Pharmacology
STUDENT ACTIVITY SHEET BS NURSING / SECOND YEAR
Session 1
LESSON TITLE: INTRODUCTION TO PHARMACOLOGY Materials:
LEARNING OUTCOMES: Notebook, pens ,paper and index card
At the end of the lesson, the nursing student can:
References:
1. Differentiate the three phases of drug action; Kee, Joyce LeFever, Hayes, Evelyn R. &
2. Describe the four processes of pharmacokinetics; McCuistion E. Pharmacoloy A Nursing
3. Explain the meaning of pharmacodynamics Process Approach 6th edition.. Singapore:
4. Define the terms half- life, therapeutic index, Elsevier Saunders Company.
therapeutic drug range, side effects, adverse reaction
and drug toxicity.
SUBJECT ORIENTATION & GETTING TO KNOW EACH OTHER ACTIVITY (20 minutes)
You will now take note everything about the subject orientation
1. Calendar of activities
2. Classroom rules and regulations
3. Computation of grades
4. Grading of modules
5. Election of officers
6. Requirements – Drug study per period/ term
MAIN LESSON (45 minutes)
THREE PHASES OF DRUG ACTION
1st 2nd 3rd
Pharmaceutic Pharmacokinetics Pharmacodynamics
Solid form Absorption Drug action : onset, peak &
Liquid form Distribution duration
Metabolism / Receptors
Biotransformation Enzymes
Excretion Hormones
I. Pharmaceutic Phase
o Disintegration – is the breakdown of tablet into smaller particles
o Dissolution - dissolving of the smaller particles in the GI fluid before absorption
o 1st phase of drug action
o Rate limiting – time it takes for the drug to disintegrate and dissolve to become available for the body to absorb it.
,II. Pharmacokinetic Phase
, o Is the process of drug movement to achieve drug action
o 2nd phase of drug action
o What the body does to the drug- refers to the study of how the body processes drugs
o It includes the 4 basic components of :
1. Absorption
2. Distribution
3. Metabolism (Biotransformation)
4. Excretion
1. Absorption – the movement of drug particles from the G.I. tract to body fluids by :
a. Passive absorption
b. Active absorption
c. Pinocytosis
a. Passive absorption
o Movement of a drug from the site of administration into the bloodstream.
o Absorption determines how long it takes for a drug to take effect.
o Usually the more rapid the absorption, faster the drug works
o Drugs can be absorbed through plasma primarily by: Diffusion (movement from higher concentration to lower
concentration)
o Does not require energy to move across the membrane.
b. Active absorption
o Requires a carrier such as an enzyme or protein
o Energy is required for active absorption
c. Pinocytosis
o Process by which cells carry drug across their membrane by engulfing the drug paticles
Factors Affecting Absorption
o Surface area
o Contact time with surface
o Circulation
o Solubility (water soluble vs lipid soluble)
o Ionization (weak versus strong acid/base)
o Drug form & drug concentration
o Bioavailability ( after first pass thru liver)
o Route of administration (enteral & parenteral)
o Additives: alter the location of disintegration of drugs as well as increase or decrease the rate of absorption
o Enteric coating allows a drug to dissolve only in an alkaline (pH greater than 7.0) environment such as the
small intestine.
o Sustained release drugs:allow drugs to be released slowly over time, rather than quickly, like conventional
tablets.
o Size of drug particles: smaller the particle, faster the onset.
Drug Absorption varies by form
Liquids, elixirs, syrups Fastest
Suspension solutions
Powders
Capsules
Tablets
Coated tablets
Enteric-coated tablets Slowest
2. Distribution: the transport of drugs from the blood to the site of action. A drug must be distributed to its site of action
to have an effect
, o Drugs are also distributed to tissues where it has no effect. Competition for drug binding sites affects the amount
of drug available for action in the body.
o Volume of Distribution (Vd) - The degree of distribution of a drug into various body compartments and tissue
Factors Affecting Distribution
1. Perfusion Rate
2. Permeability of Membranes
3. Protein binding
4. Tissue Localization
5. Blood Brain Barrier
6. Placenta
3. Metabolism (breakdown of the drug)
o Biotransformation: process by which the body changes the chemical structure of a drug to another form called a
metabolite.
o Metabolite: a more water soluble compound that can be easily excreted. The major organ for this process is the
liver
o First Pass Phenomenon - Drugs are first absorbed through the small intestine then arrive at the liver via the
portal circulation
o There they undergo considerable biotransformation before entering the systemic circulation.
o There will be less active drug available for action in the body cells after this first Pass through the Liver
Variations in Metabolism
o Pharmacogenetics - hereditary influences on drug responses, refers to variations in which individuals
metabolize drugs.
o Circadian Rhythms - the rate of drug absorption, hepatic clearance, half-life and duration of action, have all
been shown to differ depending upon the time of day a drug is administered.
o Effects of Gender and Age
Elimination of the drug from the body is directly influenced by age. Newborns and elderly experience the
effects of drugs for longer and the drug takes a lot longer to be eliminated from the body.
