Weekend 2 lecture 2 Flashcards
Explain Pharmokinetics
What does enternal
parenteral mean?
how is the drug absorbed?”/bioavailability = “how much of the drug is available to be delivered to the target sites.
Drugs enter the body through different routes
Enteral: the drug enters the GI system before it goes into circulation
Parenteral: the drug bypasses the GI system and goes directly into circulation
What is the Bioavability
Decreased distribution as well.
bio-Availability The amount of the drug which is available to the target organ
“first pass effect”
distribution General or restricted depending on the ability of the drug to traverse the cells membranes
What is clearance and what 3 organs are essential for getting rid of the drug.
Describe half life as well.
Clearance - Rate of elimination of the drug by all routes relative to the concentration of the drug in any biologic fluid Mechanisms: Kidney Liver Pulmonary
Half life The time it takes for the the plasma concentration of the drug to be reduced by 50%
The longer the half-life the longer the action of the drug
What are Inotropic drugs?
Drugs used to increase the force of ventricular contraction when myocardial systolic function is impaired.
Thought to work by increasing the intracellular calcium concentration
Digitalis and Cardiac Glycosides what are the desired effects of these medications
Desired effects
Improve contractility of the failing heart
Prolong the refractory period of the AV node in patients with supraventricular arrythmias
How long is the half life for digoxin and how does it get excreted
A series of loading doses must be given to raise the drug’s concentration into therapeutic range
Digoxin is excreted through the kidneys and has a half life of 36-40 hours
Other forms of the drug are excreted through the liver (digitoxin) and have a longer half life
Digoxin Toxicity
Easily toxic because the therapeutic level of the drug is close to the toxic level of the drug.
Signs of digoxin toxicity: nausea/vomiting; anorexia; variety of arrythmias
Sympathomimetic Amines Give some examples of this and what do they do ?
Act by binding to the cardiac Beta 1 receptors, increasing the activity of cAMPincreased release of Calcium from the sarcoplasmic reticulum
Examples: Dopamine, Dobutamine, Norepinephrine, Epinephrine, Isoproterenol
Dopamine Dosages and its effects what does a 1-2 dose do what about a
medimum dose (2-10)
high dose (greater than 10)
Low doses (< 2 micrograms/KG/min) Primarily interacts with receptors which increases blood flow to the kidneys and mesenteric beds Medium doses (2-10) Stimulates the Beta 1 receptorsincreased CO High doses (>10) Also stimulates the alpha receptors causing vasoconstriction and elevating systemic resistance
Phosphodiesterase Inhibitors
Inhibit the actions of phosphodiesterase which reduces the breakdown the cAMP and ultimately enhances the calcium entry into the cell and thereby increases the force of contraction
Intravenous B-type natriuretic peptide (BNP) Just type b personality relaxes people
Natrecor (nesiritide): recombinant human B type natriuretic peptide which is produced by the ventricular myocardium.
It binds to the guanylate cyclase receptor of vascular smooth muscle and endothelial cellsincreased intracellular cGMP with resultant smooth muscle cell relaxation
ACE Inhbitors
Angiotensin converting enzyme is inhibited preventing the conversion of angiotensin Iangiotensin II
Decrease arterial pressure
Facilitate natriuresis (ecrerting sodium out of the kidneys)
Toxcitiy or side effects of Ace Inhibitors just think what it does so what could it cause
Not very common Side effects Hypotension Hyperkalemia Renal insufficiency Cough
Sodium Nitroprusside remember that nitro used in extreme cases good way to remember
A potent dialator of both arteries and veins, used to treat hypertensive emergencies and in ICU settings for IV control of BP
Onset of action is 30sec and its peak effect is achieved in 2 minutes
SNP side effects: blurred vision, tinnitus, disorientation, Nausea—these side effects are associated in metabolic toxic effects of excretion of the drug through the liver
Alpha Adrenergic Antagonists give some examples and what they are used for.
Results in vasodialation
Examples: prazosin, terazosin, doxazosin
Principle indication is hypertension
Direct-Acting Vasodialators
Hydralazine Minoxidil Calcium Channel blockers Diltiazem Verapamil
Calcium Channel Blockers
effects and side effects
Negative inotropic effect
Impeded the influx of calcium across the membrane channels in cardiac and smooth muscle cells
Side effects: hypotension, ankle edema