Pharmacology

1. Pharmacology-I
Course code PMS-614
By Dr. Junaid Athar
Chapter No. 1
Institute of paramedical sciences,
Khyber Medical University Peshawar
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2. Introduction to Pharmacology
Def: Study of substances that interact with living system through chemical process,
especially by binding to regulatory molecules and activating or inhibiting normal
body process.
• Pharmacology is derived from two words; Pharmacon means drugs or medicine
and logos means study
• It has two devisions as follows
• Pharmacokinetics: it means the movement of drugs in the body (absorption,
distribution, biotransformation, and excretion).
• Pharmacodynamics: The mechanism by which the drug exerts its effect. For
example, how aspirin work as analgesic.
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3. Basic definitions
Drug means any chemical substance which exerts a physiological effect on the cell.
Medicine, means any drug substance used to prevent, treat, cure, or diagnose a disease
in proper dose. All medicines are drugs, not all drugs are medicines.
Therapeutics: the branch of medicine that deals with the treatment and cure of diseases
Toxicology: Toxicology is the study of the harmful effects of chemicals and biological
substances on human health
Adverse reaction : A response to a drug which is noxious and unintended
Dose means the amount of medicine taken by a patient
Dosage form means the physical form of the medicines (solids, liquids, gas etc.)
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4. 4

5. Cont…
• Over the counter (OTC) medicine means those medicines for which the
physician prescription is not required. For examples, analgesics.
• Orphan drug: A drug used to treat, prevent, or diagnose an orphan disease. An
orphan disease is a rare disease or condition that affects fewer than people. Less
than 200000 in USA, less than 20000 in Europe.
• Analgesic means those medicines which are used for pain
• Antipyretics means those drugs which are used for fever
• Drug source: it means the origin of drug (natural, semi synthetic, synthetic etc.
natural sources of drug are plants, minerals, animals, and microbes).
• Drug nomenclature: Each drug actually has 3 names. The first is the chemical
name. The second name is the generic. The 3rd name is used by the pharmaceutical
companies. 5

6. Cont…
• Idiosyncratic means unexpected drug reaction
• Teratogenic means harmful effects of drugs on the fetus
• Synergism means when the combination of drugs increases the effects
• Antagonism means when the combination of drugs decreases the effects
• Active ingredient means biologically active substance which produce
effect
• Efficacy means maximum effect that a drug can produce regardless of dose.
• Potency means amount of a drug that is needed to produce a given effect
• Pharmacopoeia: it is a source of drug information. it is an official
publication, containing a list of medicinal drugs with their effects and
directions for their use. BP: British Pharmacopoeia. USP: United States
Pharmacopeia 6

7. 7

8. Cont…
• Bioavailability is the degree to which or the proportion of the drug that is
available to the site of action or target tissue to produce the desired effect.
• Half-life (t1/2) is the time taken by the plasma concentration of the drug to
decrease by 50%, or reach half of the original concentration
• Prophylactic agent is any drug that prevents a disease or illness from occurring
• Therapeutic effect : A drug is given to produce a desired effect on the body,
either to treat a disease or to relieve symptoms. This is referred to as a drug’s
therapeutic effect.
• Tolerance is a decrease in the pharmacological response to a drug that occurs with
continued administration
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9. ADVERSE DRUG REACTION
Any noxious change which is
Suspected to be due to a drug
At doses normally used in man
May requires treatment or decrease in dose or
Caution in the future use of the same drug
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10. Continued…
• Incidence of ADR are more in
• Polypharmacy
• Elderly
• Children
• Patient with multiple diseases
• Pregnancy
• Malnourished
• Immunosuppression
• Drug Abusers and addicts
• Develop
• Immediately
or
• Prolonged medication
or
• After stopping. 10

11. GRADING OF SEVERITY OF ADVERSE DRUG
REACTIONS :
Minor : No therapy, antidote or prolongation of
hospitalization is required.
Moderate: Requires change in drug therapy, specific
treatment or prolongs hospital stay.
Severe: Potentially life-threatening, causes permanent
damage or requires intensive medical treatment.
Lethal : Directly or indirectly contributes to death of the
patient. 11

12. CLASSIFICATIONS OF ADR
• A (Augmented)
• B (Bizarre)
• C (Continuous)
• D (Delayed)
• E (Ending Use)
• F (Failure of Efficacy)
• Broadly
• Type- A (Predictable)- Based on pharmacological properties
• Type- B (Non-predictable) – Based on Immunological response
and genetic makeup of person 12

13. TYPE A- AUGMENTED
• These are based on the pharmacological properties of the drug so can be predicted.
• They are common and account for 75% of ADRs
• Dose related and preventable mostly reversible.
Examples:-
• Anticoagulants (e.g., warfarin, heparin) – bleeding
• Anti-hypertensives (e.g.. α1-antagonists) – hypotension
• Anti-diabetics (e.g. insulin) - hypoglycemia
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14. TYPE B- BIZZARE OR UNPREDICTABLE
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• Have no direct relationship to the dose of the drug or the pharmacological
mechanism of drug action.
• Develop on the basis of:
• Immunological reaction on a drug (Allergy)
• Genetic predisposition (Idiosyncratic reactions)
• More serious clinical outcomes with higher mortality and morbidity.
• Mostly require immediate withdrawal of the drug.

