1. The action of a medication occurs when it interacts with specific target sites in the body, such as receptors or enzymes, and produces a desired effect.
2. Medications can alter the body's physiological processes through various mechanisms. Some common ways include:
- Receptor binding: Medications can bind to specific receptors in the body, either activating or blocking them, which can modify the body's response to certain stimuli.
- Enzyme inhibition: Drugs can inhibit or block specific enzymes, which are responsible for catalyzing chemical reactions in the body. This can alter the rate or outcome of certain physiological processes.
- Ion channel modulation: Certain medications can modify the activity of ion channels, which are responsible for controlling the movement of ions across cell membranes. This can affect nerve conduction, muscle contraction, and other physiological processes.
- Altering neurotransmitter levels: Some drugs can affect the levels of neurotransmitters in the brain, either by increasing or decreasing their synthesis, release, or reuptake. This can impact mood, behavior, and other physiological functions.
3. The strength of medication action can be determined through several factors, including the dose of the medication administered, its concentration at the target site, the affinity of the drug for its target receptors, and the duration of drug-receptor interaction.
4. Drug activity can be divided into two main categories:
- Pharmacokinetics: This refers to how the body processes the drug, including its absorption, distribution, metabolism, and elimination.
- Pharmacodynamics: This relates to the specific effects of the drug on the body, such as its mechanism of action, desired therapeutic effects, and side effects.
5. Pharmacokinetics is the study of how drugs are absorbed, distributed, metabolized, and eliminated by the body. It encompasses processes such as drug absorption from the site of administration, distribution throughout the body, metabolism by enzymes, and excretion through various routes.
6. Drugs can be absorbed into the body through multiple routes, including:
- Oral administration: Drugs are taken by mouth and pass through the gastrointestinal tract where they are absorbed into the bloodstream.
- Intravenous administration: Drugs are directly injected into a vein, providing rapid and complete absorption.
- Transdermal administration: Drugs are applied to the skin and absorbed through the layers into the bloodstream.
- Inhalation: Drugs in the form of gases, vapors, or aerosols are inhaled into the lungs, where they are absorbed into the bloodstream.
- Subcutaneous or intramuscular injection: Drugs are injected beneath the skin or into a muscle, allowing for absorption into the bloodstream.
7. Medication distribution refers to the process by which drugs are transported from the bloodstream to various tissues and organs in the body. Distribution is influenced by factors such as blood flow to different organs, drug solubility, binding to plasma proteins, and permeability of cell membranes.
8. Pharmacodynamics is the study of how drugs interact with the body's receptors or target sites to produce their effects. It involves understanding the mechanism of action, therapeutic effects, and potential side effects of medications.
9. In pharmacodynamics, there are different types of effects that drugs can produce:
- Therapeutic effects: These are the desired effects of a medication that are intended to treat a specific condition or symptom.
- Side effects: These are unintended effects of a medication that may occur in addition to its therapeutic effects.
- Adverse effects: These are undesired effects that can be harmful or potentially dangerous.
- Toxic effects: These are severe adverse effects that can result from high doses or prolonged use of medications.
10. Medication side effects are unintended effects that can occur alongside the desired therapeutic effects of a medication. Factors that can influence medication side effects include:
- Individual variability: Different individuals may have different reactions to the same medication.
- Dosage: The dose of the medication can influence the likelihood and severity of side effects.
- Drug interactions: When medications are used together, they can interact and increase the risk of side effects.
- Age and health status: Older individuals or those with certain medical conditions may be more susceptible to side effects.
- Genetic factors: Some individuals may have genetic variations that make them more or less prone to certain side effects.
11. Passive diffusion is a process in which drugs move across cell membranes, driven by concentration gradients, without the need for energy expenditure. Active diffusion, on the other hand, involves the use of energy or carrier proteins to transport drugs against a concentration gradient.
12. The two divisions of routes of drug administration are:
- Enteral administration: Involves the administration of drugs through the gastrointestinal tract, such as oral or rectal routes.
- Parenteral administration: Involves the administration of drugs through routes other than the gastrointestinal tract, such as injections (intravenous, intramuscular, subcutaneous), inhalation, or transdermal absorption.
13. Medications can have various effects on the body, including therapeutic effects, side effects, adverse effects, and toxic effects. Therapeutic effects are the desired effects that are intended to treat a specific condition, while side effects are unintended effects that may occur alongside the therapeutic effects. Adverse effects are undesired effects that can be harmful or dangerous, and toxic effects are severe adverse effects that can result from high doses or prolonged use of medications.
14. Allergic reactions to medications occur when the immune system mistakenly identifies a drug as a harmful substance and triggers an immune response. This response can cause symptoms ranging from mild, such as skin rashes or itching, to severe, such as difficulty breathing or anaphylaxis.
15. There are four types of allergic reactions to medications, known as hypersensitivity reactions:
- Type I (Immediate hypersensitivity): This is an immediate allergic reaction that occurs within minutes to hours after exposure to the drug. It involves the release of histamine and other chemicals, causing symptoms like hives, itching, swelling, and in severe cases, anaphylaxis.
- Type II (Cytotoxic): This reaction involves the binding of drug-induced antibodies to cells, leading to their destruction. It can result in conditions like hemolytic anemia or thrombocytopenia.
- Type III (Immune complex): Immune complexes form when drugs bind to antibodies and get deposited in tissues, leading to inflammation. This can cause conditions like serum sickness or drug-induced lupus.
- Type IV (Delayed hypersensitivity): This reaction occurs hours to days after drug exposure and involves the activation of T cells. It leads to a localized or systemic inflammatory response, causing symptoms such as rash, blistering, or organ damage.
