biochem 3h03
Pg. 25
Once drug goes into mucosal cells, the concentration gradient will decrease.
Blood supply to mucosal cell keeps removing drug continuously so the drug conc is smaller & this (heavy vascularisation) maintains constant gradient so that the drugs are constantly removed into the blood stream
pH in stomach about 2
Implication: weak acids absorbed readily, weak bases not absorbed as readily
Implication: some of the drugs may not be able to suvive that acidic environment. & they may disintegrate in that environment. For sch drugs, stomach may not be suitable.
Pepsin and Trypsin = enzymes which break down peptides (they are proteases)
Trypsin will chop off the proteins after basic amino acids & pepsin will chop them more after the hydrophobic amino acids.
If going to take a peptide, add a protein orally – that’`s not going to be that useful béc that peptide could be broken down in the stomach.
Drug that`s a protein or peptide = Insulin
Insulin is a small protein. Therefore cannot take orally (this route not suitable for this drug)
Pg. 26
Absorption of weak acids in the stomach is rapid
Rate of absorption = faster for weak acids more than weak bases!ÉÉ!
Total absorption = rate o..!É!
Drug will spend up to an hour in stomach if taken with food. However, If taken in empty stomach it`ll take no more htan 10 mins. Therefore, total amount absorbed in stomach will vary. Sometimes want to drug to absorb therefore rapid absorption. Sometimes don’t want the drug to stay in stomach for long time or else will be degraded there. Therefore, sometimes will say to take a drug in full stomach or not to take a durg in a full stomach.
Clarify:
Amount of absorption = rate x time
Aborption to occur in stomach – take in full stomach (drug stay a long time in stomach)
Drug will disintegrate in low pH then don’t want drug to stay in the stomach for a long time.
Pg. 27
Once drug not absorbed in stomach, it moves into intestines.
Small intestine. The
Once drug goes into mucosal cells, the concentration gradient will decrease.
Blood supply to mucosal cell keeps removing drug continuously so the drug conc is smaller & this (heavy vascularisation) maintains constant gradient so that the drugs are constantly removed into the blood stream
pH in stomach about 2
Implication: weak acids absorbed readily, weak bases not absorbed as readily
Implication: some of the drugs may not be able to suvive that acidic environment. & they may disintegrate in that environment. For sch drugs, stomach may not be suitable.
Pepsin and Trypsin = enzymes which break down peptides (they are proteases)
Trypsin will chop off the proteins after basic amino acids & pepsin will chop them more after the hydrophobic amino acids.
If going to take a peptide, add a protein orally – that’`s not going to be that useful béc that peptide could be broken down in the stomach.
Drug that`s a protein or peptide = Insulin
Insulin is a small protein. Therefore cannot take orally (this route not suitable for this drug)
Pg. 26
Absorption of weak acids in the stomach is rapid
Rate of absorption = faster for weak acids more than weak bases!ÉÉ!
Total absorption = rate o..!É!
Drug will spend up to an hour in stomach if taken with food. However, If taken in empty stomach it`ll take no more htan 10 mins. Therefore, total amount absorbed in stomach will vary. Sometimes want to drug to absorb therefore rapid absorption. Sometimes don’t want the drug to stay in stomach for long time or else will be degraded there. Therefore, sometimes will say to take a drug in full stomach or not to take a durg in a full stomach.
Clarify:
Amount of absorption = rate x time
Aborption to occur in stomach – take in full stomach (drug stay a long time in stomach)
Drug will disintegrate in low pH then don’t want drug to stay in the stomach for a long time.
Pg. 27
Once drug not absorbed in stomach, it moves into intestines.
Small intestine. The