Lactose Intolerance and Its Most Common Drug List

Introduction

Lactose intolerance is a disorder in which a person is unable to digest lactose, which is a sugar found in milk and its products, including breast milk. Our small intestines produce an enzyme called lactase which breaks down lactose into simpler sugars galactose and glucose which are absorbed into our bloodstream and utilized by our body. In people with lactose intolerance there is a deficiency of the enzyme lactase which leads to malabsorption of lactose in the body. These people produce very low levels of lactase and hence are unable to completely digest lactose. The undigested lactose reaches the colon, where it is acted upon by the bacteria, leading to production of unpleasant fluid and gas. However, not all people with lactase deficiency and lactose malabsorption develop digestive symptoms like bloating, gas and diarrhea after consuming milk and milk products.

Lactase enzyme levels are highest shortly after birth and almost everyone has the ability to digest breast milk. Lactose intolerance is seldom observed in children below the age of 5 years. The ability to digest lactase keeps on decreasing as we age, in-spite of regular consumption of lactose. Most of the animals also lose their ability to digest lactose on reaching adulthood. Asian, African and South American populations are susceptible to developing lactase deficiency. However, races of northwestern Indian subcontinent and Europe are more likely to retain their ability to digest lactose in their adulthood.
Evidence suggests that lactose intolerance is an extremely common condition which affects nearly 75% people globally. It is not a serious condition and can be easily managed by most of the people.

Lactose intolerance should not be confused with milk allergy in which the immune system reacts to one or more of the milk proteins. It can become life threatening if the person consumes even a small amount of milk or its product. Milk allergy is usually detected within the first year of life, whereas lactose intolerance develops more commonly during adolescence or adulthood.

Symptoms

Symptoms of lactose intolerance develop in 30 minutes to 2 hours after consuming milk and its products. The severity of symptoms depends on the amount of lactose ingested, and the amount a person can tolerate. Lactose intolerance disorder does not cause any damage to the gastrointestinal tract but can produce some disturbing symptoms. Some of the commonly observed symptoms of lactose intolerance are:

• Abdominal bloating
• Abdominal pain
• Gas
• Diarrhea
• Nausea

Treatment

Lactose intolerance has no cure but the patient can manage his symptoms by limiting his intake of milk and milk products. Some people might be required to avoid lactose altogether. If there is an underlying cause that is resulting in lactose intolerance like, injury, celiac disease, Crohn’s disease and bacterial overgrowth, treating it can help in improving symptoms. Disorder arising due to genetic reasons has no cure.

Lactase, an enzyme which can be industrially produced by fungi belonging to genus Aspergillus , can be used for managing the symptoms. Another enzyme, β-galactosidase is available in a variety of doses that can help in managing the symptoms of lactose intolerance. However, it should be noted that these enzymes are not approved by the U.S. FDA.

Sometimes, increasing the exposure to lactose can help the body in adapting to it. This study is still in its initial phase and requires more extensive evaluation.

Some studies have also indicated that consumption of probiotics and prebiotics can also help in improving the symptoms of lactose intolerance. Bifidobacteria, which is often found in probiotic yogurts and supplements, is one such probiotic that has been found to be useful in this disorder.

People with Lactose intolerance are at a high risk of developing calcium and vitamin D deficiency as milk and milk products are one of their richest sources. These people should take calcium and vitamin D supplements to meet their requirement of calcium and vitamin D.

1. Vitamin D supplements

Vitamin D and calcium are necessary for maintaining bone health, which can be obtained through different sources. There are two types of vitamin D, namely D2 and D3. Vitamin D2 (ergocalciferol or calciferol) is obtained from dietary sources, whereas vitamin D3 (cholecalciferol) is synthesized in skin in the presence of UV rays from the sun. Both D2 and D3 enter into our liver and kidneys, where these are converted into the active form of vitamin D, calcitriol, which is responsible for increasing calcium absorption in intestine.

Available as: Oral preparations and Injectable preparations

I. Vitamin D2 (Ergocalciferol)
U.S. FDA Status: Approved
Generic name: ergocalciferol
Brand name: Drisdol capsule
Side-effects: Increased frequency of urination, increased blood pressure, increased thirst and mental retardation
Indicated in pregnancy: No, until benefit outweighs fetal risk.
Alcohol content: Absent

II. Doxercalciferol
It is a synthetic analogue of vitamin D2 (ergocalciferol).

U.S. FDA Status: Approved
Availability: Prescription only
Generic name: doxercalciferol
Brand name: Hectorol capsule; Doxercalciferol injections
Side-effects: Irregular heartbeat, hives, difficulty breathing, abdominal pain, rash
Indicated in pregnancy: No, until benefit outweighs fetal risk
Alcohol content: Absent

III. Dihydrotachysterol
It is another synthetic analogue of vitamin D2, which gets converted into activated form of vitamin D in the liver and not kidneys.

