Copyright © 2011 by Elsevier Inc. All rights reserved. Pregnancy (Lilley p. 36) First trimester (0-3 months) is the period of greatest danger for drug-induced developmental defects Drugs cross the placenta by diffusion During the last trimester the greatest percentage of maternally absorbed drug gets to the fetus FDA pregnancy safety categories Misoprostol, a gastrointestinal prostaglandin, is contraindicated for use in pregnancy because of the effect of inducing uterine contractions. Progestins are contraindicated in pregnancy because of the possibility of birth defects. NURSING APPLICATION: Ms. Jackson's granddaughter just found out she is 8 weeks pregnant and wants to take something for nausea. What should the nurse tell her? Copyright © 2011 by Elsevier Inc. All rights reserved.

Factors Affecting Pediatric Drug Dosages (Lilley p. 37) Skin is thin and permeable Stomach lacks acid to kill bacteria Lungs have weaker mucus barriers Body temperatures less well regulated, and dehydration occurs easily Liver and kidneys are immature, impairing drug metabolism and excretion They are very susceptible to many drug interactions, toxicity, and unusual drug responses and therefore require very different dosage calculations. Many formulas for pediatric dosage calculation have been used throughout the years. Formulas involving age, weight, and body surface area (BSA) are most commonly employed as the basis for calculations. BSA-based formulas are the most accurate of these dosage formulas. Saline solutions are often given to pediatric patients who cannot take antihistamines or cough suppressants. NURSING APPLICATION: Explain to Ms. Jackson why her 5-year-old great granddaughter should not take the same amount of Tylenol as the child's mother. Copyright © 2011 by Elsevier Inc. All rights reserved.

Physiologic Changes in the Elderly Patient (Lilley p. 42) Cardiovascular Gastrointestinal Hepatic Renal Elderly patients are hospitalized frequently due to adverse drug reactions. See Table 3-4, Medications and Conditions Requiring Special Considerations in the Elderly Patient, pg. 43 NURSING APPLICATION: Why would medication be needed to help with incontinence? Explain how the elderly patient may have decrease renal function. Copyright © 2011 by Elsevier Inc. All rights reserved.

The Elderly: Pharmacokinetics (Lilley p. 42) Absorption Gastric pH less acidic Slowed gastric emptying Movement through GI tract slower Reduced blood flow to the GI tract Reduced absorptive surface area due to flattened intestinal villi The functioning of several organ systems slowly declines. The collective physiologic changes associated with the aging process have a major effect on the disposition and action of drugs. Also discuss changes in distribution, metabolism, and excretion. (Table 3-3) NURSING APPLICATION: Explain how polypharmacy could be problematic for Ms. Jackson. Copyright © 2011 by Elsevier Inc. All rights reserved.

The Elderly: Problematic Medications (Lilley p. 43) Analgesics, including NSAIDs Anticoagulants Anticholinergics Antidepressants Antihypertensives Cardiac glycosides (digoxin) Sedatives and hypnotics Thiazide diuretics More complicated medication regimens predispose elderly patients to self-medication errors, especially those with reduced visual acuity and manual dexterity. Lack of adequate patient education and understanding of their drug regimens, and use of multiple prescribers and multiple pharmacies Aging changes body composition and organ function. NURSING APPLICATION: Discuss how thiazides can cause fatigue for the elderly patient. Copyright © 2011 by Elsevier Inc. All rights reserved.

U.S. FDA Drug Approval Process (Lilley p. 53) Preclinical investigational drug studies Informed consent Clinical phases of investigational drug studies Phase I Phase II Phase III Phase IV FDA is responsible for approving drugs for clinical safety and efficacy before they are brought to the market. There are stringent steps, each of which may take years, that must be approved before the drug can be approved. The drug approval process is quite complex and prolonged. It normally begins with preclinical testing phases, which include in vitro studies (using tissue samples and cell cultures) and animal studies. Clinical (human) studies follow the preclinical phase. There are four clinical phases. The drug is put on the market after phase III is completed if an investigational new drug application submitted by the manufacturer is approved by the FDA. Phase IV consists of postmarketing studies. The collective goal of these phases is to provide information on the safety, toxicity, efficacy, potency, bioavailability, and purity of the new drug. NURSING APPLICATION: Explain the process that was taken to approve the Ms. Jackson's medications. Copyright © 2011 by Elsevier Inc. All rights reserved.

