Pharmacology: Basics and Subfields

• Assoc. Prof. Büşra Ertaş of Marmara University, School of Pharmacy, Department of Pharmacology can be contacted at [email protected]

Pharmacology Basics

• Pharmacology studies the interaction of drugs with biological or physiological systems
• Pharmacology investigates what happens to a drug in the body
• Pharmacology looks at origins, production, effects, side effects, poisoning, and treatments

Subfields of Pharmacology

• Pharmacokinetics deals with drug movement within the body
• Pharmacodynamics studies the biochemical and physiological effects of drugs
• Pharmacotherapy involves disease treatment using drugs
• Chemotherapy uses specific drugs to eliminate infections or cancer
• Clinical pharmacology studies drug effects on human physiology
• Pharmacogenetics studies how genetic variations impact drug treatment outcomes
• Toxicology studies the science of poisons

Pharmacokinetics

• Pharmacokinetics studies the movement of drugs within the body and how the body modifies drugs
• Absorption, distribution, metabolism, and excretion are all examined to determine the relationship of drug effects with onset, duration, and intensity

Pharmacodynamics

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

Clinical Pharmacology

• Clinical Pharmacology is a branch that focuses on drugs and their clinical applications
• This field explores drugs effect on human physiology and responses

Pharmacotherapy

• Pharmacotherapy is the treatment of diseases or the relief of symptoms using drugs

Chemotherapy

• Chemotherapy is treatment of systemic infections or cancer
• Chemotherapy uses specific drugs that eliminate the infecting organism or cancer cells
• It does all of this while having little to no effect on the host cells.

Pharmacoepidemiology

• Pharmacoepidemiology studies the effects of drugs on a population

Pharmacoeconomics

• Pharmacoeconomics examines the cost-effectiveness of drug therapy and overall medication costs

Pharmacogenetics

• Pharmacogenetics aims to understand how genetic variations influence drug treatment outcomes
• Some patients respond to certain drugs with greater sensitivity than normal, for example

Toxicology

• Toxicology deals with the symptoms, mechanisms, treatment, and detection of poisoning caused by chemical substances
• "Every drug is a poison; what distinguishes a drug from poison is the dose."
• A drug can be beneficial or harmful when properly used, otherwise it can cause harm socially and economically

Pharmacological Studies

• In vitro studies are conducted outside a living organism
• In vivo studies are conducted within a living organism
• Pharmacological studies determine the most appropriate drug for the diagnosis, treatment, and prophylaxis (prevention) of diseases

What is a Drug

• A drug is any mixture with a chemically active compound
• Chemically active compounds can be of biological plant or animal origin
• Drugs modify physiological systems or pathological conditions for human benefit according to the World Health Organization (WHO)

About Drugs

• Substances are combined with specific excipients (inactive ingredients) instead of their pure form
• Pharmaceutical forms are created combined with specific excipients (inactive ingredients) to make creation easier to administer to humans
• Pharmaceutical form is the presentation form of a drug

Purpose of Drug Therapy

• Prophylaxis is the prevention of disease with drugs
• Drugs use in diagnosis is for identifying a disease
• Drugs are used as Treatment for managing or curing a disease
• Drugs are used to help control and keep the disease under control

Types of Treatment

• Radical treatments eliminate the cause of the disease (e.g., infection treatment)
• Symptomatic/Palliative treatments relieve symptoms without addressing the underlying cause of the disease (e.g., using an analgesic to relieve pain from a tooth cavity)
• Prophylactic/Preventive treatments are drug administrations to prevent a potential disease

Key Characteristics of Drug Action

• Selectivity states the drug should affect only the targeted structure, organ, or system while avoiding unwanted effects on other areas
• Temporary effect is defined as the cessation of the drug's effect that should cease once the treatment is discontinued (Permanent effects are characteristic of poisons)
• Dose-dependent effect means that the drug's effect is dependent on the administered dose (Dose refers to the amount of drug given at one time)

Sources of Drugs

• Natural sources of Drugs include plants, animals, microorganisms and minerals
• Plants such as Leaves, roots, sap, seeds, bark, etc., are sources of drugs
• Animals: Hormones and enzymes are derived, as sources of drugs
• Microorganisms: Bacteria and fungi produce antibiotics (e.g., Penicillin).
• Minerals (Inorganic Sources): Sodium chloride (NaCl), magnesium salts, etc.
• Drugs produced through chemical synthesis rather than being extracted from natural sources are Synthetically Derived Drugs

Classification of Drugs

• Drugs can be classified on chemical structure which can be related to pharmacological effects such as Choline esters or organic phosphates for example
• Drugs can be classified based on Site of Action for example, drugs affecting the digestive, nervous and endocrine systems
• Drugs can be classified based on Therapeutic Use with examples like, Antihypertensives (for high blood pressure), Antipyretics (fever reducers)

Drug Naming System

• A chemical name is assigned based on the International Union of Pure and Applied Chemistry (IUPAC) nomenclature, which describes the chemical structure of the drug
• Acetylsalicylic acid and N-(4-hydroxyphenyl)acetamide (Acetaminophen) is an example of a chemical name for a drug
• The generic name (Nonproprietary Name) is the standard name used in medicine, pharmacy, healthcare, and educational fields
• Aspirin, Paracetamol, and Diclofenac are example examples of Generic Names
• Brand names (Trade Name) are given by the manufacturer, meaning a single drug may have multiple brand names
• Coraspin, Ataspin, and Dispril are example of drug Brand names

