Basics of Pharmacology

Pharmaceutics

The science of preparing drugs for administration
**how to get drugs into a form that can be taken

Pharmacokinetics

the study of the absorption, distribution, metabolism and elimination of drugs
**what the body does to the drug
**body uses kinetic energy to break down the drug

Pharmacodynamics

the study of the action or effects of drugs on living systems
**what the drug does to the body

general properties of drugs

- Drugs modify existing functions (replace, interrupt, potentiate)
- Drugs exert multiple effects
- Drugs typically interact with something to exert an effect

Level of Drug Activity: body systems

how the body reacts to the medication overall
ex: reduce pulse rate

Level of Drug Activity: component tissues

the organ/tissues that the medication targets
ex: heart (negative chronotrope = slow HR)

Level of Drug Activity: cellular

basic biology level understanding of how the medication works
ex: prevents elevation of cAMP

Level of Drug Activity: molecular

what is happening in/on the cell to produce the desired effect
ex: competitive antagonism of NE to cardiac beta 1 receptors

agonist

a molecule that stimulates a response by binding to a receptor site

partial agonist

a drug with the ability to produce <100% of the maximum response aka intrinsic activity of <1

full agonist

a drug with the ability to produce 100% of the maximum response aka intrinsic activity of 1

antagonism

binding of a drug to a receptor that does NOT activate the receptor and PREVENTS a response

noncompetitive antagonist

aka irreversible antagonist
- block can NOT be overcome by increasing dose of the agonist

competitive antagonist

- block can be overcome by increasing the dose of the agonist

Pharmacologic antagonist (on sight)

any drug that binds to a receptor and blocks the activation of the receptor; deals with ONE type of receptor that multiple drugs are looking to bind

Effect antagonist (petty/passive aggressive)

two different drugs act on two different kinds of receptors and the responses cancel each other out

enteral administration (hint: there's 4)

- mouth
- stomach - acidic pH, bad for absorption
- small intestine - big surface area, best for absorption
- rectal - good for local use

Advantages of Parenteral Administration

Better absorption
IV = immediate onset of action
IM/SQ = last longer
IA = specific location
More predictable response
Titration

Disadvantages of Parenteral Administration

Pain
Irreversible
Extravasation / phlebitis
Typically not self-administered
Contamination / infection

Parenteral administration routes (hint: there's 7)

IV
Intra-arterial
IM
SQ
IA (intra-articular)
epidural
intrathecal

topical administration routes (hint: there's 6. know their distributions too)

eyes - local only
ears - local only
skin
intranasal
inhalation
vaginal

8 oral dosage forms: Dissolved Liquid (elixir, syrup)

1-fastest

8 oral dosage forms: suspensions

2

8 oral dosage forms: powders

3

8 oral dosage forms: capsules

4

8 oral dosage forms: tablets

5

8 oral dosage forms: coated tablets

6

8 oral dosage forms: enteric-coating

7

8 oral dosage forms: sustained-release

8-slowest

rate of absorption can determine

-onset of action
-duration of action
-intensity of response

variables affecting absorption

-nature of absorbing surface
-surface area
-blood flow to site of administration
-pH at the site of absorption

Drug elimination: Biotransformation

drug is still in the body but has been made inactive through hepatic metabolism and/or tissue enzymes

Drug elimination: Excretion

getting drugs out of the body
-kidneys MOST COMMON
-lungs
-sweat glands
-salivary glands
-mammary glands
-GI tract (2nd best)

disintegration

the breakdown of a tablet into smaller particles/chunks
*increases surface area

dissolution

the breakdown of tablet particles into individual molecules
**can cross membranes to be absorbed in the body

variables affecting dose/response

-body weight
-age
-gender
-genetics
-tolerance
-psychological factors/beliefs
-comorbid medical conditions

Post Receptor Effects: Ligand-gated ion channels

Ligand binds to receptor → gate opens → effect

** antagonists will keep it closed

Post Receptor Effects: Sodium Potassium Pump

• Great place for drug therapy

• 2K+ and 3Na+

• Transports ions and stabilizes membrane

Post Receptor Effects: Voltage gated ion channel

Nerve impulses send signal from one point to another

Post Receptor Effects: Enzymes

Speed up or slow down chemical reactions