metabolism, excretion, etc.

Pharmacodynamics denotes the actions of the drug on the

body, such as mechanism of action and therapeutic and toxic

effects.

Pharmacokinetics refers to how medications travel through the body. They undergo a variety of biochemical processes that result in absorption, distribution, metabolism, and excretion.

Oral

BARRIERS TO ABSORPTION: Medications must pass through the

layer of epithelial cells that line the GI tract.

ABSORPTION PATTERN: Varies greatly due to:

● Stability and solubility of the medication

● GI pH and emptying time

● Presence of food in the stomach or intestines

● Other concurrent medications

● Forms of medications (enteric-coated pills, liquids)

Sublingual, buccal

BARRIERS TO ABSORPTION: Swallowing before dissolution

allows gastric pH to inactivate the medication.

ABSORPTION PATTERN: Quick absorption systemically

through highly vascular mucous membranes

Other mucous membranes (rectal, vaginal)

BARRIERS TO ABSORPTION: Presence of stool in the rectum

or infectious material in the vagina limits tissue contact.

ABSORPTION PATTERN: Easy absorption with both local and

systemic effects

Subcutaneous, intramuscular BARRIERS TO ABSORPTION: Capillary walls have large spaces between cells. Therefore, there is no significant barrier. ABSORPTION PATTERN ● (^) Solubility of the medication in water: Highly soluble medications have rapid absorption (10 to 30 min); poorly soluble medications have slow absorption. ● (^) Blood perfusion at the site of injection: sites with high blood perfusion have rapid absorption; sites with low blood perfusion have slow absorption.

Intravenous

BARRIERS TO ABSORPTION: No barriers

ABSORPTION PATTERN

● Immediate: enters directly into the blood

● Complete: reaches the blood in its entirety

METABOLISM

Metabolism (biotransformation) changes medications into less active

or inactive forms by the action of enzymes. This occurs primarily in

the liver, but it also takes place in the kidneys, lungs, intestines, and

blood.

FACTORS INFLUENCING THE RATE OF MEDICATION

METABOLISM

● Age: Infants have a limited medication-metabolizing capacity. The

aging process also can influence medication metabolism, but varies

with the individual. In general, hepatic medication metabolism tends

to decline with age. Older adults require smaller doses of medications

due to the possibility of accumulation in the body.

● Increase in some medication-metabolizing enzymes: This can metabolize a particular medication sooner, requiring an increase in dosage of that medication to maintain a therapeutic level. It can also cause an increase in the metabolism of other concurrent-use medications. ● First-pass effect: The liver inactivates some medications on their first pass through the liver, and thus they require a nonenteral route (sublingual, IV) because of their high first-pass effect. ● Similar metabolic pathways: When the same pathway metabolizes two medications, it can alter the metabolism of one or both of them. In this way, the rate of metabolism can decrease for one or both of the medications, leading to medication accumulation. ● Nutritional status: Clients who are malnourished can be deficient in the factors that are necessary to produce specific medication-metabolizing enzymes, thus impairing medication metabolism.