General Pharmacology_General Considerations

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General Aspects of Pharmacology:

General Aspects of Pharmacology Prof. R. K. Dixit Pharmacology and Therapeutics K. G. M. U. Lucknow [email protected]


Terminologies Pharmacology - Study of Drugs (Pharmacon- Drug, Logos- Knowledge) Drug- Any substance used for diagnosis, prevention and treatment of diseases (also prevention of pregnancy) Clinical Pharmacology- Study of drugs on humans Preclinical Pharmacology- Study of drugs on animals Pharmacy- Preparation and dispensing of medication


Pharmacotherapeutics- Use of drug for treatment of diseases (The action of drug occurs on the body cells only, modify the functions of body cells) Chemotherapeutics- Use of drugs for treatment of parasites as well as cancer Pharmacodynamic agents- Drugs modify functions of body cells of patient without producing any new effect Chemotherapeutic agents- Drugs selectively act against foreign parasites as well as cancer cells Pharmacognosy- The branch of pharmacology which deals with identification of sources of drugs Toxicology- Branch which deals with the overdoses of drugs (or Poisons) Terminologies

Sources of Drug Information:

Sources of Drug Information Pharmacology textbooks for medical, dental and nursing Drug reference guides Current medical and dental journals Pharmacology reference books Goodman and Gilman: The Pharmacologic Basis of Therapeutics Physician’s Desk Reference Drug Facts and Comparison Pharmacopeia Handbook of Nonprescription Drugs PDR for Herbal Medicine Physician's Desk Reference (PDR)- Contains descriptions (package inserts) using FDA standards, Package Inserts : Include a description, indications, precautions, dosage, and contraindications.   Electronic databases and Internet

Drug Names:

Drug Names Chemical Name – Determined by the chemical structure of the drug (Not used by clinicians, Of importance in pharmaceutics) Trade Name – Registered as a trademark under the Federal Trademark Law; usually chosen because it can easily be remembered and promoted commercially Generic Name – Official name of the drug (Same throughout world Note- Usually same drug prescribed by generic name is cheaper than prescribed by trade name.

Generic Names :

Generic Names Most often classes of drugs have the same generic “last” name “Prils”— ACE inhibitors “Sartans”— ARBs (angiotensin receptor blockers) “Triptans”— treatment of acute migraine headache “Statins”— Lower LDL-cholesterol “Dipines”— calcium channel blockers “Tidines”— H2 blockers reduce nighttime acid “Prazoles”— Proton Pump Inhibitors, GERD “Azoles”— antifungal


Chemical Name 7-chloro-1, 3-dihydro-1, methyl-5-phenyl-2h-1 Generic Name diazepam Official Name diazepam, USP Brand Name Valium ® Names of Drugs


Equivalents Chemically Equivalent – Two formulations of a drug meet established chemical and physical standards Biologically Equivalent – Two formulations produce similar concentrations in blood and tissues Therapeutically Equivalent – Equal therapeutic effects during a clinical trial

Drug Regulatory Laws:

Drug Regulatory Laws Drug Legislation The Food and Drug Act of 1906 Harrison Narcotic Act of 1914 Food, Drug, and Cosmetic Act of 1938 Durham-Humphrey Law of 1952 Kefauver-Harris Bill (1962) Controlled Substance Act of 1970 Omnibus Budget Reconciliation Act of 1990 Drug and Cosmetic Act India 1945

Talking to each other in Cells:

Talking to each other in Cells Three distinct languages Nervous system Neurotransmitters Endocrine system Hormones Immune system Cytokines (Inflammatory mediators) In disease, all systems are affected The three systems can’t exist without each other The actions of one impact the actions of the others I.e., stress (nervous system) disrupts endocrine system which may respond with glucocorticoid production = suppressed immune response

Drug Classes:

Drug Classes On basis of Chemical structure Body system affecting Action of agent Mechanism of actions Indications

Drug forms :

Drug forms Liquid: (solute - solvent) – Solution Tinctures: drug extracted chemically with alcohol. Suspensions – liquid preparations don’t remain mixed Spirits: Volatile chemicals dissolved in alcohol Gaseous - Nitrous oxide, Oxygen Emulsions: oily substance mixed with a solvent that won’t dissolve it. (oil and vinegar). Elixirs: Drug in an alcohol solvent. Syrups: Drug dissolved in sugar and water (cough syrup). Solids: capsule, tablet, lozenge, powder Topical use: ointment, paste, cream, aerosol

Drug storage:

Drug storage Properties may be altered by environment. Temperature Light Moisture Shelf-life

