Comprehensive Pharmacology and Drug Therapy for Nursing Practice

Drug

any chemical that can affect living processes

Pharmacology

study of drugs and their interactions with living systems (animals, plants)

Pharmacotherapeutics

the use of drugs to diagnose, prevent, or treat disease or to prevent pregnancy

Brand Name

A drug sold by a drug company under a specific name or trademark and that is protected by a patent

Generic Name

a prescription drug that has the same active ingredients as the brand name

Effectiveness

ability of a drug to produce a desired effect - most important property a drug can have

Safety

drug can not produce harmful effects

Selectivity

drug produces only the response for which it is given

Therapeutic Effect

the desirable and intended outcome or response from a drug

Maximum Benefit with Minimal Harm

the ideal outcome for a response by having a maximum positive effect while minimizing any potential risks associated with that specific drug therapy

10 Rights of Medication Administration

Right drug, Right route, Right Patient, Right Dose, Right Time, Right Assessment, Right Documentation, Right Evaluation, Right of patient education, Right of patient to refuse care

Preclinical Testing

Testing for 1-5 yrs on animals before applying to FDA for human testing permissions

Clinical Testing

4 phases encompassing 2-10 yrs

Phase 1

healthy volunteers typically unless severe side effects as in cancer drugs etc. 3 goals: Evaluate drug metabolism, Pharmacokinetics, Biologic effects

Phases 2&3

Patients utilized to determine therapeutic effects, dosage range, safety, and effectiveness. 500-5000 pt's receive the drug and only a few hundred take it for more than 3-6 months

Phase 4

Postmarketing Surveillance - Drug is released for general use, permitting observation of its effects in a large population

FDAAA of 2007

increased effectiveness of postmarketing surveillance

Pharmacokinetics

the study of drug movement throughout the body

Pharmacodynamics

study of biochemical and physiological effects of drugs on the body and the molecular mechanisms by which those effects are produced

Absorption

Movement of drug from its site of administration into the blood.

Factors affecting Absorption

Rate of dissolution, Surface area, Blood flow, Lipid solubility, pH partitioning, Distribution, Metabolism.

Metabolism

How the body converts medication into a less, or more active form (these forms are also known as metabolites).

Liver

Most drug metabolism takes place in the liver.

Hepatic microsomal enzyme system

Also known as the p450 system, it performs drug metabolism.

First-pass effect

A drug that undergoes rapid hepatic metabolism is often administered parenterally.

Enterohepatic recirculation

Drugs can remain in the body much longer than they otherwise would.

Excretion

Drugs and their metabolites can exit the body in urine, bile, sweat, saliva, breast milk, and expired air.

Kidney

Most important organ for drug excretion.

Intravenous Administration

Advantages include Rapid Onset, Precise Control, Permits use of large fluid volumes, Permits use of irritant drugs.

Disadvantages of Intravenous Administration

High Cost, Difficulty, Inconvenience, Irreversibility.

Intramuscular and Subcutaneous Administration

Rate of absorption is determined by blood flow and drug solubility.

Advantages of Intramuscular and Subcutaneous Administration

No significant barriers (only barrier is capillary wall), Suitable for poorly soluble drugs and depot preparations.

Disadvantages of Intramuscular and Subcutaneous Administration

Discomfort, Inconvenience, Potential for injury.

Oral Administration

Barriers include a layer of epithelial cells and capillary wall.

Absorption Pattern in Oral Administration

Multiple factors affect absorption.

Advantages of Oral Administration

Easy and Convenient.

Plasma drug level

The minimum effective concentration (MEC) is defined as the plasma drug level below which therapeutic effects will not occur.

Toxic concentration

The plasma level at which toxic effects begin.

Therapeutic Range

Plasma drug levels falling between the MEC and the toxic concentration.

Narrow therapeutic range

Drugs that have a narrow therapeutic range are less safe.

Wide therapeutic range

Drugs that have a wide therapeutic range can be administered safely with relative ease.

Drug-receptors

Receptors are any functional macromolecule in a cell to which a drug binds to produce its effects.

Dose-response relationships

Relationship between the size of an administered dose and the intensity of the response produced.

Relative potency

The amount of drug we must give to elicit an effect.

Maximal efficacy

The largest effect that a drug can produce.

Interpatient variability

The dose required to produce a therapeutic response can vary substantially from patient to patient.

ED50

The dose that is required to produce a defined therapeutic response in 50% of the population.

LD50

The dose that is lethal to 50% of the animals treated.

