This interaction is based on this drug belonging to a drug class. While this drug may differ from the text and references below, drugs within this class work in a similar way and this interaction is applicable to drugs within the same class.

A study in animals has found that carbidopa inhibits an enzyme involved in the synthesis of niacin in the body. In addition, there is evidence that niacin synthesis is decreased in people taking carbidopa and other drugs in its class, raising the concern that people taking these drugs could be at risk of niacin deficiency, even if not frankly deficient. Further studies will be required determine if niacin supplementation is appropriate in people taking carbidopa.

A study in animals has found that carbidopa inhibits an enzyme involved in the synthesis of niacin in the body. In addition, there is evidence that niacin synthesis is decreased in people taking carbidopa and other drugs in its class. Further studies are needed to determine whether niacin supplementation is appropriate in people taking carbidopa.

A review of literature suggests that women who use oral contraceptives may experience decreased vitamin B1, B2, B3, B12, C, and zinc levels. Oral contraceptive use has been associated with increased absorption of calcium and copper and with increased blood levels of copper and vitamin A. Oral contraceptives may interfere with manganese absorption. The clinical importance of these actions remains unclear.

A review of literature suggests that women who use oral contraceptives may experience decreased vitamin B1, B2, B3, B12, C, and zinc levels. Oral contraceptive use has been associated with increased absorption of calcium and copper and with increased blood levels of copper and vitamin A. Oral contraceptives may interfere with manganese absorption. The clinical importance of these actions remains unclear.

A review of literature suggests that women who use OCs may experience decreased vitamin B1, B2, B3, B12, C, and zinc levels. OC use has been associated with increased absorption of calcium and copper and with increased blood levels of copper and vitamin A. OCs may interfere with manganese absorption. The clinical importance of these actions remains unclear.

A review of literature suggests that women who use OCs may experience decreased vitamin B1, B2, B3, B12, C, and zinc levels. OC use has been associated with increased absorption of calcium and copper and with increased blood levels of copper and vitamin A. OCs may interfere with manganese absorption. The clinical importance of these actions remains unclear.

A review of literature suggests that women who use oral contraceptives may experience decreased vitamin B1, B2, B3, B12, C, and zinc levels. Oral contraceptive use has been associated with increased absorption of calcium and copper and with increased blood levels of copper and vitamin A. Oral contraceptives may interfere with manganese absorption. The clinical importance of these actions remains unclear.

Isoniazid is capable of causing vitamin B3 (niacin) deficiency, most likely due to its ability to interfere with cell-repair enzymes made from niacin. Significant niacin deficiency, also known as pellagra, features dermatitis, diarrhea, and dementia (impaired intellectual function). Supplementation with vitamin B6 is thought to reduce this risk, although small amounts (e.g. 10 mg daily) has been noted to be inadequate in some cases.

A review of literature suggests that women who use oral contraceptives may experience decreased vitamin B1, B2, B3, B12, C, and zinc levels. Oral contraceptive use has been associated with increased absorption of calcium and copper and with increased blood levels of copper and vitamin A. Oral contraceptives may interfere with manganese absorption. The clinical importance of these actions remains unclear.

A review of literature suggests that women who use oral contraceptives may experience decreased vitamin B1, B2, B3, B12, C, and zinc levels. Oral contraceptive use has been associated with increased absorption of calcium and copper and with increased blood levels of copper and vitamin A. Oral contraceptives may interfere with manganese absorption. The clinical importance of these actions remains unclear.

A review of literature suggests that women who use oral contraceptives may experience decreased vitamin B1, B2, B3, B12, C, and zinc levels. Oral contraceptive use has been associated with increased absorption of calcium and copper and with increased blood levels of copper and vitamin A. Oral contraceptives may interfere with manganese absorption. The clinical importance of these actions remains unclear.

A review of literature suggests that women who use oral contraceptives may experience decreased vitamin B1, B2, B3, B12, C, and zinc levels. Oral contraceptive use has been associated with increased absorption of calcium and copper and with increased blood levels of copper and vitamin A. Oral contraceptives may interfere with manganese absorption. The clinical importance of these actions remains unclear.

Taking large amounts of niacinamide, a form of vitamin B3, can suppress inflammation in the body. According to numerous preliminary reports, niacinamide, given in combination with tetracycline or minocycline, may be effective against bullous pemphigoid, a benign, autoimmune blistering disease of the skin. Preliminary evidence also suggests a similar beneficial interaction may exist between tetracycline and niacinamide in the treatment of dermatitis herpetiformis.

Combination of 6 grams per day L-tryptophan and 1,500 mg per day niacinamide (a form of vitamin B3) with imipramine has shown to be more effective than imipramine alone for people with bipolar disorder. These levels did not improve the effects of imipramine in people with depression. Lower amounts (4 grams per day of L-tryptophan and 1,000 mg per day of niacinamide) did show some tendency to enhance the effect of imipramine.

The importance of the amount of L-tryptophan was confirmed in other studies, suggesting that if too much L-tryptophan (6 grams per day) is used, it is not beneficial, while levels around 4 grams per day may make tricyclic antidepressants work better.

