Basic Pharmacology Study Notes

Basic Pharmacology Study Notes

Introduction

Prepared by Prof. Ryan Reyes, these notes cover fundamental concepts in basic pharmacology, including definitions, drug effects, administration routes, pharmacokinetics, and practical applications in nursing.

Definitions and Key Concepts

1. Drug Effects:
      - Unintended Effects: Effects that occur without the intention of the healthcare provider. These effects can be predictable and may be either harmless or potentially harmful.
      - Therapeutic Effect: The desired or intended outcome from administering a drug.
      - Secondary Effect: An unintended consequence that can either be beneficial or detrimental.
      - Adverse Effect: A harmful or undesired effect that may occur with drug administration.
      - Toxic Effect: A severe adverse effect resulting from excessive drug dosage, leading to potential organ damage.

2. Overdosage and Build-Up:
      - This refers to deleterious effects stemming from an overdose or accumulation of the drug within the blood leading to toxicity.

3. Drug Interactions:
      - A situation where the administration of one drug influences the effect of another when given concurrently or sequentially.
      - Examples include iatrogenicity, which denotes side effects resulting from medical treatment, and idiosyncrasy, which refers to unusual responses to drugs.

Pharmacokinetics

1. Absorption: The process of the drug being transferred from its site of entry into the body into the bloodstream for distribution.
      - Factors affecting absorption include the route of administration, blood flow to the administration site, and the form of the drug.
      - Incorrect Statement: Drug absorption is not affected by the form of the drug.

2. Distribution: The process by which the drug is transported by bodily fluids to its action sites, metabolism, and excretion.

3. Excretion: Primary routes include urine and feces, as well as minor routes such as saliva and exhalation.

4. Hepatic First Pass Effect: An important concept that explains why oral drug doses may need to be higher than intravenous doses, as some of the drug gets metabolized in the liver before reaching systemic circulation.

Drug Administration

1. Enteral Route: Includes any method of drug administration via the gastrointestinal tract (e.g., oral, nasogastric tube, gastrostomy) but does not include nebulization.

2. Intravenous (IV) and Intramuscular (IM) Injections: Guidelines dictate that injections should not be given if circulation is impaired to ensure proper delivery and absorption.
      - Z-track technique: Used for painful IM injections to prevent the drug from irritating subcutaneous tissue.

3. Medication Errors: Medication administration errors are common; the nurse’s essential role includes:
      - Being a primary defense in preventing drug errors.
      - Adhering strictly to the "five rights" of medication administration (right patient, right drug, right dose, right route, and right time).

Dosage Calculations

1. Half-Life Calculations: To determine the amount of medication remaining in the body after a specified duration based on its half-life. For example, if a patient takes 500 mg of a medication with a half-life of 8 hours, after 16 hours, 125 mg remains.

2. Volume Calculations for IM Administration: Essential for ensuring the correct dosage is administered as per physician orders, for example:
      - If Meperidine (Demerol) is to be administered 150 mg/day at intervals (q4H), calculate the required volume based on available concentrations.

3. Drip Factor Calculations: For intravenous fluid administration, including calculations for flow rates based on the prescribed mL/hour and drip factor from the IV setup, e.g., at a rate of 125 mL/hr with a 15 gtt/mL drip factor:
      - $125 ext{ mL/hr} imes rac{15 ext{ gtt}}{1 ext{ mL}} <br>ightarrow 31.25 ext{ gtt/min}$, rounded appropriately.

Patient Identification in Medication Administration

When identifying patients who are confused, it is best practice for the nurse to ask the patient to state their name and birth date, rather than relying solely on their room number or wristband identification.

Conclusion

These pharmacology concepts form the basis of understanding drug actions, interactions, and administration protocols that are crucial for nursing practice and patient safety.