Drug response relationship:

Drug response relationship Plasma level profiles Length of onset, duration, termination of action, minimum effective concentration and toxic levels Onset of action A medication reaches it’s minimum effective concentration Minimum effective concentration Level of drug needed to cause a given effect Duration of action How long the drug remains above it’s minimum effective concentration Termination of action Time from when a drug drops below minimum effective concentration until it’s eliminated Therapeutic index Ratio of a drug’s lethal dose for 50% of population to its effective dose for 50% of population Half-life Time the body takes to clear one half of the drug (Five half lives required to eliminate)


Synergism Two drugs that have the same effect are given together and produce a response greater than the sum of their individual responses Potentiation One drug enhances the effect of another Interference One drug affects the pharmacology of another drug Antagonism The opposition between 2 or more medications ex. narcotics and Naloxone Bolus A single, often large dose of a drug. Often the initial dose Cumulative action An increased effect caused by multiple doses of the same drug. Caused by buildup in the blood.


Hypersensitivity A reaction to a drug that is more profound than expected and which often results in an exaggerated immune response Idiosyncrasy A reaction to a drug that is significantly different from what is expected Indication The medical condition for which the drug has proven therapeutic value Parenteral Any route of administration other than the digestive tract Pharmacodynamics Study of the mechanisms by which drugs act to produce biochemical or physiological changes in the body Pharmacokinetics Study of how drugs enter the body, reach their site of action and are eliminated from the body


Potentiation The enhancement of a drug’s effect by another drug Eg. promethazine may enhance the effect of morphine; also alcohol and barbiturates Refractory The failure of a patient to respond as expected to a certain medication Synergism The combined action of 2 or more drugs that is greater than the sum of the 2 drugs acting independently Therapeutic Action The intended action of a drug given in an appropriate medical setting Therapeutic Threshold The minimum amount of a drug that is required to cause the desired response Therapeutic Index The difference between the therapeutic threshold and the amount of the drug considered to be toxic Often referred to as Safe and Effective range


Tolerance The decreased sensitivity or response to a drug that occurs after repeated doses Increased doses are required to achieve the desired effect Untoward Effect A side effect of a drug that is harmful to the patient

Medication Names:

Medication Names Prescription medications Over-the-counter (OTC) medications Street drugs Herbal medications Enhancement drugs Vitamin supplements

Medication Forms:

Medication Forms Form of medication usually dictates route of administration. Manufacturer chooses the form to ensure: Proper route of administration Timing of its release into the bloodstream Effects on the target organs or body systems

Medication Forms :

Medication Forms Forms Tablets and capsules Solutions and suspensions Metered-dose inhalers Topical medications Transcutaneous medications Gels Gases for inhalation

Tablets and Capsules:

Tablets and Capsules Capsules are gelatin shells filled with powdered or liquid medication. Tablets often contain other materials that are mixed with the medication and compressed.

Solutions and Suspensions :

Solutions and Suspensions Solution is liquid mixture of substances. Mixture will not separate by filtering or letting it stand. Example: nitroglycerin spray Suspension is substance that does not dissolve well in liquids. Will separate if it stands or is filtered

Metered-Dose Inhalers (MDI):

Metered-Dose Inhalers (MDI) Liquids or solids broken into small enough droplets or particles may be inhaled. Metered-dose inhaler (MDI) directs such substances through mouth into lungs. Delivers same amount each time.

Topical Medications:

Topical Medications Include lotions, creams, ointments Applied to skin surface and only affect that area Examples Lotion: Calamine lotion Cream: hydrocortisone cream Ointment: Neosporin ointment

Transcutaneous Medications :

Transcutaneous Medications Also referred to as trans-dermal Designed to be absorbed through skin Many have systemic effects. Examples: Nitroglycerin paste Adhesive patch


Gels Semiliquid Administered in capsules or through plastic tubes Example: oral glucose for patient with diabetes

Forms of Medication:

Forms of Medication

Drug Sources:

Drug Sources

Sources of Medication:

Sources of Medication Synthetic Made completely in a laboratory Semisynthetic Made from chemicals derived from plant, animal, or mineral sources


Some medications are used “ off-label. ” A purpose not approved by the FDA At doses different from the recommended doses By a route of administration not approved by the FDA

Factors Affecting Response to Medications:

Factors Affecting Response to Medications Age Percentage of body fat Lowest in infants; increases in adults Percentage of body water Highest in newborns; decreases throughout life Percentage of body proteins Varies throughout life span Consider titration of medication for pediatric or elderly patient. Alteration of metabolism/elimination may prolong effects. Patients at extremes of age are disproportionately prone to paradoxical medication reactions.