Combination of 6 grams per day L-tryptophan and 1,500 mg per day niacinamide (a form of vitamin B3) with imipramine has shown to be more effective than imipramine alone for people with bipolar disorder. These levels did not improve the effects of imipramine in people with depression. Lower amounts (4 grams per day of L-tryptophan and 1,000 mg per day of niacinamide) did show some tendency to enhance the effect of imipramine.

The importance of the amount of L-tryptophan was confirmed in other studies, suggesting that if too much L-tryptophan (6 grams per day) is used, it is not beneficial, while levels around 4 grams per day may make tricyclic antidepressants work better.

Akathisia is an adverse reaction to anti-psychotic drugs, where a person has an uncontrollable desire to be in constant motion. One preliminary report suggested that 4,000 mg of L-tryptophan and 25 mg niacin per day taken with benztropine enhances the treatment of akathisia. Controlled studies are necessary to determine whether L-tryptophan and niacin supplements might benefit most people taking benztropine who experience adverse reactions to anti-psychotic drugs.

Combination of 6 grams per day L-tryptophan and 1,500 mg per day niacinamide (a form of vitamin B3) with imipramine has shown to be more effective than imipramine alone for people with bipolar disorder. These levels did not improve the effects of imipramine in people with depression. Lower amounts (4 grams per day of L-tryptophan and 1,000 mg per day of niacinamide) did show some tendency to enhance the effect of imipramine.

The importance of the amount of L-tryptophan was confirmed in other studies, suggesting that if too much L-tryptophan (6 grams per day) is used, it is not beneficial, while levels around 4 grams per day may make tricyclic antidepressants work better.

Combination of 6 grams per day L-tryptophan and 1,500 mg per day niacinamide (a form of vitamin B3) with imipramine has shown to be more effective than imipramine alone for people with bipolar disorder. These levels did not improve the effects of imipramine in people with depression. Lower amounts (4 grams per day of L-tryptophan and 1,000 mg per day of niacinamide) did show some tendency to enhance the effect of imipramine.

The importance of the amount of L-tryptophan was confirmed in other studies, suggesting that if too much L-tryptophan (6 grams per day) is used, it is not beneficial, while levels around 4 grams per day may make tricyclic antidepressants work better.

Niacin (not niacinamide) and gemfibrozil have successfully raised HDL (good) cholesterol levels, both alone and in combination.

Combination of 6 grams per day L-tryptophan and 1,500 mg per day niacinamide (a form of vitamin B3) with imipramine has shown to be more effective than imipramine alone for people with bipolar disorder. These levels did not improve the effects of imipramine in people with depression. Lower amounts (4 grams per day of L-tryptophan and 1,000 mg per day of niacinamide) did show some tendency to enhance the effect of imipramine.

The importance of the amount of L-tryptophan was confirmed in other studies, suggesting that if too much L-tryptophan (6 grams per day) is used, it is not beneficial, while levels around 4 grams per day may make tricyclic antidepressants work better.

Niacinamide taken in combination with minocycline has produced beneficial effects in an individual with cicatricial pemphigoid, an autoimmune blistering disease, as well as in a 46-year-old woman with pemphigus vegetans, another blistering disease. Several other studies have confirmed the efficacy of this combination for bullous (blistering) pemphigoid.

Combination of 6 grams per day L-tryptophan and 1,500 mg per day niacinamide (a form of vitamin B3) with imipramine has shown to be more effective than imipramine alone for people with bipolar disorder. These levels did not improve the effects of imipramine in people with depression. Lower amounts (4 grams per day of L-tryptophan and 1,000 mg per day of niacinamide) did show some tendency to enhance the effect of imipramine.

The importance of the amount of L-tryptophan was confirmed in other studies, suggesting that if too much L-tryptophan (6 grams per day) is used, it is not beneficial, while levels around 4 grams per day may make tricyclic antidepressants work better.

Combination of 6 grams per day L-tryptophan and 1,500 mg per day niacinamide (a form of vitamin B3) with imipramine has shown to be more effective than imipramine alone for people with bipolar disorder. These levels did not improve the effects of imipramine in people with depression. Lower amounts (4 grams per day of L-tryptophan and 1,000 mg per day of niacinamide) did show some tendency to enhance the effect of imipramine.

The importance of the amount of L-tryptophan was confirmed in other studies, suggesting that if too much L-tryptophan (6 grams per day) is used, it is not beneficial, while levels around 4 grams per day may make tricyclic antidepressants work better.

In a controlled study, individuals taking thioridazine for psychosis cooperated better and withdrew less from other people when niacin (nicotinic acid), 300–1,500 mg each day, was added. Whether people who are taking thioridazine for other mental health problems might benefit from niacin supplementation is unknown.

Combination of 6 grams per day L-tryptophan and 1,500 mg per day niacinamide (a form of vitamin B3) with imipramine has shown to be more effective than imipramine alone for people with bipolar disorder. These levels did not improve the effects of imipramine in people with depression. Lower amounts (4 grams per day of L-tryptophan and 1,000 mg per day of niacinamide) did show some tendency to enhance the effect of imipramine.

The importance of the amount of L-tryptophan was confirmed in other studies, suggesting that if too much L-tryptophan (6 grams per day) is used, it is not beneficial, while levels around 4 grams per day may make tricyclic antidepressants work better.