Pharmacology: Drug Excretion, Kinetics, and Blood-Brain Barrier

Teratogens

agents that produce abnormalities

Most common route of drug excretion?

Kidneys (urine

Zero order kinetics

constant rate regardless of concentration (alcohol)

Steady state concentration

level of drug achieved in the blood with repeated regular usage

Therapeutic drug monitoring

to see if the drug threshold is the correct amount, certain drug thresholds change due to age, weight and metabolism, certain drugs have therapeutic windows (meaning there are hours where they are more or less effective)

Reasons for Therapeutic drug monitoring

Test someone's blood after usage to determine if there are kidney or liver effects or to get an idea of drug adjustments

To see what threshold time period there is to determine the best response

Example: antidepressants take weeks to kick in, monitor to determine how many weeks it takes for it to work

Two concerns with people using inhalants?

Deprivation of oxygen and certain inhalants can be teratogens (effecting development)

Difference in inhalants compared to other drugs?

Younger people since they have easier access to obtain them

If a fetus is exposed to a drug, what is the most dangerous trimester to be exposed?

First trimester because major organs are forming during this time

Where are most drugs metabolized in the body

Liver

When a drug has an active metabolite, what is the general effect of that?

Most likely to be a longer lasting drug

What is a depo injection?

Someone who cannot swallow a pill, for example a patient who is psychotic or unable to swallow medically takes this, shot in thigh is easier

Common outcome of enzyme induction?

tolerance , or metabolic tolerance

Two reasons why most drugs that are administered through the GI tract are absorbed through your intestines

Small intestines are large, and the PH of the small intestine is neutral so drugs are be ionized and cannot cross

Time period when enzymes break down drugs more easily and faster

Enzyme induction

First order kinetics

drug clearance most often occurs to redistribution, slower prolonged drop due to metabolism

Placental barrier

a membrane between the maternal and fetal blood in the placenta, it allows transfers of gas and nutrients in without disrupting the fetus from any harmful substances

Pericytes

Regulate BBB blood flow and stability

Curare

potent, plant derived paralytic poison that paralyzes skeletal muscles by blocking the acetylcholine, preventing nerve endings from reaching muscles

Eyes and ears contain mucous membranes because

Usually for local administration like red eyes or pink eyes

History of LSD being absorbed through eyes

Rectal administration

becomes an option when someone is

Unable to swallow

Unconscious

Vomiting

Infants in need of meds

Persistent seizures

First pass metabolism

oral drug is administered that are metabolized by liver enzymes before they even reach their target, reducts bioavailability

Example of first pass metabolism drug

Buspirone

Disadvantages of first pass drug

not last as long

- possibility of effects hitting harder

Advantages of first pass drug

Fewer side effects

Less chance of overdose

Ionization

Dissolved water most drugs become partially ionized, or charged

This depends on: PH levels

Endothelial cells

form tight conjunctions that restrict passage ways

Astrocyte feet

help maintain BBB integrity

Basement membrane

supports the structure of the BBB

What drug disrupts the BBB?

Cocaine because of cell death