Factors Affecting Response to Medications:

Factors Affecting Response to Medications Weight-based medication dosing Quantity of medication is multiplied by the patient ’ s weight in kilograms. Advantages: Amount of medication is proportional to size of patient Manufacturers have already calculated factors. Can calculate appropriate dose for all ages Limitations: Need patient ’ s weight in kilograms Does not consider alterations in distribution, metabolism, and elimination Some medications are intended to be based on the patient ’ s ideal body weight.

Factors Affecting Response to Medications:

Factors Affecting Response to Medications Environment Hyperthermia May increase metabolism of drugs May reduce amount of drug returned to circulation Hypothermia Impairs effectiveness of medications used in traditional cardiac life support

Factors Affecting Response to Medications:

Factors Affecting Response to Medications Genetic factors Be careful when administering medications to patients with genetic disorders. Primary pulmonary hypertension Sickle cell disease Glucose-6-phosphate dehydrogenase deficiency Patients and family are good sources of information.

Factors Affecting Response to Medications:

Factors Affecting Response to Medications Pregnancy Many changes take place in the body: Cardiac output and intravascular volume increase. Hematocrit decreases. Respiratory tidal volume, minute volumes increase. Inspiratory/expiratory reserve volumes decrease. Gastrointestinal motility decreases. Renal blood flow and urinary elimination increase. Endocrine glands undergo change.

Factors Affecting Response to Medications:

Factors Affecting Response to Medications Psychosocial factors Pain, anxiety, and discomfort can vary among individual patients. Be alert for verbal and nonverbal cues. Medication administration is complicated by the placebo effect.

Types of Medication Responses:

Types of Medication Responses Therapeutic (desired) effects Medication is selected based on patient ’ s: Illness, injury, complaint, signs, symptoms Condition should match “ Use/Indication ” listed on the medication profile. Medication is administered in a dose intended to produce a desired clinical response. Some require repeated dosing. Capable of demonstrating cumulative action

Types of Medication Responses:

Types of Medication Responses Adverse medication effects Clinical changes that are not desired and cause harm or discomfort to the patient Consider in relation to the patient ’ s condition Patients with chronic medical conditions are more susceptible. Patients may be unable to tolerate even mild adverse effects. May range in severity Can be desirable in certain situations and harmful in others Can be completely unexpected Idiosyncratic medication reactions (Genetically determined)

Categories of Pharmacology:

Categories of Pharmacology Pharmacognosy – study of characteristics of natural drugs and their sources Pharmacodynamics – study of what drugs do to the body Pharmacokinetics – what the body does to drugs Pharmacotherapeutics – study of how drugs are used to treat disease Toxicology – study of poisonous effects of drug

Food and Drug Administration (FDA):

Food and Drug Administration (FDA) An agency of the Department of Health and Human Services. Regulates the manufacture and distribution of every drug used in the U.S. Requires drug manufacturers to perform clinical tests on new drugs before the drugs are used by humans. Manufacturer must continue to demonstrate the drug’s safety and efficacy. FDA can withdraw a drug from the market at any time if evidence suggests that it is no longer safe or effective.

Pharmacotherapeutics – Safety and Efficacy :

Pharmacotherapeutics – Safety and Efficacy When a patient complains a drug is not working, it may be due to any of the following: Patient does not understand how the drug works Dosage needs to be adjusted Therapeutic level has not been reached Wrong drug was prescribed Some drugs work better with one patient than another Some forms of drugs work better The trade name drug may work even if the generic does not

Pharmacotherapeutics – Kinds of Therapy:

Pharmacotherapeutics – Kinds of Therapy Acute – improve life threatening or serious condition Empiric – give until other tests prove another therapy is appropriate Maintenance – maintain a condition Palliative – reduce the severity of a condition or pain Prophylactic – prevent a disease or condition Replacement – provide chemicals missing by the patient Supportive – for condition other than primary disease Supplemental – avoid deficiency

Writing Prescriptions:

Writing Prescriptions Four basic parts: Superscription Inscription Subscription Signature

Patient Education About Over The Counter (OTC) Drugs:

Patient Education About Over The Counter (OTC) Drugs You need to give your attention to all the drugs a patient is taking whether prescription or OTC Caution patient not to treat themselves with OTC drugs Inform patient that many OTC medications contain more than one active ingredient. Tell the patient that interactions can occur when a person takes more than one OTC at a time or takes one with prescription drugs

Patient Education About Drugs – Prescription Drugs:

Patient Education About Drugs – Prescription Drugs Inform patient about special considerations and drug safety precautions Encourage: Complete medication list Complete adverse reactions list Patient compliance


Greek words: • pharmakon - drug or medicine • logos - the truth about or a rational discussion Birth of Experimental Pharmacology is associated with Francois Magendie in the early 19th century. He discovered how Strychnine and Curare worked. What is Pharmacology?


