Basic Principles of Pharmacology
To understand the basic principles, it is first important to understand what each of them mean. Pharmacodynamics is defined as the effect of drugs on the body, including the concepts of drug-receptor interaction, drug-receptor activity, dose-response relationship, and drug potency and efficiency. Pharmacokinetics is the movement of the drug throughout the body and includes absorption, distribution, metabolism, and elimination.
Absorption is the movement of a drug from its site of administration into the blood. Distribution is the movement of absorbed drug in bodily fluids throughout the body to target tissues, with the requirement of adequate blood flow. Metabolism is the chemical change of drug structure to enhance excretion, inactivate the drug, increase therapeutic action, activate a prodrug, and increase or decrease toxicity. The final pharmacokinetic concept is elimination which is the removal of the drug from the body by organs of elimination
Rational Drug Selection
Now that the underlying concepts of pharmacology have been covered, how then is the drug selected? The process includes first defining what the patient’s problem is, specifying the therapeutic objective, collaboration with the patient, choosing the treatment, educating the patient, and monitoring the effectiveness. Being current in evidence based practice is imperative in that medication therapy is constantly evolving.
Adverse Drug Reactions
Every drug has the potential to cause harm. Certain criteria can preclude the incidence of an adverse drug reaction including:
· Body mass
· Time of Administration
· Pathological State
· Genetic factors
· Psychological factors
Types of Adverse Reactions
· ADRs are categorized as types.
· Type A are reactions that are predictable
· Type B are allergic responses
· Type 1 are anaphylactic and immediate
· Type II are cytotoxic and also called an autoimmune response
· Type III are complex immune reactions and are also called serum sickness
· Type IV are cell mediated, delayed hypersensitivity
· Type C are cumulative effects of a drug from chronic use
· Type D are delayed reactions that not apparent initially after the drug is taken, and are teratogens and carcinogens
Categories exist for the use of drugs during pregnancy
Factors that Foster Positive Outcomes
One of the most important factors in fostering positive outcomes is patient education. It is also key in promoting adherence to drug regimens, as well as involving the patient with the plan.
Pharmacogenomics is the branch of pharmacology which deals with the influence of genetic variation on drug response in patients by correlating gene expression with a drug’s efficacy or toxicity. Specific variations include CYP 450 enzymes, P-Glycoprotein, and phenotypes.
Keep in mind that food may affect drug absorption, drug metabolism, drug excretion and conversely may affect nutrient status. There are also foods that claim to have a medicinal effect when ingested. These include fiber, vitamins and minerals, fatty acids, plant sterols. And pre-probiotics and symbiotics.
Herbal and Complementary Therapies
Phytomedicine is the practice of using plants or plant parts to achieve a therapeutic cure. Primarily these are derived from a plant or one of it’s components. In addition, pharmacognosy is a part of pharmacology that uses the chemical from plants, molds, fungi, insets, and marine animals for medicinal purposes.
As an advanced practice nurse, it is essential to remember that herbs, in the United States, are under the umbrella of foods and as such are not regulated by the Food and Drug Administration. Since they are not regulated, there can be a wide variation in the components of the herbs,
The condition must Over the Counter Medications
All OTC drugs have the following characteristics:
1. They must be safe
2. They have low potential fpr misuse or abuse
3. They have the ability to be managed just by the patient
4. They can be labeled
5. The patient must have the ability to self-diagnose the condition
Concerns arise with these characteristics. The patient, being the one diagnosing, may be treating a serious illness that worsened due to lack of appropriate treatment. In addition just because the medication is over the counter does not mean there are not side effects, and that there may be drug interactions.
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