Pharmacology for Collaborative Practice Foundational Concepts

The Basics of Pharmacology

• Pharmacology: study of drugs that alter functions of living organisms.

• Drugs are chemicals that are introduced into the body to cause some sort of biological change.

• Health care providers focus on how chemicals act on living organisms.

• Pharmacotherapy is the use of drugs to prevent, diagnose, or treat signs & symptoms and disease processes.

• Medications are drugs given for therapeutic purposes.

• Some drug effects are therapeutic, or helpful, but others are undesirable or potentially dangerous (adverse effects).

• Nurses deal with pharmacotherapeutics or clinical pharmacology.

Sources of Drugs

• Natural sources

  • plants

  • animal products

  • inorganic compounds

• synthetic sources

Natural Sources - Plants

• Synthetic version of the active chemical found in a plant

• Main component of the growing alternative therapy movement

Natural Sources - animal products

• Used to replace human chemicals that are not produced because of disease or genetic problems

• Genetic engineering

• Many of these preparations are now created synthetically

Natural Sources - inorganic compounds

Salts of various elements can have therapeutic effects in the human body (examples: ferrous sulfate, lithium drugs)

Synthetic Sources

• Genetic engineering alter bacteria to produce chemicals that are therapeutic and effective

• Original prototypes

The Responsibility of the Nurse

• Administering medications following the “three-checks of medications and the “10 rights of medication administration” consistently

• Assessing drug effects – side effects versus adverse drug reactions

• Intervening to make the drug regimen more tolerable

• Providing patient teachings about drugs and the drug regimen

• Monitoring the overall patient care plan to prevent medication errors

drug classifications

• Classified according to effects on

  • Specific body systems

    • Morphine works on CNS

  • Therapeutic uses

    • Antipyretics, antidepressants, antihypertensives

  • Chemical characteristics

    • benzodiazepines

drug prototypes

• Individual drugs that represent groups of drugs

  • Often the first drug of a particular group to be developed

  • Sets the standard for comparison

  • Morphine (represents opioid analgesics)

  • Penicillin (represents beta-lactam antibacterial drugs)

drug names

• generic neames

• trade / brand names

• orphan drugs

• May be prescribed and dispensed by either name

• You MUST learn by generic and recognize Trade name

Generic name (official name)

• Chemicals that are produced by companies involved solely in the manufacturing of drugs

• Bioavailability of the drug

• “Dispensed as written”

Orphan drugs

• Drugs that have been discovered, but are not financially viable and therefore have not been “adopted” by any drug company

  • The Orphan Drug Act of 1983

  • Companies get tax discounts for producing

Prescription drugs

Written by a licensed health care provider, such as a physician, dentist, or nurse practitioner

Over-the-counter (OTC) drugs - 2 bullet points

• do not require prescription

• Regulated by various laws

Local effects

act mainly at the site of application

systemic effects

taken into the body, circulated via the bloodstream to sites of action, and eventually eliminated from the body

Over-the-Counter Drugs

• Products that are available without prescription for self-treatment of a variety of complaints.

  • Some of these agents were approved as prescription drugs.

  • Later were found to be very safe and useful for patients (example: loratidine).

  • Many of these drugs were “grandfathered.”

• Nurses should consider several problems related to OTC drug use:

  • Taking these drugs could mask the signs and symptoms of underlying disease, making diagnosis difficult.

  • Taking these drugs with prescription medications could result in drug interactions and interfere with drug therapy.

  • Not taking these drugs as directed could result in serious overdoses.

Comprehensive Drug Abuse Prevention and Control Act

• The Controlled Substances Act of 1970

  • Control over the coding of drugs and the enforcement of these codes to the FDA and the Drug Enforcement Agency (DEA), a part of the U.S. Department of Justice.

• Prescription, distribution, storage, and use of these drugs are closely monitored.

• Local policies and procedures might be even more rigorous.