Pharmacologists Study Science at Every Level


Subdivisions of Pharmacology Molecular Pharmacology: study of the biochemical and biophysical characteristics of interactions between drug molecules and those of the cell Example: Drug-Receptor Interaction Biochemical Pharmacology: study of how drugs act with and influence the chemical ‘machinery’ of the organism Example: signal transduction through G proteins


Subdivisions of Pharmacology Behavioral Pharmacology: study of the effects of drugs on behavior Example: treatment of Attention Deficit Disorders Endocrine Pharmacology: study of drugs that are hormones or hormone derivatives Example: creation of The Pill Clinical Pharmacology: application of pharmacodynamics and pharmacokinetics to patients with disease. Example: use of pharmacogenomics to tailor individual medical treatment Chemotherapy: study of drugs used for treatment of microbial/viral infection and malignancies Example: treatment of cancer through anti-angiogenic agents such as bevacizumab. ANTIBODY THERAPY Systems and Integrated Pharmacology: study of the use of whole animal approaches to best predict the efficacy of new treatments in the human. Example: use of pharmacogenomics to tailor individual medical treatment Veterinary Pharmacology: study of the use of drugs for disease and health problems unique to animals. Example: treatment of feline leukemia (Viral) with Acemannan


Pharmacy This is a separate profession responsible for the preparation and dispensation of medication. Pharmaceutical Science Pharmacology is NOT…


Examples of Questions that Pharmacologists Ask: How do drugs act at cell surfaces to alter processes inside cells? How can drugs help us unravel the mechanisms of biochemical and physiological processes? Pathophysiological processes? Example: How does the compound fenfluramine activate serotonin receptors (to cause valvulopathy??) Example: Why do endothelin receptor antagonists reduce blood pressure? Is endothelin involved in this disease? How can knowledge of the structure of a macromolecule be used to design (intelligently) new more effective drugs? How do organisms develop increased or decreased sensitivity to drugs? Example: Can HIV proteins be targeted with specific Inhibitory molecules? Can we predict protein mutation? Example: Resistant strains of streptomyocin, tumor resistance to chemotherapy.


Examples of Questions that Pharmacologists Ask:


Why Read Pharmacology?... Synthesis of many biomedical sciences and necessarily integrative. Diverse, diverse, diverse! Pharmacology has been one of the greatest medical successes of the 20th century, yet is is vastly misunderstood. Pharmacology readily translates into improved human health. Trained to use drugs experimentally and clinically appropriately …It’s absolutely exciting!


Pharmacology is integrated into your daily life: Antibiotics Aspirin a day to reduce risk of myocardial infarction The birth control pill When you get sick, you assume the medication will be there. Who develops these medications??? PHARMACOLOGISTS!!


Drugs are chemicals used to diagnose, treat, and prevent disease.


Pharmacology is the study of drugs and their actions on the body.

Components of a Drug Profile:

Components of a Drug Profile Name Classification Mechanism of Action Indications Pharmacokinetics Side Effects Routes of Administration Contraindications Dosage How Supplied Special Considerations

Drug Forms :

Drug Forms Solid Forms: Such as pills, powders, suppositories, capsules. Liquid Forms: Such as solutions, tinctures, suspensions, emulsions, spirits, elixirs, syrups.

Solid Forms:

Solid Forms Pills —drugs shaped spherically to be swallowed. Powders —not as popular as they once were. Tablets —powders compressed into disk-like form. Suppositories —drugs mixed with a wax like base that melts at body temperature. Capsules —gelatin containers filled with powders or tiny pills.

Liquid Forms:

Liquid Forms Solutions —water or oil-based. Tinctures —prepared using an alcohol extraction process. Suspensions —preparations in which the solid does not dissolve in the solvent. Emulsions —suspensions with an oily substance in the solvent.

Liquid Forms:

Liquid Forms Spirits —solution of a volatile drug in alcohol. Elixirs —alcohol and water solvent; often with flavoring. Syrups —sugar, water, and drug solutions.

