Introduction to General Pharmacology
General pharmacology covers the fundamental principles of pharmacology, including Drug discovery and development, Souces of Drugs, Dosage forms, Routes of drug administration, Pharmacokinetics, Clinical Pharmacokinetics, Pharmacodynamics, Drug interactions and Adverse drug reactions (ADRs). Understanding these principles is crucial for healthcare professionals, researchers, and students to act safely and effectively using medications.
Drug Discovery and Development
The Comprehensive Guide to Drug Discovery, Development, and Clinical Trials: Everything You Need to Know
Drug Design and Screening
- Rational drug design
- High-throughput screening
- Structure-activity relationships (SAR)
Phases of Clinical Trials
- Phase I: Safety and dosage
- Phase II: Efficacy and side effects
- Phase III: Efficacy, monitoring, and comparison
- Phase IV: Post-marketing surveillance
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Sources of Drugs
Various Sources of Drugs
Drugs are substances that are used to treat or prevent diseases, relieve symptoms, or improve the overall health and well-being of individuals. There are several sources of drugs, including natural sources, synthetic sources, and semi-synthetic sources.
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Dosage Forms
Dosage Forms of the Drugs
Dosage forms refer to the different physical forms in which medications are prepared and administered. Some common dosage forms include tablets, capsules, syrups, injections, and patches.
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Routes of Drug Administration
Routes of Drug Administration
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| Enteral Routes | Description | Few Examples |
|---|---|---|
| Oral | Medication is taken by mouth in the form of tablets, capsules, or syrups | Aspirin, Paracetamol, Antibiotics |
| Sublingual | Medication is placed under the tongue to dissolve and be absorbed through the mucous membranes | Nitroglycerin, Vitamin B12 |
| Rectal | Medication is inserted into the rectum in the form of suppositories or enemas | Anti-inflammatory drugs, Laxatives |
Parenteral Routes:
| Parenteral Routes | Description | Few Examples |
|---|---|---|
| Intravenous (IV) | Medication is injected directly into a vein using a needle and syringe | Chemotherapy drugs, Painkillers |
| Intramuscular (IM) | Medication is injected into a muscle using a needle and syringe | Vaccines, Antibiotics |
| Subcutaneous (SC) | Medication is injected under the skin using a needle and syringe | Insulin, Heparin |
| Transdermal | Medication is applied to the skin in the form of a patch or cream | Nicotine patches, Hormone replacement therapy |
| Inhalation | Medication is breathed in as a mist or aerosol | Asthma medications, Anesthetics |
Pharmacokinetics
Pharmacokinetics – What the body does to Drug?
Pharmacokinetics is the study of how drugs are Absorbed, Distributed, Metabolised, and Eliminated (ADME) by the body. “It is also called what the body does to the body“. It involves the examination of how drugs move through the body, including how they are absorbed from the Gastrointestinal tract (GIT) and other sites of administration into the bloodstream, distributed to various organs and tissues, broken down/metabolised by the body’s enzymes, and eliminated through the various routes including urine, feces, or breath.
The study of pharmacokinetics helps:
- Determine the most effective dosage and frequency of a drug and
- Understand the potential risks and side effects associated with its use.
Absorption
- Passive diffusion
- Facilitated diffusion
- Active transport
- Endocytosis and exocytosis
- Factors affecting the drug absorption
Factors Affecting Oral Drug Absorption and its Bioavailability
Distribution
- Plasma protein binding
- Volume of distribution
- Tissue and organ barriers
Metabolism
- Phase I reactions: Oxidation, reduction, and hydrolysis
- Phase II reactions: Conjugation
- Enzyme induction and inhibition
- Genetic polymorphisms
Excretion
- Renal excretion
- Biliary excretion
- Other routes of excretion
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Clinical Pharmacokinetics
Clinical Pharmacokinetics
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Pharmacodynamics
Pharmacodynamics: Understanding What Drug Does to the Body
Pharmacodynamics is the study of how drugs interact with the body at the molecular, cellular, and systemic levels to produce their effects. One of the fundamental aspects of pharmacodynamics is drug-receptor interactions, which are the binding of a drug molecule to a specific receptor on a cell or tissue. This interaction can activate or inhibit the receptor and trigger downstream signaling pathways, ultimately leading to the drug’s pharmacological effects.
Drug-Receptor Interactions
- Types of receptors
- Agonists and antagonists
- Partial agonists and inverse agonists
- Allosteric modulation
Dose-Response Relationships
- Graded dose-response
- Quantal dose-response
- Therapeutic index
- Potency and efficacy
Signal Transduction Mechanisms
- G protein-coupled receptors (GPCRs)
- Ion channels
- Enzyme-linked receptors
- Intracellular receptors
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Drug Interactions
Drug Interactions
- Pharmacokinetic interactions
- Pharmacodynamic interactions
- Additive, synergistic, and antagonistic effects
- Drug-food and drug-disease interactions
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Adverse Drug Reactions (ADRs)
Adverse Drug Reactions
- Types of adverse drug reactions
- Mechanisms of adverse drug reactions
- Risk factors for adverse drug reactions
- Monitoring and reporting of adverse drug reactions
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Factors Modifying Drug Action (click here to go to this page)
Conclusion
General pharmacology lays the foundation for understanding the principles of drug actions and their interactions with living organisms. This article has provided an overview of the key chapters and topics in general pharmacology, including drug discovery and development, pharmacokinetics, pharmacodynamics, drug interactions, adverse drug reactions, and drug regulation. A strong grasp of these topics is essential for healthcare professionals, researchers, and students to safely and effectively use medications in clinical practice.
Disclaimer: This article is for informational purposes only and should not be taken as medical advice. Always consult with a healthcare professional before making any decisions related to medication or treatment.