• Title II: Controlled Substances Act

  • Regulates manufacturing and distribution of

    • Narcotics, depressants

    • Stimulants, hallucinogens

    • Anabolic steroids

Drug Enforcement Administration (DEA)

• Enforces Controlled Substances Act

• Registers individuals and companies legally empowered to handle controlled substances

• Regulates documentation and handling of controlled substances

• Requires witness for disposal of controlled substances

Categories of Controlled Substances

• Schedule I – no accepted medical use – LSD, ecstasy

• Schedule II – medical use but high abuse potential – opioids, CNS stimulants, barbiturates, sedatives, hypnotics

• Schedule III – drugs with less potential for abuse – androgens, anabolic steroids, some depressants, mixtures with small amounts of controlled substances

• Schedule IV – drugs with some potential for abuse – benzodiazepines, sedative-hypnotics, appetite suppressants (phentermine)

• Schedule V – cough suppressants and antidiarrheal medications

Schedule I

no accepted medical use – LSD, ecstasy

Schedule II

medical use but high abuse potential – opioids, CNS stimulants, barbiturates, sedatives, hypnotics

Schedule III

drugs with less potential for abuse – androgens, anabolic steroids, some depressants, mixtures with small amounts of controlled substances

Schedule IV

drugs with some potential for abuse – benzodiazepines, sedative-hypnotics, appetite suppressants (phentermine)

Schedule V

cough suppressants and antidiarrheal medications

U.S. Food and Drug Administration (FDA)

• Responsible for ensuring safety and efficacy of drugs before they can be marketed.

• Since 1962, specific testing standards must be applied.

• Several phases of testing.

• Approves many new drugs annually

  • Both prescription and OTC

• May change status from prescription to OTC

  • Potential advantages and disadvantages

FDA Studies – Drug Evaluation

• Preclinical Trials

  • Chemicals tested on laboratory animals

• Phase I Studies

  • Chemicals tested on human volunteers

• Phase II Studies

  • Drug tried on informed patients with the disease

• Phase III Studies

  • Drug used in vast clinical market

• Phase IV Studies

  • Continual evaluation of the drug

Preclinical Trials

Chemicals tested on laboratory animals

Phase I Studies

Chemicals tested on human volunteers

Phase II Studies

Drug tried on informed patients with the disease

Phase III Studies

Drug used in vast clinical market

Phase IV Studies

Continual evaluation of the drug

Medication Administration orgs

• Quality and Safety Education for Nurses (QSEN)

• National Patient Safety Goals

• The Institute for Safe Medication Practices (ISMP)

Cells

• Are dynamic “factories” that deliver products to the appropriate destination within the body

• Differ from one tissue to another

• Exchange materials with immediate environment

• Obtain energy from nutrients

• Reproduce

• Communicate with one another via biologic chemicals

Drug Transport through Cell Membranes

• Drugs must reach and interact with cell membrane to affect cellular function.

• Most drugs are given for systemic effect.

• Transport pathways and mechanisms move drug molecules through the body.

Pharmacodynamics

• the science of dealing with interactions between living organisms and foreign chemicals.

• Each living system has chemical reactions occurring continuously in the body.

• When other chemicals (drugs) are added to the body other effects occur.

Pharmacokinetics

• The study of absorption, distribution, metabolism (biotransformation), and excretion of drugs

  • Onset of drug action

  • Drug half-life

  • Timing of the peak effect

  • Duration of drug effects

  • Metabolism or biotransformation of the drug

  • Site of excretion

Critical Concentration

The amount of a drug that is needed to cause a therapeutic effect

Loading Dose

a higher dose than that usually used for treatment

Dynamic Equilibrium

The actual concentration that a drug reaches in the body

• absorption

• distribution

• biotransformation

• excretion

Absorption

• Onset of drug action is determined by the rate of absorption.

