Class 1: Principles of Pharmacology I

D/H  x   V   =   X

Basic dosage calculation formula

D: dose desired

H: dose on hand (how it comes, can be pill etc.)

V: vehicle (form drug is in)

X: amount to administer

What do variables mean in the Basic formula? [4]

1mg= 1000mcg

Conversion from mcg to mg

•Pharmacology

•Study of drugs and interactions with living systems

Pharmacotherapeutics

Use of drugs to diagnose, prevent or treat disease, or prevent pregnancy

Chemical name

Chemical description of the drug

Generic name

Name assigned by the united states adopted name council; same names in canada (ex: ibuprofen)

Trade name

Property or brand name of a drug. Sometimes different in US and Canada

Therapeutic family and pharmacologic family

Two ways to classify drugs

Therapeutic family

Drug classification for the condition they treat

Pharmacologic family (there can be multiple pharmalogic families in a therapeutic family)

Drug classification by their mechanism of action

1. They modify existing functions in the body. They do not confer new functions.

2. They exert their actions on multiple systems.

3. They interact with molecules which are normal points of control of physiological processes.

Three basic properties of drugs [3]

They are not magic. They modify existing functions in the body

How do drugs work?

1. effectiveness: do what it is meant to do

2. Safety: risk benefit ratio

3. selectivity: targets the molecules it needs to target

Top three properties of an ideal drug

•Effectiveness 

•Safety 

•Selectivity 

•Reversible action   

•Predictability

•Ease of administration

•Freedom from drug interactions

•Low cost

•Chemical stability

•Possession of a simple generic name

All properties of an ideal drug [10]

Single action drug

Drug that does it one thing and does it well so that no other drugs are necessary. The more drugs, the more risk of side effects.

Start low, go sow. If a patient is just starting a medication, always start with low dose and increase

Cardinal rule of med administration

• have they had it before?

• Have they had any side effects?

• pain level? [etc]

Questions to ask during pre-administration assessment [3]

1. Identify high-risk patients

2. Justify or question the appropriateness of prescription

Pre-administration assessment: what two main things to do?

1. patient/person

2. medications

3. dose

4. time

5. route

6. assessment

7. evaluation

8. education

9. refuse

10. documentation

Ten rights of medication

1. When you take the medication out of where it is housed: make sure it is the right med, dose, time, and the expiry date

2. After you gather supples, prior to drawing the medication: compare medication in hand to administration record

3. Once medication is drawn up, prior to putting container back/ disposing it

when do you do the three checks of medications?

1. Visual acuity

2. Manual dexterity

3. Intellectual Ability

4. Memory

5. Finances

6. Cultural attitudes

Capacity for self-care factors: [6]

• IM

• IV

• Oral

• Sublingual

• transdermal

• inhalation

• rectal

• Vaginal

Routes of medical administration [8]

Pharmacokinetics

Drug movement throughout the body.

Pharmacodynamics

Interaction between drugs and their receptors

• administration

  • medication calculation and dosing

  • patient adherence

• Pharmacokinetics

• Pharmacodynamics

• Individual variations (enzymes affecting metabolism)

Factors influencing drug responses [6]

• Absoprtion

• Distribution

• Metabolism

• Excretion

Pharmackinetic factors that determine the intensity of the drug response [4]

• drug-receptor interaction

• patient functional state

• placebo effects

Pharmacodynamic factors that determine the intensity of drug response [3]

• medication errors

• patient compliance/adherence

Adminstration factors that determine the intensity of a drug response [2]

1. physiologic variables

2. pathological variables

3. genetic variables

4. drug interactions

Four variables that are sources of individual variation

1. drug absorption

2. Drug distribution

3. Drug metabolism

4. Drug excretion

Four major pharmacokinetic processes

Through cell membranes

How do most drugs get into the body

1. through cell membranes (most common)

2. Passage through channels/ports

3. Passage with the aid of transport systems

How drugs cross biological membranes: [3]

1. antidepressents

2. pain medications

3. anti-anxiety medications

4. some chemotherapies

Drugs that need to get to the brain:

no

Can polar molecules cross the cell membrane

They always favour pH where they become ionized

how do drugs follow pH gradients?

the higher the solubilty, the easier it is for it to pass

Lipid solubility and ease of pass through cell membranes

ions and polar molecules

two things that cannot pass cell membrane

The higher the solubility the faster the onset

Drug onset as it relates to lipid solubility

1. Rate of dissolution

2. Surface area

3. Blood flow to admin site

4. Lipid solubility

5. pH partitioning

Factors that affect drug absoprtion

Stomach content affects pH, which is why some drugs are taken on an empty/full stomach. pH affects whether they stay or leave the blood stream.

Stomach pH and drug absorption

1. Cardiac output/regional blood supply

2. Blood-brain barrier

3. placental drug transfer

4. protein binding

Factors influencing drug distribution

Drug distribution

Movement of drugs in the bloodstream

They are destroyed by gastric enzymes

Why can some drugs ot be taken orally?