MODULE 10 Pharmacology II
Lifespan Considerations • Pregnant Women • If possible, drug therapy should be delayed until after the first trimester, especially when there is danger of drug-induced developmental defects. • Potential fetal risks must be compared to maternal benefits when drug therapy is required. • Minimum therapeutic dose should be used for as short a time period as possible.
Lifespan Considerations (cont’d) • Pregnant Women • FDA Pregnancy Categories: • Drugs in categories A and B most likely carry little or no risk to the fetus. • Drugs in categories C and D most likely carry some risk to the fetus. • Drugs in category X are contraindicated during pregnancy.
Lifespan Considerations (cont’d) • Pregnant Women • There are certain situations that require judicious use of drugs during pregnancy: • Hypertension • Epilepsy • Diabetes • Infections that could seriously endanger the mother and fetus
Lifespan Considerations (cont’d) • Breast-feeding Women • Many drugs cross from the mother’s circulation into breast milk and subsequently to the infant, although in small amounts because this is not the primary excretion route. • Again, the risk to benefit ratio must be evaluated.
Lifespan Considerations (cont’d) • Children • Parent is important source of: • Information about the child • Source of comfort for the child • Partner with the health care team during drug therapy. • Should not be used to refer to a patient under 1 year of age.
Lifespan Considerations (cont’d) • Children • Differences in Physiology and Pharmacokinetics • Immaturity of organs most responsible • Anatomic structures and physiologic systems and functions are still in the process of developing
Lifespan Considerations (cont’d) • Children • Pharmacodynamics (Drug Actions) • Some drugs may be more toxic in children and some less. • More toxic– Phenobarbital, morphine, ASA • Same – Atropine, codeine, digoxin • Contraindicated–tetracycline (discolor teeth), corticosteroids (may suppress growth) Fluoroquinolone antibiotics (may damage cartilage leading to gait deformities) • Some tissues may be more sensitive – smaller doses
Lifespan Considerations (cont’d) • Children - Kid Facts • Safe, appropriate drug therapy must reflect the differences between adults and children. • The child’s stage of growth and development must be considered when assessing core patient variables and the interaction of core drug knowledge and core patient variables. • Pediatric drug dosages must be accurate to reduce risk of adverse effects and prevent over dosage.
Lifespan Considerations (cont’d) • Children - Drug Administration • Choice of appropriate route and/or site of drug administration will vary by the child’s age and size and the drug. • Special techniques may be needed to minimize traumatic effects to the child: • EMLA cream can be used to numb an area prior to an injection. • A popsicle or ice chips can be used to numb taste buds before unpleasant-tasting oral drugs. • Do not mix drug therapy into infant formula.
Lifespan Considerations (cont’d) • Children – Nursing Responsiblities • Education about medications should be provided for the patient, at an appropriate developmental level, and to the family. • Implement the “6 Rights.” • It may often be necessary for 2 nurses to check the medication(s). Check agency policy.
Lifespan Considerations (cont’d) • Older adults/Geriatric Considerations • Share common age-related changes and risk factors that alter drug administration, dosage and expected response to drug therapy. • All pharmacokinetic processes are altered, placing older adults at higher risk for adverse drug effects.
Lifespan Considerations (cont’d) • Geriatric Considerations Pharmacokinetics: • Alterations in absorption are more likely caused by disease processes. • Distribution is altered because of: • Decreased body mass • Reduced levels of plasma albumin • Less effective blood-brain barrier • Hepatic metabolism is slowed. • Renal efficiency is decreased: • Serum creatinine levels will remain normal even though kidney function is impaired.
Lifespan Considerations (cont’d) • Geriatric Considerations-Pharmacodynamic Changes • Receptor site changes. • Blood-brain barrier allows more drug to enter the brain. • Normal aging-related decline in organ or system function occurs.
Lifespan Considerations (cont’d) Geriatric Considerations • Polypharmacy • May see multiple MDs for various illnesses and all may prescribe meds. • Consume approx 32% of all Rx drugs and 40% over the counter (OTC) drugs • Most common Prescriptions – antihypertensives, insulin, beta blockers, digitalis, diuretics, potassium (K) supplements • Most common OTC’s – analgesics, laxatives, nonsteroidal anti-inflammatory drugs (NSAIDS)
Lifespan Considerations (cont’d) Geriatric Considerations • Nonadherence– Lack of knowledge or incomplete knowledge leads to misunderstanding about medication regime. • Lifestyle – Choices may have to be made between food, rent and purchase of medications.
