This document provides an introduction to pharmacology. It defines key terms like efficacy, potency, therapeutic index, and adverse drug reactions. It describes pharmacokinetic principles such as absorption, distribution, metabolism and elimination of drugs. It also discusses pharmacodynamics concepts like agonists, antagonists, and drug-receptor interactions. The document outlines various drug classifications and therapeutic categories. It discusses routes of drug administration including enteral and parental routes. It also covers topics like drug interactions, drug labeling, and patient records.

1. INTRODUCTION TO PHARMACOLOGY
Syed Yousaf Shah
Assistant Professor
Institute of Nursing
Dow University of Health Sciences
LEARNING OBJECTIVES
1.Describe basic terminologies used in pharmacology such as efficacy, potency, therapeutic index, drug
induced toxicity and adverse effects.
2.Describe the basic pharmacokinetic principles such as absorption, distribution, metabolism and
elimination of drugs.
3.Describe pharmaco-dynamics such as agonist, antagonist and drug receptor interaction
4.References
PHARMACOLOGY
“A branch of medical sciences that study drugs and their action on living organisms”
Efficacy
 In medical terms, efficacy refers to the ability of a product or treatment to provide a beneficial
effect.
Potency
 Potency is the concentration (EC50) or dose (ED50) of a drug required to produce 50% of that
drug’s maximal effect.
DRUG
“Any substance that brings about a change in biologic function through its chemical actions
WHY DO NURSES STUDY PHARMACOLOGY??
“ To safely administer medications and to monitor patients who receive these medications”
GENERAL CLASSIFICATION OF DRUG
 Prescription Drugs
 Official Drugs

2.  OTC Drugs
 Controlled Drugs (Narcotic etc)
 High Alert Medication
e.g Heparin
Therapeutic Classification
 Analgesics
 Anxiolytics
 Anesthetics
 Anti- Asthmatics
 Antiinfectives
 Antibacterials
 Antivirals
 Antifungal
 AntiTuberculer Drug
 Antimalarials
 Antacids
 Antiacne
 Antihypertensives
 Antianginal
 Antiarrythmics
 Antiinflammatory
 Hypolipidemics
 Antiepileptics
 Antiemetics
 Antidiarrheal

3.  Antihistamines
RELATED DEFINITIONS
 Receptor
“A specific protein in either the plasma membrane or interior of a target cell with
which a chemical messenger/drug combines”
 Mechanism of Action
“The ways by which drugs can produce therapeutic effects”
 Dose
“The amount of a drug to be administered at one time”
Pharmacology, Definitions
 Indications
“The reasons for administering a medication or performing a treatment”
 Contra-indications
“Factor that prevents the use of a medication or treatment (e.g., Allergies)”
 Effects (therapeutic effect)
“The desired results of administration of a medication”
 Side Effects (adverse effects)
“Effects that are harmful and undesired, and that occur in addition to the desired therapeutic
effects”.
 Duration
“The time a drug concentration is sufficient to elicit a therapeutic response
 Onset
“The time it takes for the drug to elicit a therapeutic response”

4. SOURCES OF DRUG INFORMATION
 Text books
 Materia medica (sources, nature, properties, and preparation of drugs )
 Pharmacopea (book containing official list of drugs)
 Formulary (list of prescription drugs)
 Journals
 Pharmacists
Drug Nomenclature
 Chemical name - represents the exact description of the drug’s chemical composition
 Generic name (non-proprietary)
- simpler than the chemical name and - derived from the chemical name itself
- easier to remember
 Brand or trade name (proprietary)  is developed by the company requesting approval for the
drug and identifies it as the exclusive property of that company.

5.  Flagyl®
is the trade name for metronidazole.
 Metoclon®
is the trade name for Metoclopramide.
 Amoxil®
is the trade name for amoxycillin.
Pregnancy Categories
 Category A-studies in pregnant women failed to show risk to the fetus.
 Category B- animal studies have failed to show a risk to the fetus but there are no adequate
studies in women.
 Category C-animal studies have shown an adverse effect on the fetus, no adequate human
studies, benefits may outweigh risks.
Pregnancy Categories
 Category D-positive evidence of human fetal risk.
 Category X-animal or human studies have shown fetal abnormalities or toxicity
DRUG BODY INTERACTION

6. AGONIST
“A chemical messenger that binds to a receptor and triggers the cell’s response often refers to a
drug that mimics a normal messenger’s action”.
Drug Receptor Interactions

7. ANTAGONIST
“A molecule that competes for a receptor with a chemical messenger normally present in the body. The
antagonist binds to the receptor but does not trigger the cell’s response”

8. ROUTES OF DRUG ADMINISTERATION
 The possible routes of drug entry into the body may be divided into two classes
 ENTERAL ROUTE
 PARENTERAL ROUTE
ENTERAL ROUTE
 Drug placed directly in the gastrointestinal tract (G.I.T):
Sublingual/ buccal - placed under the tongue or sides of mouth
Oral - swallowed
Rectum - Absorption through the rectum
SUBLINGUAL/BUCCAL
Some drugs are taken as smaller tablets which are held in the mouth or under the tongue.
• Advantages:
1. Rapid absorption
2. Drug stability
3. Avoid first-pass effect
• Disadvantages:
1. inconvenient

