pharmacology introduction

1. Pharmacology
Slide- 1

2. Course objectives
• To study general principles of pharmacology that will
enable the student to use drugs properly and safely in
nursing practice.
• To be familiar with the therapeutic indication, toxic
reactions and contraindications used in clinical practice.
• Drug classes will be discussed with some emphasis on
important representative examples of the most widely
used drugs from each class.

3. General principle of pharmacology
• Pharmacokinetics.
• Pharmacodynamics.
• Routes of drug administration.
• Medication classes and names.
• Prescription and non-prescription drugs.
• Factors modify client’s response to drugs.
• The role of nurse in drug administration.

4. What is Pharmacology:
• Is how drugs and other chemical substances
can interact in the biological system.
• Simply defined as “ the study of drugs”.

5. The role of the nurse in drug
administration:
• By knowing basic pharmacological information's nurses
should be able to appoint these information in the
process of administrating the drug and achieve the
process of healing .
• Administrate the drug to the patient in health care
clinics and hospitals.
• note the toxic effects of high doses.
• Know the routes in which the drug could be given.
• Realize the drug contraindications and drugs given in
pregnancy.

6. What is the drug?
• It is necessary to define the medication and the
drug.
• Drug : a chemical substance capable of alerting
biochemical and physiological processes in the body,
those effects can be desirable (therapeutic) or
undesirable (adverse). They don’t confirm new
actions but simply modify existence action.
• Street drugs, medications , some food and even
some chemicals consider under the term of drug.

7. What is the drug?
• Medication: is the drug that used for a purpose
of restoring dysfunctional or pathologic function
in the body to it desired function or process.
• FDA approved for curing and healing.

8. Pharmacokinetics

9. Pharmacokinetics
• = the actions of the body on the drug, including
absorption, distribution, metabolism and
excretion.
• When a drug enters the body, the body begins
immediately to work on the drug.

10. 1-Absorption
• The rate and efficacy of absorption depend on the route
of drug administration.
• Which is determined primarily by: drug properties
(water or lipid solubility, ionization, etc.) & therapeutic
objectives.
• Ex.…….rapid onset of action or long-term
administration or restriction to a local site.

11. 2-Distribution
• It the process by which a drug reversibly leaves
the blood and enter the interstitium
(extracellular fluid) and/ or the cells of the
tissues .

12. 3- Metabolism
• The liver is the major site for drug metabolism.
• The metabolism of drugs into more polar
metabolites is essential for their elimination
from the body, as well as for termination of
their biological and pharmacological activity.

13. 4-Elimination
• Is the irreversible loss of drug from the body.
• Excretory organs eliminate compounds that
posses polar characteristics (water-soluble)
more efficiently than substances with high lipid
solubility.
• lipid-soluble drugs thus are not readily
eliminated until they are transformed to more
polar compounds.

15. Pharmacokinetics parameters:
• Volume of distribution
• Clearance
• Half-life
• Protien-binding
• Bioavailability

16. Volume of distribution (vd):
• Definition: volume of fluid into which a drug is
dispersed (in which the drug is assumed to be
uniformly distributed).
• Vd may be affected by:
• • Patient's age
• • Patient’s gender
• • Patient’s body composition
• • The presence of disease

17. Volume of distribution (vd):
• In general, a small Vd occurs when:
1. Lipid solubility is low
2. High degree of plasma protein binding
3. Low level of tissue binding
• A high Vd occurs when:
1. Lipid solubility is high
2. Low degree of plasma protein binding
3. High level of tissue binding

18. Clearance
means drug elimination
• Is the main PK parameter describing
elimination.
• Definition: the volume of plasma/fluid that is
cleared from drug (removed from the body per
unit time).

19. Half-Life (t1/2)
• It is the time required to change the amount of
drug in the body by one-half during elimination
(or during a constant infusion).

20. Bioavailability
• The fraction (or percentage) of the administered dose of
drug that reaches the systemic circulation.
• Bioavailability is defined as unity (or 100%) in the
case of intravenous administration. After administration
by other routes, bioavailability is generally reduced by
incomplete absorption first-pass metabolism, and any
distribution into other tissues that occurs before the
drug enters the systemic circulation.

22. Binding to plasma protiens
• Drugs usually tend to bind to plasma protein
(usually albumin), drug binding is reversible,
drugs have different affinities binding to these
proteins.
• Only unbound form of the drug (free form)
move out of the bloodstream to the site of action.
•
• Unbinding to plasma proteins. is necessary to
reveal the pharmacological action.