Therapeutic index

A measure of a drug's safety.

Drug-drug interactions

Interactions that can occur from multiple drug ingestion, often when patients take a variety of drugs throughout the day.

Consequences of drug-drug interactions

Include intensification of therapeutic effects, reduction of therapeutic effects, and/or creation of a unique response.

Grapefruit juice effect

Inhibits metabolism of certain drugs, raising blood levels, but does not affect IV drugs.

MAOIs + tyramine

Can cause life-threatening hypertension.

Potassium sparing diuretics

Can have toxic effects when combined with salt substitutes.

Aluminum containing antacids

Can have toxic effects when combined with citrus beverages.

Timing of administration

Some drugs are better taken on an empty stomach, while others should be taken with food.

Drug-herb interactions

Conventional drugs can interact with herbal preparations, but reliable information is often lacking.

Pharmacokinetic interaction

Altered absorption, distribution, renal excretion, or metabolism of drugs.

Altered absorption

Can be caused by elevated gastric pH, laxatives, or drugs that depress peristalsis.

Altered distribution

Can occur due to competition for protein binding and alteration of extracellular fluid pH.

Altered renal excretion

Drugs can alter filtration, reabsorption, and active secretion.

Altered metabolism

Can increase the rate of metabolism 2-3 fold over 7-10 days.

Pharmacodynamic drug-drug interactions

Interactions that occur at the same receptor, often resulting in inhibitory effects.

Combined toxicity

Drugs with overlapping toxicities should not be used together.

Minimum drug concentration

The amount of drug at a minimum which will have efficacy.

Drug half-life

The time required for the amount of drug in the body to decrease by 50%.

Drug plateau

When there is a steady level of drugs in the body.

Potency

Refers to the amount of drug required to elicit an effect.

Agonists

Molecules that activate receptors.

Antagonists

Produce effects by preventing receptor activation by endogenous regulatory molecules and drugs.

Affinity

The attraction between a drug and its receptor.

Intrinsic activity

The ability of a drug to activate a receptor.

Side Effect

A nearly unavoidable secondary drug effect produced at therapeutic doses.

Adverse Effect

Unexpected effects, severe response!

Toxicity

The degree of harmful physiological effects caused by excessive drug dosing.

Allergic reaction

An immune response.

Synergistic effect

Two drugs given together have a greater impact than when given alone.

Idiosyncratic effect

An uncommon drug response resulting from a genetic predisposition.

Paradoxical effect

Opposite of the intended drug response.

Iatrogenic disease

Disease that occurs as the result of medical care or treatment. The term is also used to denote a disease produced by drugs.

Physical dependence

The body has adapted to drug exposure in such a way that an abstinence syndrome will result if drug use is discontinued.

Carcinogenic effect

The ability of certain medications and environmental chemicals to cause cancers.

Teratogenic effect

A drug-induced birth defect.

Types of Medication Errors

Wrong patient, Wrong drug, Wrong route, Wrong time, Wrong dose, Omitted dose, Wrong dosage form, Wrong diluent, Wrong strength/concentration, Wrong infusion rate, Wrong technique, Deteriorated drug error, Wrong duration of treatment.

Ways to Reduce Medication Errors

Institutional Culture, Infrastructure, Clinical Practice, Technology.

How to Report Medication Errors

MER program: nationwide system run by ISMP reporting done online or via phone and is confidential. All information gathered by MER program is forwarded to FDA, the ISMP, and the product manufacturer.

Individual variation

Factors affecting drug responses including body weight, composition, genetics, gender, race, age.

Body Weight and Composition

Body surface area versus weight.

Age

Significant variability with age; infants and older patients especially sensitive to drugs.

Pathophysiology

Includes Kidney Disease, Liver Disease, Acid-Base Imbalance, Altered Electrolyte Status.

Tolerance

When a patient becomes tolerant to a drug, the dosage must be increased to maintain beneficial effects.

Placebo Effect

A beneficial effect produced by a placebo treatment.

Variability in Absorption

Differences in how drugs are absorbed in individuals.

Genetics

Genetic factors that can influence drug response.

Gender- and Race-Related Variations

Differences in drug response based on gender and race.

Comorbidities and Drug Interaction

The presence of multiple conditions that can affect drug response.

Diet

Nutritional factors that can influence drug metabolism and response.

Failure to Take Medicine as Prescribed

Not adhering to the prescribed medication regimen.

Kidney Disease

Reduced excretion and increased toxicity.

Liver Disease

Reduced metabolism and increased toxicity.