Responses to Drug Administration :

Responses to Drug Administration Side Effect —unintended response to a drug. Allergic Reaction —hypersensitivity. Idiosyncrasy —drug effect unique to an individual.

Responses to Drug Administration :

Responses to Drug Administration Tolerance —decreased response to the same amount. Cross Tolerance —tolerance for a drug that develops after administration of a different drug. Tachyphylaxis —rapidly occurring tolerance to a drug.

Responses to Drug Administration :

Responses to Drug Administration Cumulative effect —increased effectiveness when a drug is given in several doses. Drug dependence —the patient becomes accustomed to the drug’s presence in his body. Drug interaction —the effects of one drug alter the response to another drug. Drug antagonism —the effects of one drug block the response to another drug.

Responses to Drug Administration:

Responses to Drug Administration Summation— additive effect, two drugs with the same effect are given together — similar to 1+1=2. Synergism— produce a response greater than the sum of their individual responses — similar to 1+2=3.

Responses to Drug Administration :

Responses to Drug Administration Potentiation —one drug enhances the effect of another. Interference —the direct biochemical interaction between two drugs; one drug affects the pharmacology of another drug.

Drug Interactions:

Drug Interactions Drug interactions occur whenever two or more drugs are available in the same patient. The interaction can increase, decrease, or have no effect on their combined actions.

Common abbreviations:

Common abbreviations PO IM IV SL Sub q AC Ad lib bid, tid, qid HS PC PRN Stat cc g Gr gtt mL oz Tsp tbsp

General Principles of Drug Therapy:

General Principles of Drug Therapy Expected benefits should outweigh potential adverse effects Drug therapy should be individualized Drug effects on quality of life should be considered in designing a drug therapy regiment Use as few drugs as possible Fixed dose combinations increase compliance Lowest dose with therapeutic effect Follow guidelines but dosages must be individualized Drugs with long half-lives may require loading doses then titrated lower maintenance doses


Pharmacogenetics Area of pharmacology concerned with unusual responses to drugs caused by genetic differences between individuals. Responses that are not found in the general population, such as general toxic effects, allergies, or side effects, but due to an inherited trait that produces a diminished or enhanced response to a drug. Differences in Enzyme Activity Acetylation polymorphism Butylcholinesterase alterations Cytochrome P450 aberration


Drugs Drugs, as well as hormones, neurotransmitter, autocoids and toxins can make possible the transfer of information to cells by interaction with specific receptive molecules called “receptors”. Receptor DRUG


Drugs Drugs interact with biological systems in ways that mimic, resemble or otherwise affect the natural chemicals of the body. Drugs can produce effects by virtue of their Acidic or basic properties (e.g. antacids, protamine), Surfactant properties (amphotericin), Ability to denature proteins (astringents), Osmotic properties (laxatives, diuretics), or Physicochemical interactions with membrane lipids (general and local anesthetics).

Drug Approval Process:

Drug Approval Process Pre-clinical testing on cells an animals Clinical testing in (4) phases I – small # of healthy people II – small # of people with the disease III – large # of people with the disease (marketing can occur after phase III) (new expedited process allows after phase II) IV – post marketing; voluntary

Molecular pharmacology ::

Molecular pharmacology : Molecular pharmacology is concerned with studies of basic mechanisms of drug actions on biological systems. The idea that drugs act upon specific sites (receptive substance) began with John New Port Langley (1852-1926) of Cambridge. However the word ‘receptor’ is given by Paul Ehrlich (1854- 19 15). The receptor concept which forms a key note in the development of molecular pharmacology became firmly established by the quantitative work of Alfred Joseph Clark (1885-1941), a professor of pharmacology at Kings College London.


Medicines usually contain other substances (excipients, stabilisers, solvents, etc.) besides the active drug, to make them more convenient to use. To count as a drug, the substance must be administered as such, rather than released by physiological mechanisms. Many substances, such as insulin or thyroxine, are endogenous hormones but are also drugs when they are administered intentionally.

Medications safely can be given only when:

Medications safely can be given only when Know: Indications Contraindications Precautions Practice proper technique (Selection of Correct Dosage form and Route of administration) Take careful drug histories Observe & document

Rights of medication administration!:

Rights of medication administration! Right Diagnosis and Diseased Person Drug Dose Duration, Frequency and Timing (Diurnal variations) Dosage formulations and Route Documentation Discontinuation and Denial or Refusal or Referral Determine right cost of therapy (appropriate according to financial status of patient) Discuss in details with patients and relatives regarding diseases and drugs Disease status of patient Drug – Drug Interactions and Drug-Food Interactions



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