Cultural Considerations (Lilley p. 50) Assess the influence of a patient’s cultural beliefs, values, and customs Drug polymorphism Compliance level with therapy Environmental considerations Genetic factors Varying responses to specific drugs Perform a cultural assessment to determine factors that relate to the beliefs of the patient. Understand that each nurse brings beliefs about health practices that affect relationships with patients. NURSING APPLICATION: What culture or ethnic factors can be important when caring for Ms. Jackson? Copyright © 2011 by Elsevier Inc. All rights reserved.

Copyright © 2011 by Elsevier Inc. All rights reserved. Ratios (Gray Morris p. 37) Used to indicate relationship between two numbers Numbers are separated by a colon (:) Colon indicates division Numerator on left : Denominator on right Example: 1:3 is the same as 1/3 Ratio and proportion is one logical method for calculating medications. It can be used to calculate all types of medication problems. Nurses use ratios to calculate and to check medication dosages. Some medications express the strength of the solution by using a ratio. The use of ratio and proportion is a logical approach to calculating medication dosages. NURSING APPLICATION: Discuss how ratios are important in determining the correct number of tablets to give Ms. Jackson. Copyright © 2011 by Elsevier Inc. All rights reserved.

Copyright © 2011 by Elsevier Inc. All rights reserved. Proportions (p. 38) An equation of two ratios of equal value Written in any of following formats Example: 3:4 = 6:8 (separated with equals) 3:4 :: 6:8 (separated with double colon) 3/4 = 6/8 (written as a fraction) A proportion is an equation of two ratios of equal value. The terms of the first ratio have a relationship to the terms of the second ratio Read as “3 is to 4 equals 6 is to 8” or three fourths equals six eighths when expressed as a fraction. NURSING APPLICATION: Ms. Jackson is to take 1000 mg of a medication, and the medication is available in only 500 mg capsules. How many capsules should she receive? Copyright © 2011 by Elsevier Inc. All rights reserved.

Proportion: Dosage Calculation (p. 41) R(ratio) and P(proportion) is to solve for x in medications Example: If there are 500 mg in 1 capsule, how many milligrams are delivered in 2 capsules? 1 cap : 500 mg = 2 caps : x mg 1(x) = 500(2) 1(x) = 1000 x = 1000 mg In dosage calculation, ratio and proportion may be used to represent the weight of a medication that is in tablet or capsule form. Another use of ratio and proportion in dosage calculation is to express liquid medications used for oral administration and for injection. When stating a dosage of a liquid medication, a ratio expresses the weight (strength) of a medication in a certain volume of solution. NURSING APPLICATION: Ms. Jackson is taking a liquid medication that has 250 mg/mL. How many milligrams would she receive if she took 2 milliliters? Copyright © 2011 by Elsevier Inc. All rights reserved.

Determining the Percentage of a Quantity (p. 51) Change the given percentage to a decimal or fraction, then multiply the decimal or fraction by the number Example: A client reports he drank 25% of his 8-ounce cup of tea. Determine how much tea the client drank. Health care professionals see percentages written with medications (e.g., magnesium sulfate 50%). In addition to its use with medications, percentage is also used in the assessment of burns. The size of a burn (percentage of injured skin) is determined by using the rule of nines in an adult. Remember that percent means parts per 100. NURSING APPLICATION: Ms. Jackson is dehydrated, and the nurse is to encourage her to drink more fluids. If she drank 3/4 of an 8 ounce glass of water, how many ounces would the nurse record that she drank? Copyright © 2011 by Elsevier Inc. All rights reserved.

Determining What Percentage One Number Is of Another (p. 51) Make a fraction with the numbers: The denominator is the number after the word “of,” and the other number is the numerator Convert to a decimal, then to a percentage Example: 12 is what percentage of 60? To change a fraction to a percentage, multiply the fraction by 100, reduce if necessary, and add the percent sign. This can also be done by changing the fraction to a decimal, multiplying by 100, and adding the percent sign. Multiplying by 100 is the same as moving the decimal point two places to the right. NURSING APPLICATION: What percentage of the 8 ounces of water did Ms. Jackson drink? Copyright © 2011 by Elsevier Inc. All rights reserved.