Stoma output can be controlled by anti-motility drugs such as loperamide and codeine.

Excessive intake of liquids in stoma patients can lead to sodium depletion and dehydration. Patients with a high output should limit the use of hypotonic liquids, and used oral rehydration solution.

After surgery the bowel will usually have a reduced ability to absorb nutrients. The can be at risk of re-feeding syndrome when feeds are introduced (Re-feeding syndrome can be defined as the potentially fatal shifts in fluids and electrolytes that may occur in malnourished patients receiving artificial re-feeding).

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DEFICIENCIES THAT AFFECT PATIENTS:

• Vitamin B deficiency (thiamine B1): Thiamine is an essential co-enzyme in carbohydrate metabolism and deficiency can lead to dangerous electrolyte disturbances when carbohydrates are reintroduced. IV doses can be given in high risk cases, and an oral dose may also be administered.

• Hypomagnesaemia: increased chelation of magnesium with absorbed fatty acids in the bowel, and increases Mg loss via the stoma causes this. It is an important co-factor for enzymatic reactions and helps maintain normal central nervous system activity. Also the co-factor for the Na/K ATPase pump. Oral supplements are usually given, but diarrhoea is a common side effect.

• ​Hypoalbuminaemia: Absorption of dietary proteins may be impaired as a result of the underlying bowel disease or the formation of a stoma. Albumin levels can fall amd this can result in increased plasma concentrations of highly protein-bound drugs, such as warfarin and phenytoin.

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PHARMACOKINETIC ISSUES

Absorption: Modified-release or enteric coated medicines should be used with caution, and in most cases avoided.

The active ingredient may not be at the site of absorption long enough, or can bypass it completely.

The use of medicine that cause a laxative effect should be avoided, such as those containing the excipient sorbitol.

PPIS are often used in stoma patients, which can increase the PH of the stomach, therefore drugs that need to be in an acidic environment to be absorbed (such as levothyroxine) can be less effective, and may need a dose increase.

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Distribution: High stoma output can cause dehydration, and lower the volume of distribution of water-soluble drugs. Drugs with a narrow therapeutic window (digoxin, gentamicin)

 

​Metabolism: Stoma patients can become chronically malnourished and the reduced absorption and synthesis of proteins can affect drug metabolism. There is less protein being broken down into amino acids, therefore fewer able to from enzymes for drug metabolism.

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Excretion: dehydration in stoma patients can lead to renal dysfunction, and clearance of drugs can be reduced.