Psychopharm for COMPS Flashcards
the amount of drug reaching systemic circulation, the amount of the drug administered that reaches its target.
bioavailability
Decreases bioavailability because a significant amount of drug is metabolized before reaching the blood stream. Hepatic _____: the loss of the drug as it passes through the liver the first time. Sublingual administration avoids this.
First Pass Effects
two phases are completed for ______ of the drug from the blood throughout the body. Organs with rich supplies of blood flow (kidney, liver, heart, brain) are preferred as the first phase. The second phase includes muscle and fat tissues, which have less circulation. When the flow of drug between these different compartments is stable, equilibrium has been reached. The serum level of a drug is the concentration of the drug in the organs and tissues.
distribution
Also known as biotransformation, this is the body’s reaction to foreign compounds – breaking them down for elimination.
Metabolize
The process by which drugs are eliminated from the body, occurring mostly in the kidneys through the urine, but also through the GI tract, respiratory system, sweat, saliva, and breast milk.
Excretion
The amount of time required for the serum concentration to be reduced 50 percent
Half-Life
Occurs when the amount of the drug going into the system (drug absorption) is equal to the amount of the drug going out (drug elimination).
steady state
Norepinephrine is produced:
Tyrosine– DOPA–DA–NE.
Norepinephrine is destroyed:
NE action can be terminated by several mechanisms: Transported out of the cleft and back into the presynaptic neuron via a transporter, specific to NE (norepinephrine transporter – NET)
VMAT then picks up NE for repackaging in vesicles
Can be broken down extracellularly (outside the neuron) by an enzyme (catechol-O-methyl transferase – COMT enzyme)
MAO-A/MAO-B enzymes – are present in the presynaptic neuron; come from the mitochondria to destroy or break down NE
Dopamine is produced
Tyrosine–DOPA–DA
Tryptophan transported into the serotonin neuron by the transporterEnzyme TRY-OH converts it to 5HTPconverted to 5HT by enzyme AAAD-carboxylase. Then VMAT2 takes it up into the synapse to be packaged into the vesicles, where it stays until a neuronal impulse/AP leads to its release.
Serotonin (SA) is produced
o Enzymes, MAO-A/MAO-B, both exist outside the presynaptic neuron and can break SA down o MAO-B is also found intracellularly for breaking down SA o SERT (serotonin transporter) pump moves it into the cell o VMAT2 picks up SA and moves it into vesicles for storage and repackaging
Serotonin is destroyed
o As effective as today’s more common SSRIs but more toxic
♣ They block the presynaptic reuptake transporter for norepinephrine and/or serotonin (therapeutic effect)
♣ They block postsynaptic receptors for histamine, acetylcholine, and norepinephrine (side effects)
o Relatively long half lives
o Metabolized in liver
o Readily cross placental barrier
o All attach to and inhibit the presynaptic transporter proteins for both norepinephrine and serotonin – therapeutic efficacy
Considered “dirty” – react with a number of receptors besides the one responsible for the therapeutic effect
Tricyclics
o Potentiates norepinephrine – blocks the reuptake
o Mild anticholinergic effects
o Sedating
Heterocyclics – Second Generation – Atypical Antidepressants
♣ Blocks the activity of the enzyme to limit the breakdown of NT, allowing for more NT to be packaged and released when an action potential signals
Monoamine Oxidase Inhibitors (MAOIs)