U.S. FDA Status: Unapproved
Availability: Discontinued
Generic name: dihydrotachysterol
Brand name: DHT tablet
Side-effects: Headache, anorexia, vomiting, constipation, nausea
Indicated in pregnancy: Only if absolutely indicated
Alcohol content: Absent

IV. Vitamin D3 (Cholecalciferol)
U.S. FDA Status: Approved
Availability: Over-the-counter
Generic name: cholecalciferol
Brand name: Cholecalciferol
Side-effects: Poor appetite, nausea, vomiting, cough, dizziness, hives
Indicated in pregnancy: No, until benefit outweighs fetal risk
Alcohol content: Absent

V. Calcitriol
It is the active form of vitamin D and is beneficial for people with liver or kidney failure.

Calcitriol Oral

U.S. FDA Status: Approved
Availability: Prescription only
Generic name: calcitriol
Brand name: Rocaltrol capsule
Side-effects: Nausea, weakness, headache, constipation, muscle or bone pain, metallic taste
Indicated in pregnancy: No, until benefit outweighs fetal risk
Alcohol content: Absent

Calcitriol Injection

U.S. FDA Status: Unapproved
Availability: Discontinued
Generic name: calcitriol
Brand name: Calcijex intravenous injection
Side-effects: Constipation, nausea, vomiting, agitation, abdominal cramps
Indicated in pregnancy: No, until benefit outweighs fetal risk
Alcohol content: Absent

VI. Paricalcitol
It is a synthetic analogue of calcitriol, which is prescribed to patients with kidney disorders.

U.S. FDA Status: Approved
Availability: Prescription only
Generic name: paricalcitol
Brand name: Zemplar intravenous solution (injection); Zemplar capsule (oral)
Side-effects: Blurred vision, cough, difficulty with swallowing, headache
Indicated in pregnancy: No, until absolutely required
Alcohol content: Absent

VII. Alfacalcidol
It is a vitamin D analogue which is converted into active form of vitamin D, calcitriol, in the liver. Since, it does not get activated in kidney, it can be safely prescribed to patients with kidney disorder. Although it gets activated in the liver, it can still be taken in patients with severe liver disorders.

U.S. FDA Status: Unapproved
Availability: Discontinued
Generic name: alfacalcidol
Brand name: Alfacalcidol
Side-effects: Constipation, dry mouth, feeling thirsty, frequent urination
Indicated in pregnancy: No, until benefit outweighs fetal risk
Alcohol content: Absent

3. Calcium Supplements

People with lactose intolerance often develop calcium deficiency as they are unable to consume milk and milk products, one of the richest sources of calcium. They can replenish the calcium reserves of their body by taking calcium supplements.

Available as: Oral preparations

I. Calcium Carbonate
It is used for increasing the blood calcium levels in people with calcium deficiency.

U.S. FDA Status: Not authorized to approve
Availability: Over-the-counter
Generic name: calcium carbonate
Brand name: Caltrate
Side-effects: Hives, itching, peeling skin, trouble breathing, wheezing, fever
Indicated in pregnancy: Can be taken in recommended dosages
Alcohol content: Absent

II. Calcium Citrate
U.S. FDA Status: Not authorized to approve
Availability: Over-the-counter
Generic name: calcium citrate
Brand name: Citracal
Side-effects: Decreased urination, rapid weight gain, nausea, constipation, vomiting
Indicated in pregnancy: No, until absolutely required
Alcohol content: Absent

Symptomatic Treatment

a. Diarrhea
Lactose intolerance often results in diarrhea, which is different from the diarrhea generally occurring due to gastric infection. In the latter form of diarrhea, it is the body’s way of getting rid of the infection and hence is recommended to run its course. However, diarrhea occurring in lactose intolerance is due to digestive problem and therefore, can be treated with antidiarrheals.

I. Loperamide
U.S. FDA Status: Approved
Availability: Over-the-counter
Generic name: loperamide hyudrochloride
Brand name: Imodium A-D
Side-effects: Skin rash, dizziness, dryness of mouth, constipation, headache, flatulence and nausea
Indicated in pregnancy: No, unless benefit outweigh risks
Alcohol content: Absent

II. Bismuth subsalicylate
U.S. FDA Status: Unapproved
Availability: Over-the-counter
Generic name: bismuth subsalicylate
Brand name: Bismarex
Side-effects: Anxiety, severe constipation, dizziness, headache, depression, nausea, severe stomach pain and fast breathing
Indicated in pregnancy: Only if absolutely indicated
Alcohol content: Absent

b. Abdominal Bloating and Gas
For treating abdominal bloating and gas, ant flatulent drugs can be used. They act on the stomach and intestines and change the surface tension of gas bubbles, thereby facilitating their breakdown and formation of larger bubbles. In this way, extra gas can be easily eliminated from the body more easily by belching or passing flatus.

I. Simethicone
U.S. FDA Status: Unapproved
Availability: Over-the-counter
Generic name: simethicone
Brand name: Anti-Gas Ultra Strength
Side-effects: No known side effects
Indicated in pregnancy: Yes
Alcohol content: Absent

OTC Drugs Used

Based on differing criteria of drug regulatory bodies of different countries, the over-the-counter availability of drugs varies. Although Lactose intolerance cannot be cured, there are certain drugs available for managing its symptoms. Usually, a low dose of vitamin D is available as an over-the-counter supplement, whereas a higher dose would require a prescription. The various OTC drugs that can be used for managing the symptoms of lactose intolerance have been summarized in the table below.