Special Populations Pharmacology Review PDF

OBSTETRIC S SPECIAL PEDIATRICS POPULATIONS GERIATRIC S   Review the presentation Special Populations posted on Brightspace.  Read the following articles:  Medication and the elderly REQUIREMENT ...

OBSTETRIC S SPECIAL PEDIATRICS POPULATIONS GERIATRIC S   Review the presentation Special Populations posted on Brightspace.  Read the following articles:  Medication and the elderly REQUIREMENT  Drug-related illness in the elderly  Drug categories of concern in the elderly S  Changes in Drug Response in Pregnancy  Changes in Drug Response in Neonates and Infants  Watch the following videos:  Elderly and their medication (3:03)   Describe how the physiologic changes of pregnancy affect pharmacokinetics and pharmacodynamics.  Discuss the role of the placenta in drug transfer to the fetus.  Discuss medication risk labeling in pregnancy, lactation, and reproduction.  Describe how the physiology of neonates and OBJECTIVES pediatrics affects pharmacokinetics and pharmacodynamics.  Discuss special considerations in pediatric drug administration.  Describe how the physiologic changes associated with aging affect pharmacokinetics and pharmacodynamics.  Discuss special considerations in drug administration in the elderly. PREGNANCY PHARMACOKINETIC CHANGES Absorption GI: Decreased emptying, increased blood flow, increased pH. Cardiac output: blood flow to organs and tissues increases. IV/IM/SC absorption is increased. Distribution Plasma volume increases 30-50% leading to a decease in circulating levels of some drugs. Body fat increases giving lipophilic drugs a greater reservoir for distribution. Protein dilution decreases protein binding. PHARMACOKINETIC CHANGES Metabolism Pregnancy hormones can induce or inhibit metabolic enzymes (variable drug effect). Elimination Blood flow to the kidneys is increased leading to faster drug elimination. Tubular reabsorption increases. Hepatobiliary drug clearance is reduced. Renal clearance becomes difficult to predict. PHARMACODYNAMIC CHANGES Increased Changes to sensitivity Fetal drug to considerati therapeutic anaesthetic ons indices s TRANSFER TO THE FETUS  The placenta is a semipermeable membrane that can metabolize some drugs that pass through it.  Approximately 40-60% of umbilicus venous blood flow enters the fetal liver and undergoes first pass metabolism.  Drug characteristics that increase placental drug transfer:  Lipophilic  Small molecular size  Use of placental transporter  Low degree of protein binding PREGNANCY RISK CATEGORIZATION  Most information about drug safety during pregnancy is derived from animal studies, uncontrolled studies, and post-marketing surveillance. Consequently, the FDA classification system led to confusion and difficulty applying available information to clinical decisions. In December 2014, the FDA responded by requiring that the pregnancy categories A, B, C, D, and X be removed from the labeling of all drugs.  Instead of categories, the FDA now requires that labeling provide information about the specific drug for use in:  Pregnancy  Lactation  Females and males of reproductive potential  The information must provide a risk summary, clinical considerations, and available drug data. NEARPOD QUESTION 1 NEARPOD QUESTION 1  Discuss the various factors that affect your drug and dose choices in the following cases: 1. A man or woman that is trying to conceive a child. 2. A woman in her first trimester. 3. A woman in labor. PEDIATRICS PHARMACOKINETIC CHANGES  The primary difference in pharmacokinetics in pediatrics is the change in body composition with age.  Lower muscle mass, lower body fat, lower plasma protein content, and greater total body water all affect drug distribution and storage.  The blood-brain barrier is more permeable which allows more drug to cross into the brain. PHARMACOKINETIC CHANGES Absorption GI: Delayed emptying (neonate), increased pH, delayed intestinal absorption (infant) Skin: Thin stratum corneum leads to increased absorption Variable IM absorption rates due to poor muscle mass, decreased movement, increased capillary network Respiratory: High minute ventilation but low tidal volumes and flow rates leads to increased absorption of gases but decreased absorption of aerosoles. Distribution Greater for water-soluble drugs, lower for lipid-soluble drugs, decreased protein binding. Immature blood brain barrier increases CNS distribution. METABOLISM  Drug metabolism and elimination vary with age and depend on the substrate or drug, but most drugs, and most notably phenytoin, barbiturates, analgesics, and cardiac glycosides, have plasma half-lives 2 to 3 times longer in neonates than in adults.  