Term
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Definition
•Is the movement of drug down the concentration
gradient
•It is an un-saturable process, does not require energy
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Term
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Definition
Drug movement is down the concentration gradient but requires a carrier. It is a saturable process
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Term
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Definition
•Movement occurs against the concentration gradient and needs energy like ATP. It is a saturable process
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Term
| What important factors affect the absorption of a drug across a membrane? |
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Definition
•Lipid solubility / Water solubility
•pH/ Nature of the drug?
•The pH levels on either side of cell membrane
•pKa of the drug
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Term
| Water soluble/ hydrophilic.. |
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Definition
| The ionised or electrically charged form of a drug and it …CANNOT cross membrane, thus it is fit for excretion. |
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Term
| Lipid-soluble/ lipophiilic |
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Definition
| is the non ionised, or uncharged form….Can cross membrane, thus is fit for absorption. |
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Term
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Definition
a weak acid will become more and more unionized, thus lipid soluble and better absorbed
a weak base will become more and more ionized ,thus lipid insoluble, and will not be absorbed. (Also becomes more water soluble and better excreted) .
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Term
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Definition
a weak acid will become more and more ionised,thus lipid insoluble and will not be absorbed. (Also becomes more water soluble and better excreted).
a weak base will become more and more unionized , thus lipid soluble and better absorbed. |
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Term
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Aspirin is an acidic drug. What will happen to it in the stomach and why.. what will be contraindicated when taking it?
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Definition
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Acidic drugs in acidic environments are unionised, thus lipid soluble and can cross membrane
For better absorption take on empty stomach… plus no antacid to be taken as this will decrease the acidity of the environment.
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Term
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Definition
| is equivalent to the pH at which 50% drug is ionized and 50% is unionized |
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Term
In what circumstance would you need to acidify urine?
How can this be accomplished? |
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Definition
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In basic drug poisoning (i.e atropine & chloroquine), as this would make the base more ionised and better excreted.
–Give Ammonium chloride or Vitamin C or Cranberry juice
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Term
In what circumstance would you need to make urine more alkali?
How can this be achieved?
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Definition
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in acidic drug poisoning (ie phenobarbitone), thus making it more ionised and better excreted.
–Give Sodium bicarbonate or Acetazolamide
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Term
| What are the barriers a drug must go through before it reaches circulation? |
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Definition
1. Broken down in intestine/ GI
2. Some is excreated, other part travels though intestinal wall
3. Broken down in intestinal wall and sent via portal vein to liver
4. Broken down in liver.. then remaining part reaches systemic circulation |
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Term
What is Bioavaliability?
How is it calculated? |
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Definition
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The fraction of the administered
dose reaching the systemic circulation in its chemically unchanged form. Designated as “ F ”
F = AUCoral / AUCiv
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Term
| What id First pass metabolism? Give an example if a drug which shows it and how this is overcome. |
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Definition
It is the fraction of lost drug during the process of absorption which is generally related to the liver and gut wall.
Lidocaine & nitrogylcerine shows this, and it is overcome by administering it through an IV (this route has 100% bioavaliability). |
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Term
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Definition
•Two different brands (brand A and B) of a same drug give orally to the same person
•If they differ in bioavailibility and rate of absorption …both brand A and B are said to be Bioinequivalent…..this is common
•If they have same bioavailibility and rate of absorption …both brand A and B are said to be Bioequivalent…..this is uncommon
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