9. 2. small doses
3. unpleasant taste of some drugs
ORAL
 This route allows the drug to be absorbed across the membranes of the stomach and/or the
intestinal tract.
 Advantages:
1. Convenient - can be self- administered, pain free, easy to take
2. Absorption - takes place along the whole length of the GI tract
3. Cheap - compared to most other parenteral routes
Disadvantages:
1. Sometimes inefficient - only part of the drug may be absorbed
2. First-pass effect - drugs absorbed orally are initially transported to the liver via the
portal vein
3. Irritation to gastric mucosa - nausea and vomiting
4. Destruction of drugs by gastric acid and digestive juices
5. Effect too slow for emergencies
6. Unpleasant taste of some drugs
7. Unable to use in unconscious patient
RECTAL
 Administering drugs into the rectum to be absorbed by the rectum's blood vessels.
 Advantages
 1. Used in unconscious patients and children
 2. If patient is nauseous or vomiting
 3. Good for drugs affecting the bowel such as laxatives
 Disadvantages
 1. Irritating drugs contraindicated

10.  2. Absorption may be variable
PARENTERAL ROUTE
 Injected directly into the body
1. Intravascular (I.V{intravenous}, I.A{intra-arterial} )- placing a drug directly into the blood
stream.
2. Intramuscular (I.M) - drug injected into skeletal muscle.
1. Subcutaneous (S.C)- Absorption of drugs from the subcutaneous tissues
INTRAVASCULAR
Advantages
 1. First pass metabolism is bypassed
(100% bioavailability)

11.  2.Precise, accurate and almost immediate onset of action .
 3. Large quantities can be given, pain free
Disadvantages
 1. Greater risk of adverse effects
 a. high concentration attained rapidly
 b. risk of embolism
INTRAMUSCULAR
Advantages:
 Very rapid absorption of drugs in aqueous solution
Disadvantages:
 Pain at injection sites for certain drugs

12. SUBCUTANEOUS
 Advantages
 1. Slow and constant absorption .
 2. Absorption is limited by blood flow, affected if circulatory problems exist.
 3. Concurrent administration of vasoconstrictor will slow absorption.
 Disadvantages:
• Not suitable for large volume
• Not for irritant drugs
• Pain, necrosis, tissue sloughing

13. Drug administration cardinal rules
 Wash hands before giving meds
 Read MAR carefully. If ever in doubt, check the original order
 Never give medications you are uncertain of unless you have looked them up or have consulted
with pharmacy
Drug Administration Cardinal Rules
 Never give more than 3cc per IM injection
 Wear gloves with all injections
 Do not give oral meds if patient is vomiting, sedated, NPO or is unconscious
 Follow narcotic protocol for signing out of narcotics
Drug Label
 (1) Drug container labels must include
 (a) the generic name of the drug, strength and dosage form, and
 (b) hospital approved abbreviations and symbols.
 (2) Only hospital pharmacy staff may alter a drug container label.
 (3) Inpatient prescription labels must include
 (a) a unique patient name and identifier,

14.  (b) the generic name of the drug, strength and dosage form,
 (c) parenteral vehicle if applicable, and
 (d) hospital approved abbreviations and symbols.
 (4) The following information must be included on the inpatient prescription label if not
available on the medication administration record:
 (a) the frequency of administration;
 (b) the route of administration or dosage form;
 (c) auxiliary or cautionary statements if applicable;
 (d) the date dispensed.
Returned Drugs
 (1) Unused dispensed drugs must be returned to the hospital pharmacy.
 (2) Previously dispensed drugs must not be re-dispensed unless
 (a) they are returned to the hospital pharmacy in a sealed dosage unit or container as originally
dispensed,
 (b) the labeling is intact and includes a legible drug lot number and expiry date, and
 (c) the integrity of the drug can be verified.
Patient Record
 (1) The registrant must ensure the preparation and maintenance of patient records for each
patient for whom drugs are prepared are complete, accurate and current, except patients
admitted for less than 24 hours to
 (a) surgical day care,
 (b) ambulatory care,
 (c) emergency short-stay, or
 (d) other short-stay diagnostic or treatment units.
 (2) The patient record must include
 (a) the patient’s full name and admission date,
 (b) the hospital number and location,

15.  (c) the patient’s date of birth and gender,
 (d) the attending practitioner’s name,
 (e) the patient’s weight and height if applicable to therapy,
 (f) the patient’s allergies, adverse drug reactions, intolerances, and diagnoses,
 (g) a chronological list of drugs which have been prescribed for the patient since admission to
hospital, or, if admission is prolonged, for a minimum period of two years.
 (h) a list of all current drug orders including
 (i) the drug name,
 (ii) the drug strength,
 (iii) the dosage,
 (iv) the route,
 (v) the dosage form,
 (vi) intravenous diluent if applicable,
 (vii) the directions for use,
(viii) administration time or frequenc
References
o Text book of pharmacology for nurses – J.K Grover – Monica malik
o Lippincott illustrated review of Pharmacology
o Katzung. B. G. Basic and clinical Pharmacology
o J.D tripathy, Essential of Medical Pharmacology