• Factors that affect rate and extent of drug absorption

  • Dosage form, route of administration

  • Administration site blood flow, GI function

  • The presence of food or other drugs

Distribution

• Drugs are carried by blood and tissue fluids to

  • Action sites

  • Metabolism sites

  • Excretion sites

• Depends on adequacy of blood circulation

• Distribution process affected by

  • Protein binding

  • Blood–brain barrier

  • Pregnancy

  • Lactation

Metabolism

• the method by which drugs are inactivated or biotransformed by the body

• Drugs changed to

  • Inactive metabolites

  • Active metabolites

  • Prodrugs

• Drug-metabolizing enzymes are located within

  • Kidneys

  • Liver

  • Red blood cells, plasma

  • Lungs

  • Gastrointestinal mucosa

• Factors that affect drug metabolism

  • Enzyme induction

  • Enzyme inhibition

Excretion

• elimination of a medication from the body

• Requires adequate function of

  • Circulatory system

  • Kidneys

  • Bowels

  • Lungs

  • Skin

Half-Life

• is the time it takes for the amount of drug in the body to decrease to one-half the peak level.

• is affected by absorption, distribution, metabolism, and excretion.

Serum Drug Level

• a laboratory measurement of the amount of a drug in the blood at a particular time

• Reflects

  • Dosage, absorption

  • Bioavailability, half-life

  • Rates of metabolism, excretion

• Minimum effective concentration (MEC) must be present for efficacy.

Toxic concentration

• excessive level of medication in bloodstream; caused by

  • Single large dose

  • Repeated small doses

  • Slow metabolism of medication

Receptor Theory of Drug Action

• Drugs exert their effects by chemically binding with receptor cells through

  • Activation, inactivation, or alteration of intracellular enzymes

  • Changes in the permeability of cell membranes to one or more ions

  • Modification of the synthesis, release, or inactivation of neurohormones

Nonreceptor Drug Actions

• Relatively few drugs do not act on receptor sites. These few drugs include

  • Antacids

  • Osmotic diuretics

  • Several anticancer drugs

  • Metal chelating agents

Drug-Related Variables

• Dosage

  • Frequency, size, number of doses

    • Loading dose versus maintenance dose

• Route of administration

  • Influences absorption and distribution

    • PO versus IV

• Interactions that can increase therapeutic or adverse effects include

  • Additive effects – alcohol & sedative drugs

  • Synergism – acetaminophen & codeine

  • Interference – cimetidine & CV drugs

  • Displacement – aspirin displaces warfarin

• Drug–diet interactions - MAO inhibitor & tyramine containing foods

• Drug–drug interactions – antibiotics and BCP

Drug-to-Drug Interactions

• Can occur any time two or more drugs are taken together.

• Can occur at:

  • Site of absorption – prevent or accelerate absorption (e.g., Tetracycline with Calcium)

  • During distribution – competes for protein binding site (e.g., ASA & methotrexate so methotrexate bumped off sites so more is present in the blood rather than the targeted site so leads to toxicity)

  • During biotransformation – one drug stimulates of block the metabolism of the other drug. Warfarin metabolized faster if given with rifampin or barbiturates – so more inactive quicker and higher doses will be needed to reach therapeutic effect)

  • During excretion – one drug competes with other for excretion, leading to accumulation and toxic effects of one drug (e.g., digoxin and quinidine)

  • At the site of action – one drug may be an antagonist of the other drug or may cause effects that oppose those of the other drug – so does not cause therapeutic effect. (e.g., antihypertensive drugs and anti-allergy drugs)

Interactions in which drug effects are decreased include

• Antidote medication – antagonize the toxic effect

  • Naloxone for morphine sulfate

• Decreased intestinal absorption of drugs

  • Drugs containing aluminum, calcium or magnesium bind with oral tetracycline

• Increased metabolism rate of drugs

  • Phenytoin or rifampin with cigarette smoking

Drug-Food Interactions

• Certain foods interact with drugs, this also includes herbs and dietary supplements

• In most cases, drugs are best taken on an empty stomach. The golden rule is take medications 1 hour before food or two hours after food unless otherwise instructed.

Drug-Laboratory Test Interactions

• Drugs may alter the results of lab testing (e.g., Fragmin alters liver tests results)

• Laboratory test may be used to monitor the effects of other medications.

