Introduction to Pharmacology

Pharmacology Defined

• Pharmacology involves studying the interactions of drugs with biological or physiological systems.
• It includes investigating what happens to a drug inside the body.
• Pharmacology encompasses the origins, production, and effects of drugs on the body.
• Pharmacology also considers side effects, poisoning cases, and their treatments.

Subfields of Pharmacology

• Pharmacokinetics studies how the body affects a drug.
• Pharmacodynamics studies how a drug affects the body.
• Clinical pharmacology focuses on the clinical applications and effects of drugs in humans.
• Pharmacotherapy involves treating diseases or relieving symptoms using drugs.
• Chemotherapy uses specific drugs to eliminate infecting organisms or cancer cells with minimal harm to host cells.
• Pharmacoepidemiology studies the effects of drugs on populations.
• Pharmacoeconomics assesses the cost-effectiveness of drug therapy and overall medication costs.
• Pharmacogenetics studies how genetic variations influence drug treatment outcomes, explaining differences in patient sensitivity to drugs.
• Toxicology studies the symptoms, mechanisms, treatments, and detection of poisoning caused by chemical substances.

Pharmacokinetics

• Pharmacokinetics examines the movement of drugs within the body and how the body modifies the drug.
• This branch studies absorption, distribution, metabolism, and excretion processes.
• Pharmacokinetics studies the relationship between these processes and the onset, duration, and intensity of drug effects.
• In essence, pharmacokinetics explains what the body does to the drug.

Pharmacodynamics

• Pharmacodynamics examines the biochemical and physiological effects of drugs on the body.
• This branch studies the mechanisms of action of drugs, with most drugs requiring binding to a receptor to exert an effect.
• Pharmacodynamics explains what the drug does to the body.

Clinical Pharmacology

• Clinical pharmacology focuses on drugs and their clinical applications.
• This area of study examines the effects of drugs on human physiology and the body's responses to these drugs.

Pharmacotherapy

• Pharmacotherapy is the area of pharmacology involved with using drugs to treat diseases, or to relieve symptoms.

Chemotherapy

• Chemotherapy is the area of pharmacology involved with treating systemic infections, or cancer.
• Chemotherapy leverages specific drugs to eliminate the infecting organism, or cancer cells.
• Chemotherapy needs to achieve the above objective, while having little to no effect on host cells.

Pharmacoepidemiology

• Pharmacoepidemiology is the study of the effects of drugs on a population.

Pharmacoeconomics

• Pharmacoeconomics is the study of the cost-effectiveness of drug therapy.
• Pharmacoeconomics also considers the overall cost of medication.

Pharmacogenetics

• Pharmacogenetics is the field of science that aims to understand how genetic variation influences drug treatment outcomes.
• Individual patients may respond to certain drugs with greater than normal sensitivity.

Toxicology

• Toxicology is the science of poisons.
• Toxicology studies the symptoms, mechanisms, treatment, and detection of poisoning caused by various chemical substances.
• "Every drug is a poison; what distinguishes a drug from poison is the dose."
• Drugs can be beneficial, but drugs that are not used correctly, or appropriately, can cause harm to health, as well as social and or economic harm.

Pharmacological Studies: In Vitro and In Vivo

• In vitro studies are conducted outside a living organism.
• These studies normally take place in controlled environments, such as a test tube, or petri dish.
• In vivo Studies are conducted within a living organism.
• Pharmacological studies determine the most appropriate drug for prophylaxis, treatment and diagnosis of diseases.

Definition of a Drug

• A drug is a mixture with a chemically active compound.
• The active compound can be of animal, plant, or biological origin.
• These compounds influence biological processes.
• According to the World Health Organization (WHO), a drug is a substance that modifies physiological systems or pathological conditions for human benefit.

Pharmaceutical Forms and Excipients

• Drugs are combined with specific excipients.
• Excipients are inactive ingredients that create pharmaceutical forms.
• Pharmaceutical forms allow for easier administration to humans.
• A pharmaceutical form is the presentation form of a drug.

Purpose of Drug Therapy

• Prophylaxis is the prevention of disease using drug therapy.
• Diagnosis is the identification of a disease with drug therapy.
• Treatment is managing or curing a disease through drug therapy.
• Control is keeping a disease under control/management using drug therapy.

Types of Treatment

• Radical treatment eliminates the cause of a disease (e.g., infection treatment).
• Symptomatic or palliative treatment relieves symptoms without addressing the underlying cause (e.g., using an analgesic for tooth pain).
• Prophylactic or preventive treatment involves drug administration to prevent potential diseases.

Key Characteristics of Drug Action

• Selectivity: The drug should target only the specific structure, organ, or system to avoid unwanted effects.
• Temporary Effect: The drug’s effect should cease once treatment is discontinued; permanent effects are characteristic of poisons.
• Dose-Dependent Effect: The drug's effect depends on the administered dose, with dose referring to the amount of drug given at one time.

Sources of Drugs

• Natural Sources:
  • Plants: Leaves, roots, sap, seeds, bark, etc.
  • Animals: Hormones and enzymes.
  • Microorganisms: Bacteria and fungi produce antibiotics (e.g., Penicillin).
  • Minerals: Inorganic sources like sodium chloride (NaCl) and magnesium salts.
• Synthetically Derived Drugs:
  • Drugs produced through chemical synthesis.
  • Synthetically derived drugs are not extracted from natural sources.

