Absorption
Absorption is the process through which a drug enters the bloodstream. Factors that influence absorption include the drug's
formulation, the route of administration (oral, intravenous, etc.), and the patient's
physiological condition. For example, oral medications must pass through the digestive tract, where they may be affected by
gastric pH and the presence of food.
Distribution
Once absorbed, the drug is distributed throughout the body via the bloodstream. Distribution can be affected by the drug's
lipophilicity (ability to dissolve in fats), the extent of
protein binding, and the presence of barriers such as the
blood-brain barrier. Nurses need to understand these factors to anticipate how a drug might reach its target tissue and what potential interactions could occur.
Metabolism
Metabolism is the process by which the body breaks down the drug, primarily occurring in the liver. Enzymes like those in the
cytochrome P450 system play a significant role. Factors such as
age, liver function, and the presence of other medications can impact metabolism. Nurses should be aware of these factors to adjust dosages and avoid
toxicity.
Excretion
Excretion is the process of eliminating the drug from the body, primarily through the kidneys.
Renal function is an important consideration, especially in elderly patients or those with
kidney disease. Monitoring
urine output and kidney function tests can help nurses ensure that drugs are being properly excreted.
Drug-Receptor Interaction
Drugs exert their effects by binding to specific
receptors in the body. This interaction can either stimulate (agonist) or inhibit (antagonist) a physiological response. Knowing the type of interaction helps nurses predict the drug's effects and potential side effects.
Dose-Response Relationship
The dose-response relationship describes how the drug's effect changes with varying doses. A
higher dose may produce a greater effect up to a certain point, beyond which no additional benefit is seen, and toxicity may occur. Nurses must understand this to administer the correct dose and to educate patients on the importance of adhering to prescribed dosages.
Therapeutic Index
The therapeutic index is the ratio between the toxic dose and the therapeutic dose of a drug. A narrow therapeutic index means there is a small margin between an effective dose and a toxic dose, requiring close monitoring. Nurses should be particularly vigilant with drugs that have a narrow therapeutic index to avoid adverse effects. Administer medications safely and effectively.
Monitor patients for therapeutic and adverse effects.
Educate patients about their medications.
Adjust dosages based on individual patient factors.
Collaborate effectively with other healthcare professionals.
