Pharmacology: Definition and Subfields

Pharmacology Definition

• Pharmacology examines the interaction of drugs with biological and physiological systems.
• Pharmacology investigates the effects of drugs within the body.
• Pharmacology looks at the origins, production, and effects of drugs, including side effects, poisoning cases, and treatments.

Subfields of Pharmacology

• Pharmacokinetics studies how the body affects a drug.
• Pharmacodynamics studies how a drug affects the body.
• Pharmacotherapy involves treating diseases using drugs.
• Chemotherapy uses specific drugs to eliminate infecting organisms or cancer cells without harming the host.
• Clinical Pharmacology focuses on drugs and their clinical uses, studying their effects on human physiology and the body's responses.
• Pharmacogenetics researches how genetic variations impact drug treatment outcomes, like sensitivity.
• Toxicology is the the study of poisons.

Pharmacokinetics

• Pharmacokinetics studies the movement of drugs within the body and how the body changes the drug.
• It studies the processes of absorption, distribution, metabolism, and excretion of drugs.
• Pharmacokinetics also relates these processes to the onset, duration, and intensity of drug effects.

Pharmacodynamics

• Pharmacodynamics studies the biochemical and physiological effects of drugs on the body.
• It studies the mechanisms of action of drugs.
• Most drugs need to bind to a receptor to have an effect.

Clinical Pharmacology

• Clinical pharmacology focuses on drugs, their clinical uses, and how they affect the human body.
• It studies the effects of drugs on human physiology and the body's responses to these drugs.

Pharmacotherapy

• Pharmacotherapy uses drugs to treat diseases or relieve symptoms.

Chemotherapy

• Chemotherapy involves treating systemic infections or cancer using specific drugs.
• Chemotherapy drugs eliminate infecting organisms or cancer cells while minimizing harm to host cells.

Pharmacoepidemiology

• Pharmacoepidemiology studies the effects of drugs on entire populations.

Pharmacoeconomics

• Pharmacoeconomics analyzes the cost-effectiveness of drug therapy.
• It evaluates the overall cost of medications.

Pharmacogenetics

• Pharmacogenetics studies how genetic variations influence drug responses and treatment outcomes.
• Some patients exhibit greater sensitivity to certain drugs due to their genetic makeup.

Toxicology

• Toxicology studies the symptoms, mechanisms, treatment, and detection of chemical poisoning.
• Every drug is a poison, and the dosage differentiates a poison from a medicine.
• Drugs can be beneficial when used correctly, but harmful both to health and economically when used incorrectly. Paracelsus lived from 1493-1541.

Pharmacological Studies

• In vitro studies involve testing outside a living organism, like in a test tube.
• In vivo studies involve testing within a living organism.
• Pharmacological studies help determine the best drug for diagnosis, treatment, and the prevention of diseases.

Drug Definition

• A drug is any mixture with a chemically active compound that has biological, plant, or animal origin.
• Drugs can influence biological processes.
• According to the World Health Organization (WHO), a drug is a substance that is used to modify physiological systems or pathological conditions for human benefit.

Pharmaceutical Forms

• Drugs are combined with inactive ingredients called excipients
• Excipients create pharmaceutical product to ease delivery.
• Pharmaceutical product is the final presentation form

Purpose of Drug Therapy

• Prophylaxis is the prevention of disease.
• Diagnosis is identifying a disease.
• Treatment is managing or curing a disease.
• Control is keeping a disease under control.

Types of Treatment

• Radical Treatment administers a drug to completely eliminates the cause of the disease.
• An example of radical treatment is infection treatment
• Symptomatic/Palliative Treatment involves drugs to relieve symptoms without addressing the underlying cause of the disease.
• An example of symptomatic/palliative treatment is using an analgesic to relieve pain from a tooth cavity.
• Prophylactic/Preventive Treatment involves drug administration to prevent potential disease.

Key Characteristics of Effective Drugs

• Selectivity is when a drug only affects the targeted structure, organ, or system, with no unwanted side effects.
• Temporary Effect means the drug's effects conclude once treatment is discontinued. Permanent effects are common for poisons.
• Dose-Dependent Effect when the effects depend on the administered dose.

Sources of Drugs

• Natural sources include plants (leaves, roots, sap, seeds, bark), animals (hormones and enzymes), microorganisms (bacteria and fungi), and minerals (sodium chloride, magnesium salts).
• Synthetically derived drugs are produced through chemical synthesis, not extracted from natural sources.

Drug Classification Types

• Chemical Structure: Based on the chemical structure (ex: choline esters, organic phosphates)
• Site of Action: Drugs are classified by the body parts they affect (ex: digestive, nervous and endocrine systems)
• Therapeutic Use: Antihypertensives reduce high blood pressure and antipyretics reduce fever.

Drug Naming System

• Chemical Name defines chemical structure as determined by International Union of Pure and Applied Chemistry (IUPAC) nomenclature.
• Examples: Acetylsalicylic acid, N-(4-hydroxyphenyl)acetamide (Acetaminophen)
• Generic Name (Nonproprietary Name) is the official standardized name used in medicine, pharmacy, healthcare, science and international communication.
• Examples: Aspirin, Paracetamol, Diclofenac
• Brand Name (Trade Name) is the name given by the manufacturer, so a single drug may have many names.
• Examples: Coraspin, Ataspin, Dispril

Drug Dosage Definitions

• Dose refers to the amount of a drug administered at one time.
• Daily Dose is the total amount of drug over a 24-hour period.
• Maintenance Dose is the dosage required to maintain stable blood levels and therapeutic effects.
• Lethal Dose is the amount that could cause death.
• Therapeutic Dose is a dose that yields the desired clinical results.