Lifespan Considerations (cont’d) • Geriatric Considerations: • Simplify the therapeutic regimen. • Give memory aids (if necessary). • Give written instructions. • Determine financial access to drug therapies. • Assess cultural barriers. • Titrate the dose upward slowly to minimize adverse effects.
Cultural Considerations in Drug Therapy • The Law of Cultural Diversity • Each patient needs to be considered an individual, regardless of cultural, ethnic or religious beliefs. • Although members of a culture share certain beliefs and practices, individual variation will still occur. Many cultural groups in the U. S. have beliefs that reflect both their original ethnic culture and the dominant culture of the United States.
Ethnic Considerations in Drug Therapy • Drug polymorphism • Critical in understanding a patient’s response to drug therapy • May explain many adverse and idiosyncratic reactions • Refers to how individuals metabolize differently • Looks at genetics that often have a common basis in ethnic background • Opens up a new field of study in pharmacology that has been lacking for years due to societal factors • Examples: Why does the African-American respond differently to antihypertensives, the Chinese patient require lower doses of benzodiazepines, the Caucasian respond differently to some pain medications?
Ethics and Drug Therapy Nurse’s responsibility is to always be a patient advocate and remain nonjudgmental. • ANA Code of Ethics • Canadian Nurses Association Code of Ethics • Various Nurse Practice Acts • All share the framework for the professional practice of nursing. • All believe that, professionally, the nurse provides safe nursing care to patients regardless of the group, community, ethnicity or culture. • Nursing does not impose values or standards on the patient. • Nurses assist the patient and family in facing decisions regarding health care.
Botanical Dietary Supplements • For a complete list of botanical dietary supplements fact sheets, (National Institutes of Health), see : http://www.ods.od.nih.gov/Health_Information/Botanical_Supplements.aspx
The 5th Vital Sign Pain Opioid & Non-Opioid Analgesics Aspirin NSAIDs COX-2 inhibitor Acetaminophen Narcotics
Analgesics Definition of an analgesic: • “Medications that relieve pain without causing loss of consciousness” • Pain is a subjective experience. The nurse must believe the patient. PET scans now can visualize brain’s responses to many kinds of pain.
Proposed Pain Pathway Nociceptors (free nerve endings) Afferent stimulation of sensory “A” or “C”fibers Release of peptide substance P from unmylinated “C” fibers in dorsal horn Dorsal horn spinal cord – the location of the “gate” 3 major brain pathways: Spinothalamic, spinoreticular, spinomesencephalic (Multiple neurotransmitters released)
Pathophysiological Many theories of pain transmission are not completely understood. • Nociceptive pain • Neuropathic pain • Psychogenic pain The type of pain determines the analgesic. Neuropathic pain is often treated with anticonvulsants, tricyclic antidepressants added onto narcotics
Pain Transmission These techniques also allow some non- pharmacological relief from pain: • Massage • Deep pressure • Distraction • Relaxation • Vibration Can be used as independent nursing intervention after assessment The above activate the large “A” fibers.
Factors Influencing Pain Perception • Type of pain • Acute vs. chronic • Visceral vs. cutaneous • Nociceptive, neuropathic, psychogenic • Intensity of pain & type of injury • Inflammatory process • Degree of Anxiety
Factors Influencing Pain Perception • Sensory input • Social support • Fatigue • Age, sex & culture • Memory & information processing • Level of consciousness • Type, amount, route of analgesic
Drugs Influencing Pain Perception • Narcotics (opioids) modify pain perception via Central Nervous System (CNS) & dorsal horn via binding to Mu, kappa & delta opioid receptors & inhibiting substance “P” and glutamate (an excitorary neurotransmitter). Alter perception of pain via opiate receptors, and alter psychological responses via brain. • Other mechanisms to alter pain involve effects on the Autonomic Nervous System (ANS), skeletal muscle response & diagnosis.
Drugs Influencing Pain Perception • Nonopiate analgesics (salicylates, NSAIDS, etc.) • Control pain impulses in the periphery • Often involving the Arachidonic acid pathway responsible for inflammation and an immune response
Some Pain Mysteries • Phantom pain • Referred pain • Pain experienced after cordectomy • Placebo response
Prostaglandins • Associated with inflammation • Involved in the temperature set point of the hypothalamus • Sensitize pain receptors to mechanical and chemical stimulation • Found in many cells and body processes
Leukotrines • Arachidonic acid metabolites • Mediators in inflammation • Synthesized when tissue injury occurs • May be involved in rheumatoid arthritis, asthma and system wide anaphylaxis • Bronchoconstrictor and vasodilator
Synthesis of Prostaglandins Arachidonic acid LipoxygenaseCyclooxygenase LeukotrinesProstaglandins enzymes
Cyclooxygenase TWO Enzyme FORMS CYCLOOXYGENASE-1 & CYLOOXYGENASE- 2 COX-1 COX-2 Prostaglandins Protects stomach lining Inflammation Pain
Peripheral control of pain Release of prostaglandin inflammation & pain Prostaglandins mediate pain and swelling by triggering vasodilatation. Prostaglandins are synthesized by the enzyme cyclooxygenase which breaks down arachidonic acid to synthesize prostaglandin. This is the basic method of action of aspirin and NSAIDs.
