lecture of pharmacology Department of Community health Technologies

1. Lecture 1& 2: General Considerations
by :- Dr. Raghda Saad mohammed
Pharmacolog
y

2. General Considerations
Pharmacology
Which is the science that studies the physical and chemical properties of compounds and
biochemical and physiological effect of drugs on the body , mechanism of action , and also
study pharmacokinetics and pharmacodynamics .
Drug :- Is any chemical substance except food that affect living processes and it is used
to maintain human or animal health .
Pharmacology is divided into ; -
 A. Pharmacodynamics :- Investigation of how drugs , alone and in combination , affect the
body [ young , old , well , sick ] .
 B. Pharmacokinetics ;- The effect and reaction of living tissue on the drug absorption ,
distribution , metabolism , excretion , or how the body, Well or sick affects drugs .

3. Pharmacokinetics
 There are four major processes .
Drug absorption .
Drug distribution.
Drug metabolism.
Drug excretion.

4. 1.Absorption
 It is the movement of a drug from its site of administration to the target site.
 Factors affecting drug absorption;
 a. Rate of dissolution: Before absorption the drug must be soluble.
 b. Surface area: Organ or tissue surface area related to drug absorption, large
surface area lead to quick absorption rat.
 C. Blood flow; - areas with quick blood flow lead to quick absorption rat.
 d. Lipid solubility
 e. PH.
 f. Presence of ingesta
 g. Rate of passage of ingesta.
 i. Vehicle.

5. 2. Distribution
 It is the movement of drugs throughout the body .
 Practically all drugs must enter cells to undergo metabolism and excretion .
 After distribution in blood circulation the drug go to storage depots , .which
are ;-
 [1]-Plasma protein.
 [2]-Cellular tissue.
 [3]-Fatty tissue .

6. 3. Metabolism
 Also known as [biotransformation], it is defined as the enzymatic alteration of drug structure,
or it is a chemical changes in Drug molecule after absorption. Most drug metabolism takes
place in the liver.
 Site of metabolism ;- Liver, kidney, plasma, lung and skin.
 Metabolism Pathways
 [1]-Oxidation
 [2]-Reduction
 [3]-Conjugation
 [4]-Hydrolysis

7. 4. Excretion
It is the removal of drugs outside of the body. Drugs
and their metabolites , can exit the body in urine,
bile, sweat, saliva, breast milk, and expired air
.The most important organ for drug excretion is
the kidney .

8. Prescription
 It is an order from the doctor to give the drug to
the patient. The prescription is consist of ;-
1. Superscription:- include name of the patient,
Age, Address.
2. Inscription
3. Subscription
4. Signature

9. Medication during pregnancy
 Essentially all drugs can cross the placenta. The factors that
determine drug passage across the membranes Of the
placenta are the same factors that determine drug passage
across all other membrane. Drugs that are lipid soluble cross
the placenta easily ,whereas drugs that are ionized, highly
polar, or protein bound cross with difficulty.

10.  Clinician should assume that any drug taken during pregnancy will
reach the fetus. The drugs may cause teratogenesis
 For example when heparin is taken by pregnant woman it can cause
osteoporosis .Regular use of dependence – producing drugs
 [e.g. barbiturates, alcohol, ] during pregnancy can result in the
birth of a drug –dependent infant. Certain pain relievers used during
delivery can depress respiration in the neonate.
 Congenital anomalies have multiple causes, including [genetic,
environmental, chemicals, and drugs.].
 Drugs known to be teratogenic include;- [1]-Warfarin.
[2]Anticancer. [3]Adrenocortical steroids. [4]-Sex –hormones.
 [5]-alcohol.

11. Drug Therapy in Pediatric Patients
 Patients who are very young ,respond differently to drugs than
does the rest of the population. Most differences are quantitative.
 The pediatric population is subdivided into six groups:
1. Premature infant [less than 36 weeks gestational age].
2. Full-term infants [36 to 40 weeks gestational age]
3. Neonates [first 4 postnatal weeks].
4. Infant [weeks 5 to 52 postnatal].
5. Children [1 to 12 years].
6. Adolescents [12 to 16 years ].

12.  The increased sensitivity of infants is due largely to the
immature state of five pharmacokinetic processes:
1. Drug absorption
2. Protein binding of drugs
3. Exclusion of drugs from the central nervous system [
CNS]-by the blood-brain barrier.
4. Hepatic drug metabolism.
5. Renal drug excretion .

13. Drug Therapy in Geriatric Patients
The elderly those 65 years and older;- Medication in
this age group carries a risk because the dosing must
be modified to suit them , older patients are more
sensitive to drug.

14.  Adverse drug reactions (ADRs):- defined by the World
Health Organization( WHO ) is any undesired effects that
occurs at normal drug doses.
 Mild reactions:- drowsiness, nausea, itching, and rash.
 Sever reactions:- include respiratory depression, Anaphylaxis,
hepatocelluler injury, and hemorrhage- all of which can result
in death.

15.  Toxicity:-it is a ADRs caused by excessive dosing. e.g. include coma from
an overdose of morphine and severe Hypoglycemia from an overdose of
insulin.
 Allergic reaction: - It is an immune response. The intensity of allergic
reaction can range from mild itching to severe rash to anaphylaxis.
 Teratogenic Effect:-it is drug induced birth defect. Medicines and other
chemicals.
 Organ - specific toxicity; - Many drugs are toxic to specific organs. e.g.
[amphotericin B, an antifungal drug]-cause injury to the kidney.
[Gentamicin, cause injury to the inner ear
 Hepatotoxic drugs:-Drugs are the leading cause of acute liver failure

16. Drug Interaction
 It can occur whenever a patient takes two or more drugs Interactions are both desired
and undesired.
 Consequences of drug –drug Interaction -: When drug A interacts with drug B
there are 3 Possible outcomes:
 1. Intensification of effects :- When a patient is taking two medication, one drug
may intensify the effects of the other.
 2.Increased therapeutic effects; - The interaction between Sulbactam and
Ampicillin represents a beneficial interaction .When administered alone .Ampicillin
undergoes rapid inactivation by bacterial enzymes. Sulbactam inhibits those
enzymes, and thereby prolongs and intensifies Ampicillin’s therapeutic effects.
 3.Increased Adverse Effects: - The interaction between aspirin and warfarin.
[Undesirable].