Different Types of Doses

• Dose: The amount of a drug given at one time
• Daily dose: The total amount of drug administered in a 24-hour period
• Maintenance dose: The dose required to keep the drug's blood levels stable and maintain its therapeutic effect
• Lethal dose: The amount of a drug that causes death
• Therapeutic dose: The dose that produces the desired therapeutic effect

Adverse Drug Effects

• Side effects are unintended effects that occur when a drug is used at its normal dosage
• A toxic effect is a harmful reaction that can cause discomfort, life-threatening conditions, or death
• Drugs sometimes cause toxic effects, the benefit/risk ratio should be carefully considered
• Indication is a condition or symptom that necessitate a specific treatment or medical intervention
• Contraindication is defined as a condition or factor that prevents the use of a particular treatment or medical procedure

Bioavailability

• Bioavailability refers to the portion of a drug that reaches the systemic circulation without undergoing chemical modification

About Drug Forms and How They are Made

• Drugs are mixed with inactive excipients to ensure proper administration instead of using their their pure form
• Pharmaceutical forms are prepared by using active drug with in active excipients and administered for preparation
• These prepared forms are called pharmaceutical forms such as ampoule, tablet, coated tablet, syrup and a suppository
• Mixing the active ingredients with with excipients in a process known, based on specific formulations, as formulations drug formulation

Classifying pharmaceutical forms

• Solid and Semi-Solid Forms: Tablets, capsules, powders, and suppositories
• Liquid Forms: Solutions, suspensions, and emulsions
• Semisolid Forms: Ointments and gels
• Gaseous Forms: Aerosols, inhalers, and nebulizers

Tablet Variation

• Chewable Tablets are designed to be chewed before swallowing
• Chewable tablets contain medicinal substances that do not leave a bitter or unpleasant taste making them easier to consume
• Sublingual Tablets are placed under the tongue, where the drug is absorbed directly into the bloodstream through the oral mucosa
• Effervescent Tablets are a solid dosage form containing acids that release carbon dioxide when dissolved in water

Coated Tablet Variations

• Enteric-Coated Tablets have a special coating that prevents it from dissolving in the acidic conditions of the stomach
• Enteric-Coated Tablets protect sensitive drugs from stomach acid or preventing irritation of the gastric mucosa, and help them dissolve in the intestines
• Buccal Tablets are placed between the cheek and gum, where the it dissolves slowly and allows gradual absorption through the oral mucosa.

Capsule

• Cylindrical gelatin shells that encase solid or liquid drugs, making them easier to swallow
• Capsules are used to mask unpleasant tastes and odors of medications and can be used in various colors and sizes to help identification

Pastille

• Solid, round, or oval dosage form made with a flavored sugar base that is designed to dissolve slowly in the mouth
• Good for localized effect like (e.g. throat soothing)

Powder

• Powders are synthetic or natural drugs that has been ground into a fine powder and taken orally or dissolved in water before use

Suppository

• Cone-shaped pharmaceutical form designed for rectal administration made with fatty bases that remain solid at temperature but melt at body temperature
• Ovule (Vaginal Suppository) is a suppository-like dosage form specifically designed for vaginal administration in wome

About Solutions

• Pharmaceutical form consists of active drug in water or solvent
• When a solution is applied orally, its a gargle.
• Solutions are given as drops through the eyes, nose, or ears in ampoules for parenteral (injection) use
• Injectable Solutions are Sterile solutions, with specialized injection methods used in the body, called Flakon for example

Solution Types

• A liquid dosage form prepared by dissolving the drug in water or another solvent are solutions
• Small-volume solutions used externally for the eyes ears, or nose are called drops

Suspension

• Solid + liquid = suspension
• A liquid dosage form in which solid drug particles do not fully dissolve but remain dispersed in a liquide
• Because suspension settles over time (so it must be shaken before use
• It also needs to be kept in the refrigerator and because once diluted has shelf life of 15 days

Injections

• Injections are sterile solutions or suspensions in a water- or oil-based medium that are designed for subcutaneous (under the skin) or intramuscular
• Some ways administering include (into the muscle) administration through either sealed glass ampoules or airtight rubber-capped vials

Ampoules

• Sealed glass containers that is broken open just before injection and only has a single dose of medication

Vials (Flacon)

• Rubber-capped glass container from which the drug is drawn into a syringe that can be single-dose or multi-dose

What is are some similar liquid drugs?

• Liquid drug formulations that is specifically used for the eye are called eye drops
• Liquid drug formulations that is specifically used for the ear are called ear drops

Emulsion

• Emulsion is a liquid dosage form consisting of two immiscible liquid phases, where one liquid is dispersed as small droplets within the other
• Elixir is a sweetened solution containing alcohol and water, used as a vehicle for medicinal substances

Syrup

• A liquid dosage form with a high concentration of sugar
• The high sugar content prevents the growth of bacteria and molds

Enemas

• Solutions applied rectally that relieve constipation and cleanse the intestines before a medical examination or procedure

Ointment

• Externally used preparations prepared by mixing active ingredients with bases such as vaseline and lanolin
• Preparations contain more water (water-based) than ointments.

Gels

• Transparent or translucent semi- solid preparations in which the drug is dispersed in a gel base

Transdermal Therapeutic System

• These systems deliver a substance through the skin, like a nicotine patch, or alzheimer medication
• This is special system that allows the drug to be absorbed through the skin and pass into the bloodstream and is a form of a band and provides long-term and controlled drug release

Gas Dosage Forms

• Medicines that are gases or volatile liquids can be administered by inhalation using a mouthpiece, face, mask, hood or endotracheal tube.
• Inhalers are devices that sends medication directly to the lungs in fine powder or vapor form and are usually used for respiratory diseases
• Nebulizer converts liquid medications into a fine vapor and deliver them to the lungs by inhalation