Mrs. Clarke's physician prescribed two medications for her IBS. What are they and what is the proposed mechanism of each? She discusses the potential use of Lotronex if these medications do not help

Question

What is this medication and what is its mechanism? Identify any potential drug-nutrient interactions for these medications.

Answer 1

First medication: Elavil (25 mg daily)
i. Mechanism:
a. Antidepressant
b. Changes neurotransmitter levels in the brain, particularly serotonin-norepinephrine reuptake inhibitor. Since serotonin may have a role in IBS, changes in serotonin levels resulting from use of this medication may have a secondary effect on IBS.
ii. Drug-nutrient interactions:
a. Cannot take with alcohol; should tell doctor if you drink an excessive amount of alcohol
b. Cannot take with MAOIs
c. Cannot take with epinephrine (may cause high blood pressure)
d. Changes in appetite
e. Constipation
f. Nausea
g. Vomiting
h. Avoid St. John's Wort
i. Avoid excessive amounts of caffeine
Second medication: Metamucil (1 T in 8 oz. of liquid twice daily)
i. Mechanism: Laxative, psyllium bulking agent; soluble fiber forms gel in the colon, retains water, and increases peristalsis.
ii. Drug-nutrient interactions:
a. Diarrhea, cramping
b. Malabsorption of nutrients due to decreased transit time
Lotronex:
i. Mechanism:
a. Specifically for women whose main IBS problem is diarrhea
b. Used to treat diarrhea, pain, cramps, and the feeling of an urgent need to have bowel movements caused by irritable bowel syndrome
c. Serotonin-antagonist. Blocks 5-HT3 serotonin receptor to decrease action of serotonin, reduce abdominal pain, and change motility of the intestine.
d. The indication is restricted to those patients for whom the benefit-to-risk balance is most favorable (may cause severe constipation or ischemic colitis).
ii. Drug-nutrient interactions:
a. Avoid eating grapefruit or grapefruit juice
b. Constipation