Herbal/Dietary Supplement Concerns

• Questionable safety due to unknown effect on humans, non-standardized ingredients.

• Use of supplements may keep the patient from seeking medical care.

• Supplements may interact with prescription medications to decrease therapeutic effect or increase adverse effects.

• Use of supplements not communicated to the health care provider.

Alternative Therapies and Herbal Medicine

• The active ingredient has not been tested by the FDA

• Incidental ingredients are unknown

• Patients do not always mention these therapies to their health care providers

• Drug–alternative therapy interactions may occur

• Herbal medications of alternative therapies are not controlled or tested by the FDA.

• Advertisement for these drugs is not restricted because they are considered dietary supplements.

• No regulation by any industry.

OTC Medications/Issues that can arise

• Can mask the signs and symptoms of disease

• Can interact with prescription drugs

• Can be taken in greater than the recommended dose, leading to toxicity

  • Acetaminophen

• Drugs that were “grandfathered in”

• Former prescription drugs that have been tested and found to be safe for use by the general public if used as directed

Off-Label Medications

• Definition

  • The use of a drug for an indication not approved by the FDA

• Occurrence

  • Commonly done for groups of patients for which there is little premarketing testing

  • Used with pediatric and geriatric population

Patient-Related Variable Influencing Drug Effects (age, weight, ethnicity, gender)

• Age – must understand lifespan considerations

• Body Weight – dose/kg

• Ethnicity – important differences you must understand

  • Asians usually need smaller doses especially beta-adrenergic blockers & several psychotropic drugs.

  • Caucasians with HTN do well on ACE inhibitors and Beta-blockers yet African Americans with HTN do better with Calcium channel blockers and diuretics

• Gender

  • Women have more fat, less muscle, less GFR and less hepatic enzyme activity – need smaller doses

  • Women respond better to SSRIs and TCAs, Women experience more pain relief from opioids

  • Men respond better to anti-anxiety meds; Men experience better pain relief from non-opioids than women

Patient-Related Variable Influencing Drug Effects (genetics, factors, tolerance)

• Pharmacogenetics – variations in drug response related to (r/t) genetics

  • People with G6PDH deficiencies develop hemolytic anemia when given anti-malarial drugs, sulfonamides, analgesics, antipyretics and other medications

• Physiological Factors – acid-base, electrolytes

• Pathological Factors – GI disorders, vascular disorders (distribution), liver (biotransformation), and kidney disorders (excretion) – see next slide

• Psychological Factors – positive attitude, trust, placebo effect

• Immunological Factors – allergies

• Drug Tolerance and Cross-tolerance

  • Tolerance especially in opioid analgesics if chronic use or ETOH use of opioids, alcohol and CNS depressants

  • Cross-tolerance if normally consume large amount or alcohol will need higher doses of general anesthesia or sedatives

Patient-Related Variable Influencing Drug Effects - factors

• Environmental Factors

• Cognitive Factors

• Sensory Factors

• Financial Factors

Adverse Effects of Drugs

• any undesired responses to medication administration

  • All drugs can produce adverse effects.

  • Can occur with usual therapeutic dosing.

  • More likely to occur or be more severe with high dosing.

  • Especially likely to occur with specific drugs and in older adults who take multiple drugs.

Adverse Drug Reaction

• Undesired effects that may be unpleasant or even dangerous

• Reasons Adverse Drug Reactions Occur

  • The drug may have other effects on the body besides the therapeutic effect.

  • The patient is sensitive to the drug being given.

  • The drug’s action on the body causes other responses that are undesired or unpleasant.

  • The patient is taking too much or too little of the drug.

