Dietary Modification
A trial of dietary modification is a reasonable first choice in the treatment of the IBS. Patients should be encouraged to keep a diary of food intake and symptoms allowing the identification and exclusion of symptom-causing foods.
Dietary modification may be useful because most IBS
patients complain of symptom exacerbation after intake of
certain food groups.Some
patients may benefit from avoiding or limiting intake of
caffeine, alcohol, fatty foods, gas-producing vegetables, and/or
sorbitol-containing products such as sugarless gum and
dietetic candy.
Avoiding constipating foods and the addition
of fiber either in the diet or in the form of supplements,
such as bran, polycarbophil or a psyllium derivative,
equal to 20 to 30 g per day may be helpful in treating
patients with constipation. In patients with diarrhea, a trial
of a lactose free diet should be instituted in the event of a
concomittent lactase deficiency in addition to the IBS.
Treatment of pain in the IBS presents a great challenge.
Medications beneficial to one patient may be completely ineffectual
in another. Antispasmodics may reduce abdominal
pain via anticholinergic pathways or by direct relaxation of
smooth muscles with the use of nitrates and calcium channel
blockers.The latter two therapies may cause unintentional
hypotension and are, therefore, rarely prescribed for IBS.
Anticholinergics act by the antagonism ofmuscarinic receptors
innervated by the parasympathetic nervous system.
In addition to the desired effect of relaxation of smooth
muscle viscera, undesired effects, such as sedation, salivary
hyposecretion and urinary retention, can occur; this limits
the use of antispasmodics. Clinical trials of the anticholinergic
medications in the United States have been of
poor quality and are, therefore, difficult to evaluate.
Currently the following six antispasmodic/ anticholinergic
agents are available for use in the United States:
1. Dicyclomine (Bentyl)
2. Hyoscyamine sulfate (Levsin, Nulev, IBS Stat)
3. Methscopolamine bromide (Pamine)
4. Glycopyrrolate (Robinul)
5. Clidinium bromide chlordioxipoxide (Librax)
6. Belladonna with phenobarbital (Donnatal)