n153 week 1

drug action

Molecular change upon binding.

drug effect

change in physiology (broad effect)

specific drug effect

effect caused by what the drug chemically does in the body. (universal)

non-specific drug effect

effects based on the individual’s characteristics rather than the chemical activity itself. (environmental, mindset, etc.)

Placebo

Inert compound w/ no effect. mindset changes effect. placebo must be addressed when developing medications.

nocebo

not inert, a negative response to the medication based on negative expectations.

bioavailability

amount of drug that is available to bind, percentage in blood.

Pharmacokinetic factors

• route of administration

• absorption/distribution

• binding

• inactivation

• excretion

first pass metabolism

breakdown of the drug by the intestines & liver causes a reduced bioavailability.

oral administration

• safer, since you’d vomit if you took too much

• food intake may alter absorption, liver degrade 90%

• lowest bioavailability due to first-pass metabolism

IV administration

• fastest, but shortest effect

• 100% bioavailability

• instant onset

• requires control and accuracy, overdose risk.

IM administration

• slower, more even onset

• if you constrict blood vessels, you decrease absorption, which extends the therapeutic effect of the drug.

• oil lasts longest

subcutaneous administration

• steady and slow absorption

• dilate blood vessel by massaging muscles to increase absorption.

• least availability behind po.

inhalation admin

• oral=lungs

• nasal=brain

• can cause irritation

intranasal

• avoids first pass

• faster absorption

passive diffusion

movement across cell membrane from high to low concentration without using ATP. (lipid molecules). moves down concentration gradient.

concentration gradient

gradual change in concentration of a solute between two regions.

phospholipid bilayer

selective cell barrier

partition coefficient

predicts how well a drug/molecule can pass through the membrane. ratio of dissolving in oil/dissolving in water.

pka vs ph

pka is a fixed, intrinsic chemical property. shows tendency to give up/accept proton. pH is a description of the outside environment.

what affects absorption?

membrane transport, ionization, rate of stomach emptying (more stomach emptying increases absorption), size of pt, gender.

Blood Brain Barrier

BBB

• selectively permeable

• separate capillaries and csf

• endothelial cells form tight junctions on capillaries, closing gaps.

• astrocytes help with leaking

glial cells

non-neuronal cells in the nervous system

astrocytes

glial cells that wrap around capillaries to prevent leaking

area postrema

“vomiting center”, region where the BBB protection is reduced, allowing it to detect substances in the blood.

drug depots

silent receptors, a non-regulatory site that has no effect. reduces drug concentration. non-selective, competitive, prolongs drug in body. reduces drug at