Types of Adverse Reactions

• Primary Actions

  • Overdose; extension of the desired effect

  • Examples: Antihypertensive drug causing dizziness; Anticoagulant causing bleeding

• Secondary Actions

  • Undesired effects produced in addition to the pharmacologic effect

  • Examples: Antihistamines causing drowsiness; Antibiotics causing nausea and vomiting

• Hypersensitivity Reactions

  • Excessive response to primary or secondary effect of drug

  • Examples: Narcotics in elderly may cause increased stimulation and hyperactivity

Nurse’s Role

• Constantly be alerts for signs of drug reactions

• Teach patients and family members to look for signs of adverse drug reactions (AE)

• Implement specific comfort measures or precautions to prevent or help patient cope with AEs

• Assess for contraindication/cautions to increase patient safety and improve patient compliance with drug regimen

• Establish baseline assessment

• Monitor for signs and symptoms of AE

• Teach about drug interactions

• Teach patient/family about anticipated AE and comfort measures to cope with AE

• Intervene appropriately to AEs

Dermatological Reactions - rash / hives

• Assessment

  • Abnormalities in the skin, red area, blisters

• Interventions

  • May need to discontinue the medication in severe cases such as Stevens-Johnson Syndrome

  • Provide frequent skin care

  • Instruct patient to avoid rubbing, wearing tight or rough clothing; using harsh soaps or perfumed lotions or products

  • Administer antihistamines, as appropriate

  • May need to administer corticosteroids or/and emollients

Dermatological Reactions - stomatitis

• Assessment

  • Inflammation of the mucous membranes, gingivitis and glossitis

• Interventions

  • Frequent mouth care with nonirritating solution (AVOID alcohol products)

  • Small frequent meals

  • Refer to dentist

  • Antifungal agents and/or local anesthetics may be needed

Drug-Induced Tissue and Organ Damage - superinfections

• Destruction of the body’s normal flora, most frequently due to antibiotics

• Assessment

  • Fever, diarrhea, vaginal discharge, black or hairy tongue, glossitis

• Interventions

  • Supportive care (mouth and skin care), administer antifungal medications as needed, may also need to stop drug responsible for the superinfection

Drug-Induced Tissue and Organ Damage - blood dyscrasia

• Bone marrow suppression, most frequently due to antibiotics or antineoplastic agents

• Assessment

  • Fever, chills, weakness, sore throat, back pain, dark urine, decreased hematocrit (anemia), decreased platelets (thrombocytopenia), all cell counts are decreased on CBC (pancytopenia)

• Interventions

  • Monitor blood counts, protective isolation

  • Implement supportive measures (rest, injury protection)

Poisoning

• Poisoning occurs when an overdose of a drug damages multiple body systems.

• Damage to multiple systems can lead to a fatal reaction.

• Treatment varies accordingly with drug.

• Learn about antidotes or treatments for poisonings as we learn about the different drug classifications.

• Nurses must know the poison control number.

Altered Glucose Metabolism - hypoglycemia

• Examples: glipizide, glyburide

• Assessment Finding: Low serum blood glucose level < 50

  • Clinical manifestations include drowsiness, hunger, anxiety, headache, cold, clammy skin, shaking, fatigue, tachycardia, hypertension, numbness and tingling of mouth, tongue and/or lips, confusion, rapid shallow respirations

• Intervention: Restore glucose to the body

Altered Glucose Metabolism - hyperglycemia

• Example: ephedrine

• Assessment Finding: High serum glucose level > 200

  • Clinical manifestations include Polyuria (increased urination); Polydipsia (increased thirst), Polyphagia (increased hunger), deep respirations (Kussmaul respirations); hot flushed skin, fruity breath; nausea; fatigue

• Intervention: Administer medications (insulin) to decrease glucose level

Electrolyte Imbalance - hypokalemia

• Example: Loop diuretics like furosemide

• Assessment Finding: Decrease in serum potassium levels < 3.5 mEq/L

  • Clinical manifestations include muscle weakness, numbness and tingling in extremities, muscle cramps, n/v, diarrhea, irregular pulse, weak pulse, orthostatic hypotension, disorientation

• Interventions: Replace serum potassium (IV or oral supplement) and monitor serum levels of potassium

Electrolyte Imbalance - hyperkalemia

• Assessment Finding: Increase in serum potassium level > 5.0 mEq/L

  • Clinical manifestations include muscle weakness, muscle cramps, diarrhea, numbness and tingling, slow heart rate, low blood pressure, decreased urine output and difficulty breathing.

