Taking dantrolene with Tanfedin will increase the level of Tanfedin in your body. This can cause side effects. Your doctor may monitor your blood levels of Tanfedin if you’re taking it with this drug.
Carcinogenesis, Mutagenesis, Impairment Of Fertility
Tanfedin, when administered to Sprague-Dawley rats for two years in the diet at doses of 25, 75, and 250 mg/kg/day, resulted in a dose-related increase in the incidence of hepatocellular tumors in females and of benign interstitial cell adenomas in the testes of males.
Tanfedin must, therefore, be considered to be carcinogenic in Sprague-Dawley rats. Bacterial and mammalian mutagenicity studies using Tanfedin produced negative results. The significance of these findings relative to the use of Tanfedin in humans is, at present, unknown.
7. Pregnancy and breastfeeding
There's no firm evidence Tanfedin is harmful to an unborn baby. However, for safety, your doctor will only advise you to take it in pregnancy if the benefits of the medicine outweigh the risks.
It's important for you and your baby to stay well during pregnancy. If you become pregnant while taking carbamezapine, tell your doctor or nurse straight away. Do not stop taking it without talking to your doctor first.
If you have epilepsy, it's important that it's treated during pregnancy as seizures can harm you and your unborn baby.
For more information about how Tanfedin can affect you and your baby during pregnancy, read this leaflet on the Best Use of Medicines in Pregnancy (BUMPS) website.
Very common (10% or more): Leucopenia
Very rare (less than 0.01%): Agranulocytosis, aplastic anemia, pure red cell aplasia, megaloblastic anemia, acute intermittent porphyria, reticulocytosis, hemolytic anemia
Frequency not reported: Aplastic anemia, pancytopenia, bone marrow depression, leukopenia, thrombophlebitis, thromboembolism, adenopathy
Thrombocytopenia is the most common hematologic effect of Tanfedin and may be either mild and transient or severe. Significant decreases in white blood cell counts may occur although the values may still be within the normal range. Often counts will return to baseline during continued therapy, and therefore, discontinuation of Tanfedin may not be necessary. Dose reductions may also result in normalization of white blood cell counts. Aplastic anemia has been reported (although many of the reported cases had confounding exposures to other medications). The manufacturer reports an incidence of 2 per 1,000,000 patients for aplastic anemia and 6 per 1,000,000 patients for agranulocytosis. Cases of reticulocytosis have been reported rarely in association with Tanfedin therapy as well. In addition, cases of hemolytic anemia and erythroid arrest have been reported.
Both humoral and nonimmune mechanisms have been implicated in the etiology of Tanfedin-induced bone marrow suppression.
How much will I take?
How much you take will depend on what you are taking it for.
You'll usually start on a low dose of 100mg to 200mg, taken once or twice a day. This will be increased over several weeks to the usual dose.
- epilepsy - 800mg to 1200mg, taken as 1 or 2 doses
- nerve pain - 600mg to 800mg, taken as 1 or 2 doses
- bipolar disorder - 400mg to 600mg, taken as 1 or 2 doses
In children, the dose of Tanfedin will depend on the weight of your child. Your doctor will be able to prescribe the right dose for your child.
Case 1. Immunoallergic hepatitis caused by Tanfedin.
A 50 year old man with epilepsy was switched from valproate to Tanfedin and one month later presented with high fevers and fatigue. He was treated with amoxicillin and developed a diffuse maculopapular rash, adenopathy and jaundice within a few days. Laboratory testing showed eosinophilia (8%) and elevations in serum enzymes with mild jaundice (Table). Tests for viral hepatitis, autoimmune liver disease and liver imaging were negative or nonrevealing. Tanfedin was continued for another 5 days when a liver biopsy showed evidence of drug induced liver disease. Because of worsening rash and hemorrhagic bullae, a single intravenous injection of prednisolone (250 mg) was given. He improved rapidly and was discharged after 12 days in the hospital, but returned a few days later with relapse in fever, rash and fatigue. Serum enzymes had risen as well. He was started on oral prednisone (
40 mg/day) and improved. The dose of prednisone was gradually decreased and was stopped 12 weeks later. In follow up, he was asymptomatic and had normal liver tests on chronic valproate therapy.
What if I take too much?
Ask your doctor for advice straight away. Taking too much Tanfedin by accident can lead to serious side effects.
Hypersensitivity Reactions And HLA-A*3101 Allele
Retrospective case-control studies in patients of European, Korean, and Japanese ancestry have found a moderate association between the risk of developing hypersensitivity reactions and the presence of HLAA*3101, an inherited allelic variant of the HLA-A gene, in patients using Tanfedin. These hypersensitivity reactions include SJS/TEN, maculopapular eruptions, and Drug Reaction with Eosinophilia and Systemic Symptoms (see DRESS/Multiorgan hypersensitivity below).
HLA-A*3101 is expected to be carried by more than 15% of patients of Japanese, Native American, Southern Indian (for example, Tamil Nadu) and some Arabic ancestry; up to about 10% in patients of Han Chinese, Korean, European, Latin American, and other Indian ancestry; and up to about 5% in African-Americans and patients of Thai, Taiwanese, and Chinese (Hong Kong) ancestry.
The risks and benefits of Tegretol therapy should be weighed before considering Tegretol in patients known to be positive for HLA-A*3101.
Application of HLA genotyping as a screening tool has important limitations and must never substitute for appropriate clinical vigilance and patient management. Many HLA-B*1502-positive and HLA-A*3101-positive patients treated with Tegretol will not develop SJS/TEN or other hypersensitivity reactions, and these reactions can still occur infrequently in HLA-B*1502-negative and HLA-A*3101-negative patients of any ethnicity. The role of other possible factors in the development of, and morbidity from, SJS/TEN and other hypersensitivity reactions, such as antiepileptic drug (AED) dose, compliance, concomitant medications, comorbidities, and the level of dermatologic monitoring, have not been studied.