Inhibition of Cox-1 & Cox-2 • Inhibition of both Cox-1 & Cox-2 will be effective as an: • ANALGESIC • ANTIPYRETIC • ANTI-INFLAMMATORY AGENT • AGENT TO DECREASE PLATLET AGGREGATION • Also associated with stomach damage due to COX-1 inhibition
Aspirin • Inhibits both Cox-1 and Cox-2 • Is used as a analgesic • Is used as a anti-inflammatory agent • Is used as a antipyretic • But can cause stomach damage • Is used to prevent coronary heart disease (CHD) via platelet aggregation • In what other cases should aspirin NOT be used?
Aspirin adverse effects & interactions • Tinnitus – sign of toxicity • Dyspepsia • Highly protein bound so it displaces other medications: oral anticoagulants, oral hypoglycemics, some anticonvulsives. • G.I. Bleeding increased with glucocorticoids, alcohol • High doses may cause excessive bruising • Highly lethal if taken in overdose - No known antidote • Caution with asthmatic patients (may have aspirin allergy also)
Children under 15 withviral infection Reye’s syndrome is associated with aspirin use.
NSAIDSNon-Steroidal Anti-Inflammatory Drug • First line treatment for inflammation • Both COX-1 & COX-2 inhibitors • Mild to moderate pain of various types • Good for dysmenorrhea • Antipyretic • Reversibly inhibit platelet aggregation (less than aspirin because aspirin has irreversible inhibition) • INHIBIT THE PRODUCTION OF PROSTAGLANDINS THAT MEDIATE PAIN AND INFLAMMATION
Side effects & Interactions of NSAIDs • G.I. Bleeding, dyspepsia • Liver toxicity or renal damage with large doses, prolonged use • Highly bound to plasma protein so displace other medications, leading to exacerbation of their side effects These adverse effects can occur with oral or parenteral routes and even if enteric coated.
Don’t give aspirin or NSAIDs Patients with ulcers Patients going to surgery Patients with an allergy to aspirin Alcoholic patients When patient is nauseated or vomiting Patients on glucocorticoids (without M.D. order) Patients taking ACEIs (Angiotensin Converting Enzyme Inhibitors) Caution with NSAIDs in patients with CHF
Celecoxib (Celebrex)Approved for osteoarthritis and rheumatoid arthritis Acute pain & dysmenorrhea Do not give if sulfa allergy COX-2 INHIBITOR Only COX-2 inhibitor currently available Has anti-inflammatory properties
Acetaminophen (Tylenol) • Is a very weak inhibitor of both Cox-1 and Cox-2 • Is used as an antipyretic • Is used as an analgesic • Can not be used as an anti-inflammatory agent • Does not stop platelet aggregation • May work by inhibiting prostaglandin synthesis in the CNS
Acetaminophen • Is the drug of choice for mild to moderate pain • Is often combined with opioids to treat moderate to severe pain • Will cause liver failure in LARGE doses or prolonged use (2.4 to 4 grams/day) • Liver failure with alcohol due to metabolic pathways • Ceiling effect • Overdose is difficult to treat - use acetylcysteine
Acetaminophen • Young children, older adults, daily drinkers of 3 or more alcoholic beverages and those with kidney or liver disease are at risk for accidental acetaminophen poisoning • Acetaminophen found in many pharmaceuticals • Vicodin ES (5 tabs Q. D. = 4 gm) • Tylenol extra-strength (8 tabs = 4 gm) • What other OTC medications might contain acetaminophen?
Neuropathic Pain • Difficult to treat • Use of opioids does not completely control pain • Usually add on another medication from a different class (co-analgesic agents) • immipramine (Tofranil) Tricyclic antidepressant -TCA • gabapentin (Neurontin) Anticonvulsant • Duloxetine (Cymbalta) newest SNRI (serotonin norephinephrine reuptake inhibitor) - also used for depression • Effexor is another medication in this class • New pregabalin (Lyrica) anticonvulsant - alpha2 - delta ligand • + other medication classes
Opioids (Narcotic Analgesics) Natural, synthetic and semisynthetic ALL COMPARED TO MORPHINE