Overview of Pharmacology

Definition: Study of drugs, their properties, effects, and interactions in biological systems.
Branches:
- Pharmacodynamics: Study of drug effects and mechanisms of action.
- Pharmacokinetics: Study of drug absorption, distribution, metabolism, and excretion (ADME).

Key Concepts

Drug Classification:
- Prescription Drugs: Requires a doctor's authorization.
- Over-the-Counter (OTC) Drugs: Available without a prescription.
- Controlled Substances: Drugs with potential for abuse; regulated by law.
Mechanisms of Action:
- Receptor Interaction: Drugs bind to specific receptors to elicit effects.
- Enzyme Inhibition: Drugs may inhibit or enhance enzyme activity.
- Ion Channel Modulation: Drugs can open or close ion channels affecting cell excitability.

Pharmacokinetics

Absorption: Process of drug entering the bloodstream.
- Factors: Route of administration, drug formulation, and presence of food.
Distribution: Movement of drugs throughout the body.
- Influenced by blood flow, tissue permeability, and protein binding.
Metabolism: Biochemical modification of drugs, primarily in the liver.
- Phase I: Modification (oxidation, reduction).
- Phase II: Conjugation (addition of substances for excretion).
Excretion: Removal of drugs from the body, mainly via kidneys.

Pharmacodynamics

Dose-Response Relationship: Correlation of drug dose to its pharmacological effect.
- Potency: Amount of drug needed for a desired effect.
- Efficacy: Maximum effect a drug can produce.
Therapeutic Index: Ratio between the toxic dose and effective dose; indicates drug safety.

Drug Interactions

Synergistic Effects: Combined effect of drugs is greater than the sum of their individual effects.
Antagonistic Effects: One drug reduces or inhibits the effect of another.
Additive Effects: Combined effect of drugs equals the sum of their individual effects.

Adverse Drug Reactions (ADRs)

Types:
- Allergic Reactions: Immune system responses to a drug.
- Toxic Reactions: Harmful effects due to overdose or sensitivity.
- Idiosyncratic Reactions: Unusual responses not related to the drug's pharmacological action.

Principles of Drug Administration

Routes of Administration:
- Oral: Convenient but variable absorption.
- Intravenous (IV): Rapid effect, directly into the bloodstream.
- Intramuscular (IM): Moderate absorption rate.
- Subcutaneous (SC): Slower absorption compared to IM.
Factors Influencing Drug Activity:
- Age, weight, genetics, gender, and pre-existing conditions.

Conclusion

Pharmacology integrates science and medicine to understand how drugs interact with biological systems, assess their therapeutic potential, and ensure safe and effective use in clinical practice.

Overview of Pharmacology

Pharmacology is the study of drugs, encompassing their properties, effects, and interactions within biological systems.
Two main branches include pharmacodynamics (effects and mechanisms of action) and pharmacokinetics (absorption, distribution, metabolism, and excretion).

Key Concepts

Drug Classification:
- Prescription drugs require a doctor's approval before use.
- Over-the-counter (OTC) drugs can be purchased without a prescription.
- Controlled substances are regulated due to potential for abuse.
Mechanisms of Action:
- Drugs interact with specific receptors to trigger physiological responses.
- Enzymes can be inhibited or activated by drugs, affecting metabolic pathways.
- Modulation of ion channels by drugs can influence cell excitability.

Pharmacokinetics

Absorption involves how drugs enter the bloodstream; influenced by administration route, formulation, and food intake.
Distribution refers to the dispersion of drugs throughout the body, affected by blood flow, tissue permeability, and protein binding.
Metabolism, primarily occurring in the liver, involves two phases:
- Phase I includes chemical modifications such as oxidation.
- Phase II involves conjugation, adding substances for elimination.
Excretion is the process of drug elimination from the body, mainly through renal pathways.

Pharmacodynamics

Dose-Response Relationship measures the effect of drug dosage on its pharmacological response.
Potency indicates the amount of a drug required to produce a specific effect.
Efficacy is the maximum therapeutic response that a drug can achieve.
Therapeutic Index represents the safety margin of a drug, calculated as the ratio of toxic dose to effective dose.

Drug Interactions

Synergistic Effects occur when the combination of two drugs produces a greater effect than their individual effects.
Antagonistic Effects manifest when one drug diminishes the effect of another.
Additive Effects signify that the combined effects of drugs equal the sum of their individual actions.

Adverse Drug Reactions (ADRs)

Allergic Reactions are immune responses that occur in reaction to a drug.
Toxic Reactions result from overdosing or individual sensitivity to a drug.
Idiosyncratic Reactions are unexpected responses to a drug that are unrelated to its expected pharmacological effects.

Principles of Drug Administration

Routes of Administration:
- Oral administration is the most convenient but presents variable absorption.
- Intravenous (IV) administration provides immediate effects through direct bloodstream entry.
- Intramuscular (IM) injections have moderate absorption rates.
- Subcutaneous (SC) injections result in slower absorption compared to IM.
Factors Influencing Drug Activity include patient-specific variables such as age, weight, genetics, gender, and overall health conditions.

Conclusion

Pharmacology is a vital integration of science and medicine, focusing on drug interactions with biological systems, therapeutic assessment, and the promotion of safe clinical practices.