Classification of Drugs

• Based on Chemical Structure:
  • Classification that considers the pharmacological effects of drug chemical structure.
  • Examples, choline esters, and organic phosphates.
• Based on Site of Action:
  • Drugs that affect the digestive and nervous systems.
  • Drugs that affect endocrine system.
• Based on Therapeutic Use:
  • Antihypertensives (for high blood pressure).
  • Antipyretics (fever reducers).

Drug Naming System

• Chemical Name: Based on IUPAC nomenclature, describes the chemical structure of the drug (e.g., Acetylsalicylic acid).
• Generic Name: The standard name used in medicine, pharmacy, and healthcare (e.g., Aspirin).
• Brand Name: Given by the manufacturer; a single drug can have multiple brand names (e.g., Coraspin).

Drug Dosages

• Dose: The amount of a drug at one time.
• Daily Dose: The total amount of drug in a 24-hour period.
• Maintenance Dose: Keeps blood levels stable and maintains the therapeutic effect.
• Lethal Dose: Causes death.
• Therapeutic Dose: Produces the desired therapeutic effect.

Adverse Drug Effects

• Side Effect: Unintended effects at normal dosage.
• Toxic Effect: Harmful reaction causing discomfort, life-threatening conditions, or death.
• The benefit/risk ratio should always be carefully considered, since drugs can sometimes cause toxic effects at usual doses.

Indications and Contraindications

• Indication: A condition or symptom requiring specific treatment or medical intervention.
• Contraindication: A condition or factor preventing a particular treatment or medical procedure.

Bioavailability

• Bioavailability: the portion of a drug that reaches the systemic circulation without being chemical modified.

Drug Formulation and Pharmaceutical Forms

• Drugs are generally not used in their pure form.
• Drugs are combined with active drugs and inactive excipients, to ensure proper administration.
• These preparations are called pharmaceutical forms (e.g., ampoule, coated tablet, suppository).
• Drug formulation mixes the bioactive component with excipients according to specific formulations.

Solid and Semi-Solid Forms

• Tablets: Can be chewable, effervescent, enteric-coated, sublingual, or buccal.
• Capsules: Encapsulated drugs.
• Powders: fine particulates

Pharmaceutical Forms

• Suppositories: intended for rectal or vaginal administration.
• Solutions: Can be oral, injectable, ophthalmic, otic, or nasal.
• Suspensions: Shake before using.
• Emulsions: immiscible liquid, one dispersed as small droplets.
• Syrups and Elixirs: liquid medicinal vehicles.
• Topical Forms: intended for topical administrations, such as Creams, Ointments, and Gels.
• Patches: Transdermal.
• Gaseous Forms: Aerosols, inhalers, and nebulizers.

Tablets

• Tablets absorb the water in the GI tract, swell, and disintegrate.
• Chewable Tablets: Intended to be chewed before swallowing, with medicinal compounds that do not leave a bitter, or unpleasant taste.
• Sublingual Tablet: Placed under the tongue to be absorbed into the bloodstream through the oral mucosa.
• Effervescent Tablet: Solid form containing acids that release carbon dioxide when dissolved, intended to dissolve, or disperse in water, before administering.
• Enteric-Coated Tablet: has a coating that prevents dissolving in the stomach to protect it from dissolving in the acidic environment. This protects sensitive drugs from stomach acid while preventing gastric irritation.
• Buccal Tablet: Placed between the cheek and gum to dissolve slowly. This allows gradual absorption of the drug through the oral mucosa.

Capsules

• Capsules: Cylindrical gelatin shells encase solid or liquid drugs, making them easier to swallow and masking unpleasant tastes/odors.
• Capsules are available in a variety of sizes and colors for easy identification.

Pastille

• Pastilles: Solid, round, or oval form made from a flavored sugar base and designed to dissolve slowly in the mouth for localized effects (e.g., throat soothing).

Powders

• Powders: Made by grinding synthetic or natural drugs into a fine particulate.
• Powders are usually taken orally or dissolved in water before use.

Suppository

• Suppositories: cone shaped preparations for rectal administration, that contain a fatty base, that remains solid at standard room temperature, and melt at body temperature.
• Ovule is a suppository-like dosage form prepared for vaginal administration in women.

Liquid Dosage Forms

• Solutions: A preparation made by dissolving the active drug ingredient in water or another solvent.
• Solutions are called a gargle, when applied orally.
• They can be given as drops, or as ampoules for parenteral (injection) use. Injectable

Liquid Dosage Forms

• Solutions: Made by dissolving an active drug in water or another solvent.
  • Applied as drops to the eyes, ears, or nose.
• Injectable Solutions: sterile solutions designed for injection into the body.
• Suspension: A liquid dosage form where solid drug particles remain dispersed. Due to sedimentation, suspensions need to be mixed before use.
• Post-dilution suspensions should be kept in the refrigerator, and generally only have a 15-day shelf life.
• Ampoules: A sealed glass container that is broken open just prior to injection.
• Ampoules general contains a single does of medication.
• Vial (Flacon) A glass container with a rubber cup, where the drug is drawn into a syringe.

Transdermal patch

• Transdermal patch contains a therapeutic delivery system that allows drugs to be absorbed through the skin, into the blood stream. A special system that allows the drug to be absorbed through the skin and pass into the bloodstream.
• Transdermal patches are long acting, and provide continued drug release.

Gaseous Dosage Forms and Devices

• Devices that are gaseous, or volatile liquids can be administered through inhalation, with various face masks, mouthpieces, and or endotracheal tube.
• Inhalers: Deliver mediations directly to the lungs, in fine powder, or vapor form.
• Nebulizers convert liquid mediations into a fine vapor, to be delivered to the lungs through inhalation.