Basics of Pharmacology

What is pharmaceutics?

-the science of preparing drugs for administration

-”Dosage Forms”

What is pharmacokinetics?

what the body does to the drug

What is pharmacodynamics?

what the drug does to the body

What are properties of drugs?

-Modify existing functions

• replace-iron in anemia

• interrupt

• potentiate

-Drugs exert multiple effects

• Minoxidil: lower blood pressure and prevent hair loss

-Interact with something to exert an effect

What are the levels of drug activity? What do they do?

-Body Systems

• what is it measuring? (reduces pulse rate)

-Component Tissues

• where is it working? (negative chronotope)

-Cellular Level

• how is it affecting cells? (prevnts elevation of cAMP)

-Molecular Level

• competitive antagonism of norepinephrine to cardiac beta 1 receptors

What is an agonist?

-production of a molecular/cellular response to an interaction between a molecule and a receptor that activates the receptor

-can be a drug or endogenous ligand

What is a full agonist?

-increasing concentrations of the agonist will produce an increase in biologic effect up to an intrinsic activity of 1

What is a partial agonist?

-increasing concentrations of the agonist will produce an increase in biologic effect up to an intrinsic activity of <1

What is an antagonist?

-binding of a drug to a receptor that does NOT activate the receptor and prevents a response to an agonist

What is a noncompetitive antagonist?

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

-IRREVERSIBLE

What is a competitive antagonist?

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

What levels do agonist and antagonist act at?

cellular and molecular level

Do you need to bind all receptors to reach max activity in full agonism?

no and adding more agonists after max activity is reached will not change anything

What is pharmacologic antagonism?

two drugs compete at the same receptor

What is effect antagonism?

two drugs act at different receptors but counter each other

What does it mean to get drug into the body?

it has to pass through the biological membrane

What are the forms of enteral administration?

-mouth

-stomach

-small intestine

-rectal

what are properties of the mouth

-thin lining, rich blood supply

what are properties of the stomach

-medium surface area, rich blood supply, acidic pH

-drugs dont stay here

-little to no absorption

what are properties of the small intestine

-huge surface area, rich blood supply, basic pH

-lots of absorption

what are properties of the rectal

-small surface area, rich blood supply, basic pH

What are the advantages of parenteral administration?

-can be used for drugs that are poorly absorbed

• vancomycin < 10 percent is absorbed

-can provide an immediate onset of action (IV)

• opioid analgesics

-can provide a longer lasting effect (IM/SQ)

• antipsychotics

-can concentrate drug at specific location (IA)

• corticosteroids in joint

-can provide a more predictable response

• antibiotics in a septic patient

-can provide titratable dosage

• heparin infusions

What are the disadvantages of parenteral administration?

-pain

-irreversible

-extravasation -escape of blood from the blood vessel into the tissue

-phlebitis -inflammation of vein

-not useful for self-admin

-contamination/infection

Why are veins used more than arteries in parenteral administrations

veins have lower pressure and are less susceptible to severe blood loss

What are the types of parenteral administration

-intravenous

-intra-arterial

-intramuscular: usually a vaccine

-epidural: in epidural space NOT CSF

-intrathecal: directly into CSF

-subcutaneous

-intra-articular: into a joints

Skin topical administration

-ointments, creams, patches

-local and systemic

Eyes topical administration

-drops and ointment

-LOCAL ONLY

Ears topical administration

-external

-LOCAL ONLY

Intranasal topical administration

-spray and drops

-local and systemic

Inhalation topical administration

-local and systemic

Vaginal topical administration

-local and systemic

What is the pharmaceutical phase: disintegration

increases the surface area by breaking drug up into a bunch of little pieces

What is the pharmaceutical phase: dissolution

dissolving the drug down to its molecular particle to pass through the biological membrane

What are the oral dosage forms from fastest to dissolve to slowest

-dissolved liquid (elixir, syrup)

• already been dissolved down to its molecular form

- suspensions

• MUST SHAKE

• drug has been disintegrated not dissolved

-powders

• not common

-capsule

• powder inside a gelatin capsule that is dissolved in the stomach

-tablets

• has to disintegrate and dissolve

-coated tablets

• has a spray coating to delay absorption, mask a bad taste, make the pill easier to swallow or just hold tablet together

-enteric coating

• coating that protects from acidic environments

-sustained release

• made to last longer

What are the types of absorption of a drug

passive or facilitated

the rate of a drug absorption can determine

-onset of action

-duration of action

-intensity of response

What are variables affecting absorption?

-nature of absorbing surface

-surface area

-blood flow to site

-pH at the site

What are the types of drug elimination

biotransformation or excretion

What is biotransformation?

changing the active drug into something that is no longer active

-hepatic metabolism

What are the tissue enzymes in biotransformation

GI tract, lungs, kidneys

What is excretion?

moving the active drug out of the body

-kidneys

-lungs

-sweat glands

-mammary glands

-GI tract

What are variables that affect dose/response

-body weight

-age

-gender

-genetics

-tolerance

-psychological factors

-comorbid medical conditions

How can body weight affect dose/response to drug

-larger doses are often given to patients with greater weight or BMI

• dependent on where the drug distributes to: muscle, adipose, body water

How does age affect dose/response to drug

-altered capacity to metabolize and/or excrete drugs (usually decreased)

-most common in very young and very old

How does gender affect dose/response to drug

differences in body composition and hormonal activity

How do genetics affect dose/response to drug

-enzymatic differences can lead to alterations in magnitude of effect

How does tolerance affect dose/response to drug

-larger doses must be given to maintain the same effect

-commonly seen with opioids

How do psychological beliefs affect dose/response to drug

placebo effect

How do comorbid medical conditions affect dose/response to drug

-can affect all phases of pharmacokinetic and pharmacodynamic response