23. Pharmacodynamics:
• The action of the drug to our body.
• Binding of drug to the receptor is the first step in
the sequence of action,
• Agonist drug: bind to and activate receptor
directly or indirectly,
• Antagonist: binds to a receptor, preventing
binding by other molecules,
e.g. atropine blocking of acetylcholine receptor

26. • Agonist: Drug that bind to a receptor and
produces a biologic response that mimic the
response to the endogenous ligand (the
largest response that the tissue is capable
giving). In general, an agonist has a strong
affinity for its receptor and good/high efficacy.
• Antagonist: Antagonists are drugs that
decrease or oppose the actions of another drug
or endogenous ligand.
Pharmacodynamic

27. • Duration of drug action:
- as long as the receptor is occupied
- action may persist after drug dissociation
because some coupling molecule is still present
in activated form
Pharmacodynamic

28. Routes of administration:
• Oral
• Topical
• Rectal
• Parenteral
• Vaginal
• Inhaled
• Ophthalmic
• Otic

29. Routes of administration:
• (1) Oral Route: - In this route the drug is
placed in the mouth and Swallowed.
• Advantages of Oral Route :
• Convenient - Can be self- administered, pain
free, easy to take
• Absorption - Takes place along the whole length
of the gastro intestinal tract
• Cheap - Compared to most other parenteral rout

30. Routes of administration:
• Disadvantages of Oral Route:
• Sometimes inefficient - only part of the drug
may be absorbed
• Irritation to gastric mucosa - nausea and
vomiting
• Effect too slow for emergencies
• Unpleasant taste of some drugs
• Unable to use in unconscious patient

31. Routes of administration:
• Sublingual: In this route of administration
the drug is placed under the tongue, And it is
taken without the use of water.
• When it is placed under the tongue it
disintegrates there and then absorption occurs
in mouth.
• The tablets are small in size which is to be used
through the sublingual route. Example of
Sublingual tablet is Nitroglycerine tablets.

32. Routes of administration:
• Buccal Route:
• In this route of administration the drug is kept
in the buccal cavity where it disintegrates and
absorption occurs in the mouth.

33. Routes of administration:
• Parenteral Routes:
• In this route of administration the drug does not
pass through the gastrointestinal tract. It
directly reaches to the blood.
• in this class the drugs are administered with the
use of injections e.g. Intravascular,
Intramuscular, Subcutaneous.

34. Routes of administration:
• 1. Intravascular:
• In this route of administration the drug is
directly taken into the blood with the help of
injection.
• Advantages:
• 1. Precise, accurate and almost immediate
onset of action
• 3. Can be given to unconscious patients.
• 4. Quick action

35. Routes of administration:
• 2. Intramuscular:
• In this route of administration the drug is given into
the muscles with the help of injection. Drug once
reaches to the muscles, absorbs into the blood.
• 3. Subcutaneous:
• In this route of administration the drug is given into
the subcutaneous layer with the help of injection.
Drug once reaches to the subcutaneous layer crosses
the membrane and absorbs into the blood.

36. Routes of administration:
• Local/Topical Route of Drug Administration
In this route the drug is applied on the skin and
mucous membrane for the local action.
• Mucosal membranes (eye drops, antiseptic,
sunscreen, callous removal, nasal, etc.)
• Dermal - Rubbing in of oil or ointment (local
action).
• Transdermal - Absorption of drug through
skin (systemic action)

37. Routes of administration:
• Inhalation :
• Volatile liquids and gases are given by inhalation for
systemic effects, e.g. general anaesthetics.
Advantages:
• 1-Quick onset of action
• 2-Dose required is very less, so systemic toxicity is
minimized
• 3-Amount of drug administered can be regulated.
Disadvantages :
Local irritation may cause increased respiratory
secretions and bronchospasm.

38. Routes of administration:
• Rectal Route:
• Drugs can be given in the form of solid or liquid.
• 1. Suppository: It can be used for local (topical) effect
as well as systemic.
• 2-Enema: can be used for local effect as well as systemic
effect. The drug is absorbed through rectal mucous
membrane and produces systemic effect, e.g. diazepam
for status epilepticus in children.

39. Routes of administration:
• Ophthalmic : eye drops or eye ointments.
• Otic : ear drops or sprays.
• Vaginal : pesseries or creams.

41. Factors that modify client’s response
to drugs: