Term
What is the surface area of the rectum?
How is its structure different from the colon?
How much blood from the rectum undegoes 1st pass effect?
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Definition
Small ~ 200-400 cm2
Doesn't have villi or microvilli, smaller surface area than the small intestine
only 1/3 goes to the liver |
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Term
T/F
It's recommended to use an enema prior to administration of a rectal suppository |
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Definition
TRUE
Greater absorption from a voided colon |
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Term
What is the pH of the rectum?
What is its buffer capacity? |
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Definition
pH 7-8
Low buffer capacity (not resistant to changes in pH) |
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Term
| How do you calculate buffer capacity? |
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Definition
Buffer= increment of base/acid added
pH change |
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Term
| What drug properties affect systemic absorption of rectal suppositories? |
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Definition
Partition Coefficient
Ionization, pKa |
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Term
T/F
Chances of irritation increase with rectal suppositories due to a lack of buffer
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Definition
TRUE
Rectum has low buffer capacity |
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Term
| What is pegulation and what role does it play? |
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Definition
Adding PEG molecules to proteins to improve stability and 1/2 life
(Polyethylene Glycol) |
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Term
T/F
Cocoa Butter has two polymorhps and the alpha form is the more desirable of the 2 |
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Definition
FALSE
Beta is better b/c it melts ~35 C and it more stable
alpha melts <30 C and is bad for storage |
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Term
| How do you avoid getting the alpa form of Cocoa Butter |
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Definition
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Term
T/F
Water-soluble bases are more common than oleaginous bases for rectal suppositories |
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Definition
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Term
| How do you calculate the volume of the base needed to make the suppository? |
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Definition
Vol of base= Vol of mold-Vol of drug
(calculate vol from density)
m/v=d |
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