Phase I metabolism activity is reduced in neonates, increases progressively during the first 6 months of life, exceeds adult rates by the first few years for some drugs, slows during adolescence, and usually attains adult rates by late puberty.  Drug metabolites are eliminated primarily through bile or the kidneys. Renal elimination depends on plasma protein binding, renal blood flow, glomerular filtration rate, and tubular secretion. All of these factors are altered in the first 2 years of life. PHARMACOKINETIC CHANGES Elimination Decreased GFR (infant) leading to reduced elimination. Decreased tubular secretion leading to decreased elimination. PHARMACODYNAMIC CHANGES Limited cardiovasc Vulnerable Respiratory Hypoglyce ular to CNS immaturity mia risk compensati depression on NEARPOD QUESTION 2 NEARPOD QUESTION 2  Discuss how the ages of the following patients might affect your choice of drug, dose, and dose frequency: 1. An infant 2. A toddler 3. A teenager PEDIATRIC DRUG ADMINISTRATION Intramuscular Use a small gauge needle of less than 1 inch. Site varies with age. Subcutaneous 27 or 23 gauge needle in the upper arm. Intravenous Size appropriate for vein. Same sites as adults. Caution with concentration and total fluid volumes administered. Oral Absorption is variable. Vomiting is common. Use needle-less syringe for administration. Other Rectal: absorption is unpredictable. Topical: vasoconstriction is common in young children. NEARPOD: PEDIATRIC CONSENT NEARPOD PEDIATRIC CONSENT 1. Discuss consent for treatment as it applies to the pediatric population. 2. How does the age of the patient affect consent? 3. How does the primary problem affect consent? 4. What options do you have in cases where you are unable to obtain parental consent? GERIATRICS PHARMACOTHERAPY IN THE ELDERLY  Prevalence of prescription drug use increases substantially with age. Survey data from 2010–2011 indicate that almost 90% of older adults regularly take at least 1 prescription drug, almost 80% regularly take at least 2 prescription drugs, and 36% take at least 5 prescription drugs.1 When over-the-counter and dietary supplements are included, these prevalence rates increase substantially.  Despite an age-related decrease in small-bowel surface area, slowed gastric emptying, and an increase in gastric pH, changes in drug absorption tend to be clinically inconsequential for most drugs. 2  Elderly patients are more likely to have chronic disorders that may be worsened by the drug or affect drug response. Their physiologic reserves are generally reduced and can be further reduced by acute and chronic disorders.  Many elderly patients live on a fixed income and/or have mobility difficulties so they may be less able to afford or obtain drugs. PHARMACOKINETI C CHANGES PHARMACOKINETIC CHANGES Absorption Delayed gastric emptying, consumption of numerous medications and non-prescription drugs, altered nutritional habits Distribution Reduced lean body mass, total body water, and increased fat percentage. PHARMACOKINETIC CHANGES Metabolism Reduction in Phase I metabolism. First-pass metabolism is also affected by aging, decreasing by about 1% per year after age 40. Co-morbidities that affect cardiac output. Elimination Reduced renal clearance. Renal function is dynamic, maintenance doses of drugs may need adjustment when patients become ill or dehydrated or have recently recovered from dehydration. PHARMACODYNAMIC CHANGES  Differences may be due to changes in drug-receptor interaction, in post-receptor events, or in adaptive homeostatic responses and, among frail patients, are often due to pathologic changes in organs.  Older adults are particularly sensitive to anticholinergic drug effects.  Older adults, most notably those with cognitive impairment, are particularly prone to CNS adverse effects of such drugs and may become confused and drowsy. PROBLEMATI C DRUGS IN THE ELDERLY PREVENTABLE CAUSES OF DRUG- RELATED EVENTS NEARPOD QUESTION 3 NEARPOD QUESTION 3  You are called to the residence of a sweet little elderly patient with generalized malaise. When you ask about medications, you are handed a blister pack of meds with no labels, just the pharmacy sticker. The patient is unable to tell you the names of any of their drugs. How will you determine what meds are in the pack? NEARPOD QUESTION 4 NEARPOD QUESTION 4  You are called to the residence of a lovely elderly couple, one of whom is feeling unwell. Family of the couple have made a summary sheet of medical information for each but you are having difficulty determining if the medication list is current and being adhered to.  Discuss common social complications of medication adherence in the elderly. QUESTIONS? lavergn@algonquincolleg e.com