Thiamine is specifically used in the treatment of the various manifestations of thiamine deficiency such as Beriberi and Wernick's encephalopathy, neuritis associated with pregnancy and pellagra. Supplementary Thiamine may be indicated prophylactically in conditions where there is low dietary intake or impaired gastro intestinal absorption of thiamine (e.g. alcohol) or where requirements are increased (pregnancy, carbohydrate rich diet).

Vitamin-B preparations

Thiamine, in the form of thiamine pyrophosphate, is the coenzyme for decarboxylation of α-ketoglutaric acid. Thiamine deficiency affects the peripheral nervous system, the gastrointestinal tract, and the cardiovascular system. This vitamin is necessary for the optimal growth of infants and children. Thiamine is not stored in the body, and is regularly lost from tissues during short periods of deficiency. In order to maintain normal health, an adequate amount of thiamine is required every day. Deficiency of thiamine leads to fatigue, anorexia, gastrointestinal disturbance, tachycardia, irritability and neurological symptoms. Beriberi, a disease due to vitamin B1 deficiency, is common in alcoholics, in pregnant women receiving an inadequate diet, and in people with malabsorption syndrome, prolonged diarrhoea and hepatic disease. Thiamine is well absorbed from the gastrointestinal tract and widely distributed throughout the body. Thiamine is rapidly absorbed from the upper small intestine. Thiamine is not stored in the body to any appreciable extent. Excess ingested thiamine appears in urine as intact thiamine or as pyrimidine, which arises from degradation of the thiamine molecule. The plasma half life of thiamine is 24 hours.

Prophylaxis: 3 to 10 mg daily. Mild chronic deficiency: 10 to 25 mg daily. Severe deficiency: 200 to 300 mg daily.

No hazardous drug interactions have been reported. Vitamin B1 acts synergistically with other vitamins of the B-complex group and its potential for causing adverse effects is considerably reduced.

There is no absolute contraindication but the risk of anaphylaxis is increased by repeated parenteral administration. Mild allergic phenomena, such as sneezing or mild asthma are warning signs that further may give rise to anaphylactic shock. To avoid this possibility it is advisable to start a second course of injection with a dose considerably lower than that previously used. Because of the above, vitamin B1 injection should not be given intravenously except in the case of comatose patients. Once thiamine deficiency is corrected there is no need for parenteral administration or for the administration of amounts in excess of daily requirement.

Vitamin B1 does not have adverse effects when given orally, but in a few fatal cases anaphylactic reactions have occurred after intravenous administration of large doses (400 mg) in sensitive patients, especially children, and in one case following an intramuscular dose of 125 mg. The risk of such reactions increases with repeated administration of the drug by parenteral route. Transient mild soreness may occur at the site of intramuscular administration

The drug may be given safely to neonates, children, pregnant and lactating women and elderly patients.

Thiamine injection should be protected from light and moisture.