Drugs and the Body

Nhelia B. Perez, RN, MSNPCU - MJCN

Pharmacokinetics

Phases of Pharmacokinetic• Absorption

- maybe reduced if the villi is decreased (disease, drug effect, removal of small intestines)

- may be passive (diffusion) or active carrier).

Distribution

-blood flow, drug’s affinity to the tissue protein binding effect, drug volume.

Metabolism

• Hepatic role• Liver diseases• Half life

Excretion

• Kidneys• Kidney diseases

PHARMACODYNAMICS

• DRUG ACTIONS• To replace or act as substitutes for

missing chemicals.• To increase or stimulate certain cellular

activities.• To depress or slow cellular activities.• To interfere with the functioning of foreign

cells, such as invading microorganisms or neoplasms.

RECEPTOR SITES• React with certain chemicals to cause

an effect within the cell. • Some drugs directly interact with

receptor sites to cause the same activity that natural chemicals would cause at the site. (agonist)

• Other drugs prevent the breakdown of natural chemicals that are stimulating the receptor sites.

• Some drugs react with receptor sites to block normal stimulation, producing no effect.

• Other drugs react with specific receptor sites on a cell and by reacting there, prevent the reaction of another chemical with a different receptor site on that cell.

PHARMACODYNAMICS

• Critical Concentration• Loading Dose• Dynamic Equilibrium• Absorption• Administration• First pass effect• Distribution• Protein binding• Blood-Brain barrier

• Placenta and Breast Milk• Biotransformation• Excretion• Half-Life

FACTORS INFLUENCING DRUG EFFECTS

• Weight• Age• Gender• Physiological factors• Pathological factors• Genetic factors• Immunological factors• Psychological factors• Environmental factors

• Tolerance• Cumulation• Drug-drug or drug-alternative

therapy interactions• Drug laboratory test interactions

Adverse Effects of

Drugs

TOXIC EFFECTS OF DRUGS

SIDE EFFECTS

• Problems that occur when treatment goes beyond the desired effect. Or problems that occur in addition to the desired therapeutic effect.

ADVERSE EFFECTS• 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 undesirable or unpleasant.

• The patient is taking too much or too little of the drug, leading to adverse effects

Types of Adverse Effects

• Primary actions– Overdose: extension of the

desired effect• Secondary actions

– Undesired effects produced in addition to the pharmacologic effect

• Hypersensitivity reactions– Excessive response to the

primary or secondary effect of the drug

Drug Allergy

• Can occur when the body forms antibodies to a particular drug.

• It may be anaphylactic, cytotoxic, serum sickness or delayed allergic reaction.

Idiosyncratic Reactions

• also known as type B reactions, are drug reactions which occur rarely and unpredictably amongst the population. 

• They frequently occur with exposure to new drugs, as they have not been fully tested and the full range of possible side effects have not been discovered; they may also be listed as an adverse drug reaction with a drug, but be extremely rare.

Teratogenic Effect

• These effects are classed as deterministic, which means that the severity as well as incidence is related to dose.

• The combined consequences of consuming a harmful substance, such as alcohol, on a developing fetus; may manifest itself as growth deficiency and/or mental retardation; fetal alcohol syndrome is an example.

LET’S TAKE A BREAK!!!

Nursing Management

RIGHTS IN DRUG ADMINISTRATION

• Right Patient• Right Route• Right Drug• Right Frequency• Right Dose

• Right Approach• Right Assessment• Right to refuse• Right Education• Right Evaluation• Right Documentation

Nursing Management

• Nursing : An Art and a Science

• The Nursing Process

1. Assessment

2. Nursing Diagnosis

3. Planning

4. Interventions

5. Evaluation

ASSESSMENT

• History

- chronic conditions

- Drug Use

- Allergies

- level of education

- level of understanding of Disease and therapy

- Social Supports- Financial Supports- Pattern of Health Care

- Physical Assessment

1. weight

2. age

3. Physical Parameters r/t disease or drug effects

NURSING DIAGNOSIS

• IT MAY BE:

1. two part

2. three part• Should be based on NANDA

PLANNING

• Should be SMART• Can be short term or long

term

INTERVENTIONS• 7 points to Proper Drug Administration

1.Drug

2.Storage

3.Route

4.Dosage

5.Preparation

6.Timing

7. recording

Comfort measures• Placebo effect• Managing adverse effects• Lifestyle adjustment• Patient and Family Education

KEY ELEMENTS TO PATIENT EDUCATION

• Name, Dose and action of Drug• Timing of Administration• Special Storage and preparation

instructions• Special comfort or safety measures• Safety measures• Specific points about drug toxicity• Special warnings about drug

discontinuation

EVALUATION

• The evaluation is an integral part in the nursing process.

• The effectivity of the drug therapy is determined through evaluation.

Dosage Calculations

Drug Order

• Elements of a Drug Order• Abbreviations• Interpreting Drug Orders

DOSAGE CALCULATIONS• Measuring Systems

- Metric System

- Apothecary System

- Household system

Converting between Systems

• Ratio and proportion

Calculating Dosage

• Oral Drugs• Parenteral Drugs• Intravenous solutions• Pediatric considerations

GENERAL FORMULA

Dosage X quantity

stock

ORAL DRUGS

• Amt of drug available = amt of drug prescribed

one tablet or capsule no. of tabs or caps

PARENTERAL DRUGS

Amt of drug available = amt of drug prescribed

volume available volume to administer

Intravenous Solution

Drops/min = mL of sol pres/hr x drops delivered / mL

60 minutes / 1 hour

1. Clark's Rule for Infants or Children:Clark’s rule is based upon the weight of the child. To determine the proper dosage for children, divide child’s weight in pounds by 150 to get the correct fraction of adult dose. Example: For a 50 pound child give 50/150 (or 1/3) of the adult dose. Therefore, if the adult dose is 30 drops taken 3 times per day, the child’s dose will be 10 drops taken 3 times per day (not 30 drops taken 1 time per day!)

(Weight in pounds x (Adult dose) 150

(That's: Child's weight in pounds times adult dose divided by 150)

2. Fried's Rule for Infants and Children up to 1 to 2 Years:

(Age in Months) x (Adult Dose)

150

(That's: Child's age in months times adult dose divided by 150)

3. Young's Rule for Children from 1 year to 12 Years:Young’s rule is based upon the age of the child, regardless of its weight. It is a “rule of the thumb” method for calculating the dose of medicine to be administered to a child. The child’s age divided by age plus 12 represents the fraction of the adult dose suitable for the child.

(Age in Years) x (Adult Dose) Age + 12

(That's: Child's age in years times adult dose divided by child's age plus 12)

Problems

• Change to equivalents within the system:

1. 100 mg = ______g

2. 1500 g = ______kg

3. 0.1 L = _______ mL

4. 500 mL = _______L

Convert to units in the metric system• 150 gr = _________ g• ¼ gr = ________mg• 45 min = ______mL• 2 qt = ______L

Convert to units in the household system• 5 mL = __________tsp• 30 mL = _________tbsp

Convert the weights in the following problems• A patient weighs 170 lb. What is the

patient’s weight in kilograms?• A patient weighs 3200 g. What is the

patient’s weight in pounds?

• Robitussin cough syrup 225 mg PO is ordered. The bottle reads: 600 mg in 1 ounce. How much cough syrup should be given?

• A postoperative order is written for ¼ gr codeine every 4 hours as needed for pain. Each dose given will contain how many milligrams of codeine?

Thank you for Listening!