Pharmacology
Objectives
1. The student will be able to understand how medications are measured
2. The student will know what the FDA is and why they are necessary for safety
3. The student will know what the difference is between the Therapeutic dose and the lethal dose of a
medication and some examples.
4.The student will understand the importance of knowing what drugs can be combined and where to
find that information
5. The student will understand the different types of drug interactions.
It’s all about Metric
The metric system is used for drug dosages,measurement.
Teaspoons, Tablespoons, cups,ounces to pounds are the
familiar measurements
milligrams, grams, kilograms are how things are measured
in the medical world.
Easier than you think. Everything relates by a 10th, 100th or
1000th. Examples
Units of metric measurement
Quantity measured
Unit
mass
milligram
Symbol
mg
Gram
Kilogram
Volume
kg
1000 mg= 1 gram
1 kg= 1000 g
metric ton=1000kg
milliliter
ml
1000 ml= 1 liter
Cubic centimeter
cc
1 ml= 1 cc
Liter
Cubic meter
** 1 tsp= 5 ml
g
Relationship
1 cup=250 ml
l
cm
1000 l= 1 cm
What dose of Motrin?
What dose of Motrin
Overview & Uses
When your child isn't feeling well, bring them relief with Children's MOTRIN®. Its safety profile is supported by one of the largest and most rigorous children's clinical
studies ever conducted. And, it lasts up to 8 hours. Children's MOTRIN® will help you both feel better.
Uses:
Temporarily:
Relieves minor aches and pains due to the common cold, flu, sore throat, headache and toothache
Reduces fever
Naproxen, Aleve, Naprosyn
Naproxen 250 mg or 375 mg or 500 mg twice daily
Naproxen sodium
275 mg (naproxen 250 mg with 25 mg sodium) twice daily
550 mg (naproxen 500 mg with 50 mg sodium) twice daily
What dose of medication?
What volume contains the dose you need?
If you have an ampoule of 500mg in 4ml, and you need 200mg, it can appear to be a daunting
calculation. The first step is to find out what volume contains 1mg (4/500) and then multiply it by
how many mg you want (200).
The easy way to remember this is the famous nursing equation:
‘What you want, over what you’ve got, times what it’s in’
In this instance:
200mg x 4ml / 500mg = 1.6ml
The common error here is to get it upside down, and divide what you’ve got by what you want. This
fortunately gives you a stupid answer, which is obviously wrong, in this case 10ml. You already
know that you need a fraction of an ampoule and not two and a bit ampoules, which highlights the
error.
Oral vs parenteral
Depends on chemical composition and how drug is metabolized.
Definition
Drug metabolism is the process by which the body breaks down and converts medication into active
chemical substances/metabolites
Precautions
Drugs can interact with other drugs, foods, and beverages. Interactions can lessen or magnify the
desired therapeutic effect of a drug, or may cause unwanted or unexpected side effects. There are
thousands of possible drug-to-drug and drug-to-food interactions, and many medications and
supplements are contraindicated (not recommended) under certain conditions or in patients with
specific diseases and disorders. This is why it is imperative that patients always keep their
physician fully informed about all drugs and dietary supplements (including herbal remedies) they
are taking.
Drug Metablolism
Definitions
The Liver-,The primary site of drug metabolism, the organ that plays a major
role in metabolism, digestion,detoxification, and elimination of substances
from the body. A solid organ located on the right in the upper abdomen. It
plays a major role in metabolism, digestion, detoxification, and elimination of
substances from the body.
Enzymes-organic substances (proteins) composed of amino acids that
trigger and regulate chemical reactions in the body. There are over 700
identified human enzymes
Metabolites- Substances produced by metabolism or by a metabolic process.
They are then bound to other substances for excretion through the lungs, or
bodily fluids such as saliva, sweat, breast milk, and urine, or through
reabsorption by the intestines.
Definitions continued
the kidneys-The primary mode of excretion for drug metabolites (where urine
comes from.) We have 2 located both sides of mid back
Cytochrome P-450-The family of liver isoenzymes that are crucial to drug
metabolism
Metabolism-the sum of all the physical and chemical processes occurring in
the body to organize and maintain life
Catabolism- a process of metabolism that breaks down complex substances
into simple ones.
Cirrhosis-Liver disease characterized by the widespread disruption of the
normal liver structure and function.
CNS Depressant- Anything that depresses, or slows, the sympathetic
impulses of the central nervous system (i.e., respiratory rate, heart rate).
Drug metabolism
Drugs can interact with other drugs, foods, and beverages.
Interactions can lessen or magnify the desired therapeutic effect of a drug, or
may cause unwanted or unexpected side effects.
There are thousands of possible drug-to-drug and drug-to-food interactions,
and many medications and supplements are contraindicated (not
recommended) under certain conditions or in patients with specific diseases
and disorders.
This is why it is important that patients always keep their physician fully
informed about all drugs and dietary supplements (including herbal
remedies) they are taking.
Drug Metabolism Physiology
The primary site of drug metabolism is the liver
Enzymes in the liver are responsible for chemically changing drug
components into substances known as metabolites.
Metabolites are then bound to other substances for excretion through the
lungs, or bodily fluids such as saliva, sweat, breast milk, and urine, or
through reabsorption by the intestines. The primary mode of excretion is
through the kidneys.
The family of liver isoenzymes known as cytochrome P-450 are crucial to drug
metabolism. These enzymes (labeled CYP1A2, CYP2C9, CYP2C19,
CYP2D6, and CYP3A4) have a catabolic action on substances, breaking
them down into metabolites. They also act to lower the concentration of
medication in the bloodstream.