• Newborns : When babies are born to term, their renal function is very quick to establish similar levels to adults wi thin
one week after birth. If the baby is born prematurely it can take 8 weeks or more to reach the level of enzymes
necessary. If drugs are given before the renal function is at this level, the drug elimination from the body takes a lot
longer and so do the effects of the drugs.
• Elderly : Renal filtration rate begins to decline at 20 years of age and by 50 years of age it has declined by 50%. This
again will affect the elimination of drugs from the body.
4. Excretion: process where drugs are removed from the body. Kidneys are the major organs of excretion.
o Lungs excrete gaseous drugs.
o Biliary excretion (bile & feces) is important for a few drugs. These drugs may be reabsorbed when passing
through the intestines from the liver ( enterohepatic re-circulation ).
o Intestines, sweat, saliva and breast milk constitute minor routes of drug excretion
o Clearance of drugs - elimination of drugs from circulation by all routes. It affects the time a drug remains in the
body and the dosage required.
Renal Clearance
Hepatic clearance
PLASMA HALF-LIFE
o The elimination half-life of a drug is a pharmacokinetic parameter that is defined as the time it takes for the
concentration of the drug in the plasma or the total amount in the body to be reduced by 50%. In other words, after
one half-life, the concentration of the drug in the body will be half of the starting dose.
o Drugs with short half-lives are quickly eliminated from the body. ( Ex: analgesics : given several X per day )
o Drugs with longer half-lives stay in the body longer
(Ex: Digoxin given once a day )
III. PHARMACODYNAMIC PHASE
o What a drug does to the body- refers to the study of the mechanism of drug action on living tissue.
STUDENT ACTIVITY SHEET BS NURSING / SECOND YEAR
Session 1
LESSON TITLE: INTRODUCTION TO PHARMACOLOGY Materials:
LEARNING OUTCOMES: Notebook, pens ,paper and index card
At the end of the lesson, the nursing student can:
References:
1. Differentiate the three phases of drug action; Kee, Joyce LeFever, Hayes, Evelyn R. &
2. Describe the four processes of pharmacokinetics; McCuistion E. Pharmacoloy A Nursing
3. Explain the meaning of pharmacodynamics Process Approach 6th edition.. Singapore:
4. Define the terms half- life, therapeutic index, Elsevier Saunders Company.
therapeutic drug range, side effects, adverse reaction
and drug toxicity.
SUBJECT ORIENTATION & GETTING TO KNOW EACH OTHER ACTIVITY (20 minutes)
You will now take note everything about the subject orientation
1. Calendar of activities
2. Classroom rules and regulations
3. Computation of grades
4. Grading of modules
5. Election of officers
6. Requirements – Drug study per period/ term
MAIN LESSON (45 minutes)
THREE PHASES OF DRUG ACTION
1st 2nd 3rd
Pharmaceutic Pharmacokinetics Pharmacodynamics
Solid form Absorption Drug action : onset, peak &
Liquid form Distribution duration
Metabolism / Receptors
Biotransformation Enzymes
Excretion Hormones
I. Pharmaceutic Phase
o Disintegration – is the breakdown of tablet into smaller particles
o Dissolution - dissolving of the smaller particles in the GI fluid before absorption
o 1st phase of drug action
o Rate limiting – time it takes for the drug to disintegrate and dissolve to become available for the body to absorb it.