• Interventions: Decrease the serum potassium concentration (Sodium Polystyrene Sulfonate), monitor serum levels of potassium, and monitor cardiac rhythm

Sensory Effects - ocular toxicity

• Example: chloroquine

• Assessment Findings: Visual changes

  • Clinical manifestations –blurring of vison, color vision changes

• Interventions: Monitor for any visual changes when giving any medication that is known to cause ocular damage; discontinue medication as appropriate.

Sensory Effects - Auditory Damage

• Examples: ASA, macrolide antibiotics, streptomycin

• Assessment Findings: Dizziness, ringing in the ears (tinnitus), loss of balance, and loss of hearing

  • Clinical manifestations – falls, inability to hear

• Interventions: Monitor for hearing loss; discontinue medication as appropriate if a decrease in hearing is noted on assessment

Neurological Effects - General Central Nervous System (CNS) Effects

• Example: Beta-blockers

• Assessment Findings: Altered level of consciousness

  • Clinical manifestations – confusion, delirium, insomnia, drowsiness, hyper or hypo-reflexia, bizarre dreams, hallucinations, numbness & tingling and paresthesias.

• Interventions: Prevent injury, discontinue or decrease dose of drug as ordered

Neurological Effects - Atropine-like (Anticholinergic) Effects

• Examples: Atropine, antihistamines, cold remedies

• Assessment Findings: Dry mouth, urinary retention, blurred vision

  • Clinical manifestations – heart burn, altered taste perceptions, photophobia, headache, nasal congestion, palpitation, tachycardia

• Interventions: Sugarless lozenges to keep mouth moist; have the patient void before administration of the medication; teach patients to avoid hot environments, and prevent dehydration

Neurological Effects - Parkinson-like Syndrome

• Examples: antipsychotic and neuroleptic drugs

• Assessment Findings: Muscle tremors and changes in gait

  • Clinical manifestations – akinesia, drooling, rigidity, akathisia, dyskinesia

• Interventions: Discontinue medication as appropriate, teach patient to take small frequent meals if having difficulty swallowing

Neurological Effects - Neuroleptic Malignant Syndrome/Malignant Hyperthermia

• Example: Antipsychotic medications/general anesthesia

• Assessment Findings: Extrapyramidal symptoms

  • Clinical manifestations – extremely high fever, slowed reflexes, rigidity, HTN, tachycardia

• Interventions: Discontinue medication as appropriate; lower body temperature, institute safety precautions, administer ____________

Teratogenicity

Any drug that causes harm to the developing fetus or embryo

Teaching to prevent teratogenicity

• Advise the pregnant woman that any medication may have possible effects on the baby.

• Weigh the actual benefits against the potential risks.

• Discuss with pregnant women that they should not take medications without checking with their health care provider first.

• Patients must be taught to use two methods of contraception.

Toxicity - liver

• Assessment

  • Fever, nausea, jaundice, change in color of urine or stool, elevated liver enzymes

• Interventions

  • Discontinue medication

Toxicity - kidney

• Assessment

  • Change in urinary pattern, elevated BUN and creatinine

  • Gentamicin is very nephrotoxic

• Intervention

  • Notify physician, may need to stop medication or decrease the dosage

Toxicology: Drug Overdose

• Results from excessive amounts of medication

• May damage body tissues

• Common problem in both adult and pediatric populations

• May result from

  • Single large dose

  • Prolonged ingestion of smaller doses

• May involve alcohol, prescription, OTC, or illicit drugs

• Can be a medical emergency, regardless of location

Toxicology: Drug Overdose - main goal of tx

• Starting treatment soon after ingestion

• Supporting and stabilizing vital function

• Preventing further damage by

  • Reducing absorption

  • Increasing elimination

  • Administering antidotes whenever possible