Drug Interactions:
Definition
“The pharmacologic or clinical response to the administration of a drug
combination different from that anticipated from the known effects of the two
agents when given alone”
Tatro DS (Ed.) Drug Interaction Facts. J.B. Lippincott Co. St. Louis 1992
Types of Drug Interactions
Pharmacokinetic
- What the body does with the drug
- One drug alters the concentration of another by altering
its absorption, distribution, metabolism, or excretion
- Usually (but not always) mediated by cytochrome P450 (CYP)
- Can depend on absorption (GI motility, pH) Distrubution (transport proteins)
Metabolism, (CYP450). Elimination(renal Kidney function)
Pharmacodynamic drug interactions
Synergistic combinations
Phamacologic (drug) effect is greater than the summation of the 2 drugs
sometimes beneficial and sometimes harmful
Beneficial: aminoglycoside +penicillin cell wall breakdown by PCN
Harmful: barbituates and alcohol alcohol enhances the effects of the barbituate
Antagonistic combinations
Pharmacologic effect is less than the summation fo the 2 drugs
Beneficial: Naloxone(Narcan) in opiate overdose
Harmful zidovudine + stavudine used in treating HIV one makes the other
ineffective
Additivity effect
equals the summation of the 2 drugs
Beneficial: Asprin + acetaminophen both work together to relieve pain better
Harmful: neutropenia with zidovudine + ganciclovir (HIV drugs) blood toxicity
Drug interactions
*Drug interactions can occur when one drug inhibits or induces a P-450 that
acts on another drug. An example is nicotine, a drug contained in tobacco,
and known to induce P-450s.
*Individuals with liver disease (ie: cirrhosis) may have insufficient levels of P450 enzymes. As a result, the concentration of drugs metabolized by these
enzymes remains high and can build up to toxic levels in the bloodstream
*certain medications and foods, such as grapefruit juice, can inactivate or
lessen the metabolic activity of P-450s.
*The metabolic rate can vary significantly from person to person, and drug
dosages that work quickly and effectively in one individual may not work well
for another. Factors such as genetics, environment, nutrition, and age also
influence drug metabolism; infants and elderly patients may have a reduced
capacity to metabolize certain drugs, and may require adjustments in
Common drug interactions
What are some common drug interactions that you can think of?
Are they harmful or beneficial?
Example
What about illegal drugs? How do you know whats really in them if they are
not controlled by the FDA? How do you know the therapeutic dose or the
toxic dose?
Example Opiates. Legal vs illegal Suicide vs accidental overdose
Tylenol (acetaminophen)
Example of a common medication that when taken as prescribed is very safe for
most people but if taken in higher doses or in combination with things is
lethal……
Tylenol (acetaminophen) can purchase by itself or it is contained in some
prescription medications and other over the counter medications. Easy to OD
Why?
The liver breaks down most of the drug into safe components that can be removed
from the body in the urine. However, a small amount of Tylenol is expected to be
metabolized into a harmful by-product called NAPQI (which stands for N-acetyl-pbenzoquinoneimine). When Tylenol is taken in recommended doses, your body
can quickly remove this toxic by-product in the urine. However, when the liver
needs to suddenly metabolize overdose levels of Tylenol, too much of the toxic
NAPQI is made and it starts to harm the main cells of the liver
Medication combinations
Today, more than 600 over the counter and prescription medications contain
tylenol (acetaminophen) Some examples
Alka-Seltzer Plus Liquid Gels
Anacin
Formula 44 cough syrup
Butalbital
Midol
Edocet
Cepacol
nyquil
Hycotab
Contac
Robitussin
Coricidin
Sudafed
Hydrocodone
Dayquil
Midol
Fioricet
Ibuprofen
Advil, Motrin (ibuprofen) alternative pain, fever reducer.
NSAIDS (non steroidal anti inflammatory drug) rarely affect the liver. Unlike
acetaminophen (Tylenol) most NSAIDs are absorbed completely and have
negligible first-pass hepatic (liver) metabolism. In other words, the way
NSAIDS are metabolized makes liver toxicity (hepatotoxicity) very rare.
It’s about the kidneys:
NSAIDs have important adverse effects on the kidney that you should know about. Here is the science
behind the problem. Ibuprofen and other NSAIDs inhibit prostaglandins, and that can cause a
problem because prostaglandins dilate blood vessels leading to the kidneys. Inhibiting prostaglandins
may lead to kidney ischemia (dead tissue from decreased blood flow) and thus acute kidney injury.
Dr. orders in school
PERMISSION TO ADMINISTER MEDICATION AT SCHOOL
Student: _______________________ __________Birthdate: __ _________Grade: _____
PARENT/GUARDIAN SECTION * SECCION DE PADRE/GUARDIAN
I request that the school nurse, or designated staff member, administer the medication prescribed below, in accordance with the healthcare provider
instructions. I give my permission for the following medication information to be shared with school staff on a “need to know” basis.
HEALTH CARE PROVIDER SECTION
Diagnosis for which medication is to be given during school hours:_______________________________
Is this condition Life Threatening? Yes / No
*911 will be called whenever the student’s condition deteriorates
_ ________ __________ ___po_______ Beginning of school after breakfast_
Name of medication (1 per form): Dosage:
Possible
Method of administration: Time o
side effects:____________________________________________Emergency Action:____________________________or
911
When
the parent requests may we give the morning dose of the above
HCP Signature
medication when forgotten at home? Yes / No
Date
FDA Food and Drug Administration
FDA is responsible for protecting the public health by assuring
the safety, efficacy and security of human and veterinary
drugs, biological products, medical devices, our nation's food
supply, cosmetics, and products that emit radiation.
FDA is also responsible for advancing the public health by
helping to speed innovations that make medicines more
effective, safer, and more affordable and by helping the public
get the accurate, science-based information they need to use
medicines and foods to maintain and improve their health.