,II. Pharmacokinetic Phase
, o Is the process of drug movement to achieve drug action
o 2nd phase of drug action
o What the body does to the drug- refers to the study of how the body processes drugs
o It includes the 4 basic components of :
1. Absorption
2. Distribution
3. Metabolism (Biotransformation)
4. Excretion
1. Absorption – the movement of drug particles from the G.I. tract to body fluids by :
a. Passive absorption
b. Active absorption
c. Pinocytosis
a. Passive absorption
o Movement of a drug from the site of administration into the bloodstream.
o Absorption determines how long it takes for a drug to take effect.
o Usually the more rapid the absorption, faster the drug works
o Drugs can be absorbed through plasma primarily by: Diffusion (movement from higher concentration to lower
concentration)
o Does not require energy to move across the membrane.
b. Active absorption
o Requires a carrier such as an enzyme or protein
o Energy is required for active absorption
c. Pinocytosis
o Process by which cells carry drug across their membrane by engulfing the drug paticles
Factors Affecting Absorption
o Surface area
o Contact time with surface
o Circulation
o Solubility (water soluble vs lipid soluble)
o Ionization (weak versus strong acid/base)
o Drug form & drug concentration
o Bioavailability ( after first pass thru liver)
o Route of administration (enteral & parenteral)
o Additives: alter the location of disintegration of drugs as well as increase or decrease the rate of absorption
o Enteric coating allows a drug to dissolve only in an alkaline (pH greater than 7.0) environment such as the
small intestine.
o Sustained release drugs:allow drugs to be released slowly over time, rather than quickly, like conventional
tablets.
o Size of drug particles: smaller the particle, faster the onset.
Drug Absorption varies by form
Liquids, elixirs, syrups Fastest
Suspension solutions
Powders
Capsules
Tablets
Coated tablets
Enteric-coated tablets Slowest
2. Distribution: the transport of drugs from the blood to the site of action. A drug must be distributed to its site of action
to have an effect
, o Drugs are also distributed to tissues where it has no effect. Competition for drug binding sites affects the amount
of drug available for action in the body.
o Volume of Distribution (Vd) - The degree of distribution of a drug into various body compartments and tissue
Factors Affecting Distribution
1. Perfusion Rate
2. Permeability of Membranes
3. Protein binding
4. Tissue Localization
5. Blood Brain Barrier
6. Placenta
3. Metabolism (breakdown of the drug)
o Biotransformation: process by which the body changes the chemical structure of a drug to another form called a
metabolite.
o Metabolite: a more water soluble compound that can be easily excreted. The major organ for this process is the
liver
o First Pass Phenomenon - Drugs are first absorbed through the small intestine then arrive at the liver via the
portal circulation
o There they undergo considerable biotransformation before entering the systemic circulation.
o There will be less active drug available for action in the body cells after this first Pass through the Liver
Variations in Metabolism
o Pharmacogenetics - hereditary influences on drug responses, refers to variations in which individuals
metabolize drugs.
o Circadian Rhythms - the rate of drug absorption, hepatic clearance, half-life and duration of action, have all
been shown to differ depending upon the time of day a drug is administered.
o Effects of Gender and Age
Elimination of the drug from the body is directly influenced by age. Newborns and elderly experience the
effects of drugs for longer and the drug takes a lot longer to be eliminated from the body.
• Newborns : When babies are born to term, their renal function is very quick to establish similar levels to adults wi thin
one week after birth. If the baby is born prematurely it can take 8 weeks or more to reach the level of enzymes
necessary. If drugs are given before the renal function is at this level, the drug elimination from the body takes a lot
longer and so do the effects of the drugs.
• Elderly : Renal filtration rate begins to decline at 20 years of age and by 50 years of age it has declined by 50%. This
again will affect the elimination of drugs from the body.
4. Excretion: process where drugs are removed from the body. Kidneys are the major organs of excretion.
o Lungs excrete gaseous drugs.
o Biliary excretion (bile & feces) is important for a few drugs. These drugs may be reabsorbed when passing
through the intestines from the liver ( enterohepatic re-circulation ).
o Intestines, sweat, saliva and breast milk constitute minor routes of drug excretion
o Clearance of drugs - elimination of drugs from circulation by all routes. It affects the time a drug remains in the
body and the dosage required.
Renal Clearance
Hepatic clearance
PLASMA HALF-LIFE
o The elimination half-life of a drug is a pharmacokinetic parameter that is defined as the time it takes for the
concentration of the drug in the plasma or the total amount in the body to be reduced by 50%. In other words, after
one half-life, the concentration of the drug in the body will be half of the starting dose.
o Drugs with short half-lives are quickly eliminated from the body. ( Ex: analgesics : given several X per day )
o Drugs with longer half-lives stay in the body longer
(Ex: Digoxin given once a day )
III. PHARMACODYNAMIC PHASE
o What a drug does to the body- refers to the study of the mechanism of drug action on living tissue.