Adverse Drug Effects

• Side Effect are the unintended effects at normal dosages.
• Toxic Effect is a harmful event potentially causing discomfort, life-threatening situations or potentially death.
• Drugs can sometimes cause toxic effects even at normal levels, so evaluate benefit/risk carefully.

Indications versus Contraindications

• Indication means a specific condition or symptom that requires particular medical intervention.
• Contraindication means any conditional factor preventing a standard medical treatment or procedure.

Bioavailability

• Bioavailability refers to drug volume reaching system circulation.
• It reaches the systemic circulation without chemical modification.

Drug Formulation of Drugs

• Drugs are generally not used in pure form.
• Drugs are typically mixed with inactive excipients to ensure proper administration.
• These created forms are called pharmaceutical forms
• Drug formulation is mixing bioactive component with excipients.

Solid and Semisolid Dosage

• Tablet forms include chewable, effervescent, enteric coated, sublingual and buccal.
• Other forms include capsules, powders, and suppositories, including rectal or vaginal.

Liquid Dosage Forms

• Solutions can be oral, injectable, ophthalmic, otic or nasal.
• Other forms include suspensions that require shaking, emulsions, syrups elixirs, topical forms and creams.

Other Dosage Forms

• Ointments include pomades and balms.
• Gels and transdermal patches are also an another form.
• Gaseous forms- Aerosols, inhalers, and nebulizers.

Tablet Characteristics

• Tablets can absorb water in the GI tract and disintegrate.
• Chewable Tablets are chewed before being swallowed.
• They contain medicine with no bitter or unpleasant aftertaste.
• Sublingual Tablets are placed under the tongue for direct bloodstream absorption through the oral mucosa.
• Effervescent Tablets are solid dosage forms that contain acids that release carbon dioxide when dissolved in water and disperse before administering.

Special Tablet Types

• Enteric-Coated Tablets have special coating to avoid acidic stomach environment and dissolve sensitive drugs in the intestines.
• Buccal Tablets are placed between the cheek and gum , permitting a more gradual absorption of a drug via the oral mucosa.

Capsules

• Capsules encase solid or liquid drugs in cylindrical gelatin shells for easy swallowing.
• Capsules mask unpleasant tastes and odors of medication.
• Capsules are available in various colors and sizes for easy identification.

Pastilles

• Pastilles are solid, oval or round dosage form made of flavored sugar, which dissolve slowly for localized effects like throat soothing.

Powder

• Powder is made by grinding synthetic or natural drugs into a fine powder, which is then taken orally or dissolved in water.

Suppositories

• Suppositories are cone-shaped for rectal insertion.
• They are made of fatty bases that melt at body temperature.
• Ovule (Vaginal Suppository) is designed for vaginal insertion.

Solutions

• Active drug ingredients can be dissolved in water or another solvent.
• Gargling involves the oral application of the drug,.
• Drops, solutions, or ampules can be used for eye, ear, nose, or parenteral (injection routes) use.
• Injectable Solutions are sterile injection solutions for the body.

Basic Solution Information

• Solutions involve dissolving a drug in water or another solvent.
• Small volume drops can put externally or or in the eyes, ears or nose.

Suspensions

• Suspensions are liquid, with undissolved solid particles dispersed in a liquid.
• These solutions settle and must be shaken prior to use.
• After dilution, Store suspensions in refrigerator.
• Suspensions have a shelf life of 15 days.

Injections

• Injections or sterile liquids or suspensions, are delivered via a water or oil-based medium.
• They can be done subcutaneously or intramuscularly.
• Available in sealed glass ampoules or airtight, rubber-capped vials.

Ampules

• Ampules are preloaded, sealed glass containers that break open immediately before injection, each contains a single dose.

Vials

• Vials are rubber-capped, preloaded syringes into a syringe.
• Vials can be single or multi dose.

Eye and Ear Drops

• Eye Drops are designed to be liquid drug for the eye.
• Ear drops are liquid drug formulations for ears.

Emulsions

• Emulsions are when one liquid is dispersed as droplets is in another, which is typically immiscible.

Elixirs

• Elixirs are a sweetened solutions of alcohol and water, which act as a medicinal vehicle.

Syrups

• Syrups contain a high sugar concentration (over 60%) that prevents bacteria and fungi growth.

Enemas

• Enemas are solutions in the rectum.
• Enemas reduce constipation and medical examination, and clear the intestines.

Ointments and Creams

• They are externally used preparations made by mixing active ingredients with bases such as vaseline and lanolin.
• Creams contain more water than ointments.

Gels

• They are transparent or semi solid and drug is dispersed in gel base.

Transdermal Therapeutic Systems (TTS)

• TTS is a special system, where a band is applied and through the skin, the drug is absorbed into bloodstream. It is long-term/controlled medication release.

Gas dosage Forms

• Gas Dosage Forms are medicines are gases or volatile liquids.
• Gases are administered by inhalation using a mouthpiece, facemask, hood, or endotracheal tube.
• Inhalers deliver fine powder or vapor meds directly to the lungs for respiratory diseases. Inhaler meds may contain steroid.
• Nebulizers transform liquid drugs into a fine vapor for lung inhalation.