Save
Busy. Please wait.
Log in with Clever
or
show password
Forgot Password?
Don't have an account?  Sign up 
Sign up using Clever
or
Username is available taken
show password


Make sure to remember your password. If you forget it there is no way for StudyStack to send you a reset link. You would need to create a new account. Your email address is only used to allow you to reset your password. See our Privacy Policy and Terms of Service.

Already a StudyStack user? Log In

Reset Password
Enter the associated with your account, and we'll email you a link to reset your password.
focusNode
Didn't know it?
click below
 
Knew it?
click below
Don't Know
Remaining cards (0)
Know
0:00
edit
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.

  Normal Size     Small Size show me how

Pharm Lect 4

QuestionAnswer
First Pass Effect (metabolism) Drugs that are absorbed by the stomach and GI first pass by bacterial, intestinal wall, and liver enzymes before reaching the systemic circulation. Some drugs are extensively metabolized and their bioavailability decreases.
100mg tablet has 30% bioavailability due to first pass effect, how much of the tablet makes it into systemic circulation? 30mg. **Portion of oral dose that reaches systemic circulation.
Extraction Ration ER = [(Ci-Co)/Ci]. Ci:concentration in (the GI/portal system). Co:concentration out (of the GI/portal system). **First pass drugs have a high extraction ratio
Process by which most drugs cross membranes? Passive diffusion (moves down the concentration gradient). Therefore it must be dissolved and have sufficient lipid solubility (Inc lipid solubility = Faster diffusion). **Must be NON IONIZED to cross membrane
Partition Coefficient (passive drug diffusion) Dependent on lipid solubility. Represents the drug concentration ratio in lipid phase and water phase. Controlled by altering chemical side groupd. **PC = ([drug] in lipid phase)/([drug] in aqueous phase)
Higher PC means? Greater the rate of transfer of that drug across the membrane because a greater portion is already in the lipid phase.
Increased Ionization of a drug Decrease the rate at which it crosses the membrane due to increased polarity.
pH's effect on Ionization Most drugs are WEAK acids/bases which means there will usually be some of the drug in the ionized form. Weak acids: highly ionized in basic pH (better absorbed in the stomach). Weak bases: highly ionized in acidic pH (better absorbed in the Duodenum).
where will a drug with low pka be absrobed? high pka? low pka: stomach (less ionized because it will not want to donate an H+). high pka: Small intestine (less ionized). **When pH=pka, 50% ionized and 50% unionized
Henderson Hasselbalch Eq weak acid: pH=pKa+log(ionized/unionized). Weak Base: pH=pKa+log(unionized/ionized)
P-glycoprotein (MDR1) ABC transporter that works in cooperation with the liver after it makes drugs more ionized and aqueous. Usually found on luminal surface of: 1.Intestinal cells (w/ CYP3A4). 2.Hepatocyte mem. 3.Renal proximal tubular cell. 4.Brain endothelial cell.
Chemically Equivalent Contains the same amount of active ingredient but differs in bioavailability in that it will yield different plasma concentrations of active ingrediant over time.
Bioequivalent The rate and extent of absorption of a drug is not significantly different. (close to the same bioavailability).
Bioequivalent generic drugs Generic drugs do not have to do all the preclinical and clinical testing that Brand name drugs do b/c they are so close in bioavailability.
Important parameters measured in bioavailability studies 1.Minimal effective concentration (MEC). 2.Minimal toxic concentration (MTC). 3.Peak concentration Cmax (want this to be between the MEC and MTC). **Half-life is also taken into consideration
Created by: WeeG
Popular Pharmacology sets

 

 



Voices

Use these flashcards to help memorize information. Look at the large card and try to recall what is on the other side. Then click the card to flip it. If you knew the answer, click the green Know box. Otherwise, click the red Don't know box.

When you've placed seven or more cards in the Don't know box, click "retry" to try those cards again.

If you've accidentally put the card in the wrong box, just click on the card to take it out of the box.

You can also use your keyboard to move the cards as follows:

If you are logged in to your account, this website will remember which cards you know and don't know so that they are in the same box the next time you log in.

When you need a break, try one of the other activities listed below the flashcards like Matching, Snowman, or Hungry Bug. Although it may feel like you're playing a game, your brain is still making more connections with the information to help you out.

To see how well you know the information, try the Quiz or Test activity.

Pass complete!
"Know" box contains:
Time elapsed:
Retries:
restart all cards