15. TYPE C – CHRONIC (CONTINOUS) USE
• They are mostly associated with cumulative-long term exposure
Example:-aspirin ibuprofen naproxen
Analgesic (NSAID)– interstitial nephritis, papillary sclerosis, necrosis
TYPE D – DELAYED
• They manifest themselves with significant delay
imminomodulatory
• Teratogenesis -Thalidomide – Phocomelia (flipper-like fore limbs)
• Mutagenesis/Cancerogenesis
Others:
Tardive dyskinesia – during L-DOPA Parkinson disease treatment
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16. TYPE E – END OF USE
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• Drug withdrawal syndromes and rebound phenomenons
• Example – sudden withdrawal of long term therapy with -blockers
can induce rebound tachycardia and hypertension

17. PREVENTION OF ADVERSE EFFECTS TO DRUGS
• Avoid inappropriate use of drugs .
• Appropriate drug administration (Rational Therapeutics)
• Dose
• Dosage form
• Duration
• Route
• Frequency
• Technique
• Ask for previous history of drug reactions and allergies
• Always suspect ADR when new symptom arises after initiation of treatment. ( No
new drug for new symptom).
• Ask for laboratory findings like serum creatinine etc.
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18. Classification of drugs
•What is drug classification?
• A drug class is a set of medications that have either similar chemical structures,
the same mechanism of action or are used to treat the same disease.
• Drugs have been classified either on the basis;
Chemical composition: β-lactam antibiotic, Benzodiazepine, Steroids
bacterial infection
pencellin anxity
insomnia
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19. Classification based on mechanism of action
• Angiotensin II receptor antagonist: losartan, valsartan
• ACE inhibitor: captopril, ramipril, lisinopril
• Alpha-adrenergic agonist: Phenylephrine, Clonidine
• Beta blockers: Propranolol, Atenolol
• Dopamine agonist:
• Cyclooxygenase inhibitors
• Proton-pump inhibitor: omeprazole, esomeprazole
• Cholinergic:
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20. Classification based on Therapeutic class
• Analgesics: Drug used to relieve pain.
• Antibiotic:
• Anticoagulant
• Antidepressant
• Anticancer
• Antiepileptic
• Antipsychotic
• Antiviral
• Sedative
• Antidiabetic
• Cardiovascular
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21. Contiued…
• An anesthetic or anaesthetic is a drug used to induce anesthesia - in other words,
to result in a temporary loss of sensation or awareness.
• Analgesics: Drug used to relieve pain
• Anthelmintics: a group of antiparasitic drugs that expel parasitic worms
(helminths) and other internal parasites from the body
• An antidote is a drug, chelating substance, or a chemical that counteracts
(neutralizes) the effects of another drug or a poison
• Antimicrobial: these drugs act either to inhibit, kill or retard the growth of
micro-organism
• Anti-inflammatory : the substance or treatment that reduces inflammation or
swelling.
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22. Continued…
• Anticoagulants: these are commonly referred to as blood thinners, are chemical
substances that prevent or reduce coagulation of blood, prolonging the clotting
time.
• Antihistamine: A drug or other compound that inhibits the physiological effects
of histamine, used especially in the treatment of allergies.
• Antacids: An antacid is a substance which neutralizes stomach acidity and is used
to relieve heartburn, indigestion or an upset stomach.
• Anticonvulsants : they are a diverse group of pharmacological agents used in the
treatment of epileptic seizures
• Anti-diarrhoeal: these drugs are used for diarrhea
• Antitussive: Antitussives are medicines that suppress coughing, also known as
cough suppressants.
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23. Continued…
• Anti asthmatics: Drug which provide symptomatic relief of asthmatic attack by
relaxing the smooth muscle of the bronchioles
• Androgens: An androgen is any natural or synthetic steroid hormone which
regulates the development and maintenance of male characteristics
• Antiseptic: Antiseptics are antimicrobial substances which inhibit the growth
of micro organism
• Anti fungal/ antimycotic : It is a pharmaceutical fungicide or fungistatic used to
treat and prevent growth of fungal infection.
• Antispasmodic: An antispasmodic is a pharmaceutical drug or other agent that
suppresses muscle spasms
• Antiemetic: An antiemetic is a drug that is effective against vomiting and nausea.
• Anti tubercular: Specific drug is used in treatment of Tuberculosis (TB) 23

24. Continued…
• Antirheumatic: Drug is used to teat rheumatism
• Bronchodilators: A bronchodilator is a substance that dilates the bronchi and
bronchioles, decreasing resistance in the respiratory airway and increasing airflow
to the lungs.
• Coagulants: An agent that produces coagulation (Coagulation is a complex
process by which blood forms clots).
• Carminatives: A carminative is a herb or preparation intended to either prevent
formation of gas in the gastrointestinal tract or facilitate the expulsion of said gas,
thereby combatting flatulence.
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25. Legal classification
• For the UK legal classification, see Drugs controlled by the UK Misuse of Drugs
Act
• For the US legal classification, see Controlled Substances Act § Schedules of
controlled substances
• Pregnancy category is defined using a variety of systems by different jurisdiction
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26. Any Question?

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