FOLATE REGULATION

The term "folate" are B vitamins that include folic acid and any forms of active pteroylglutamates regardless of the reduction state of the molecule. Folates, or vitamin B9, are primarily hydrolyzed in the intestinal jejunum and the liver to the active circulating form of folate, l-methylfolate, with an intermediate stable form, 5,10-methylenetetrahydrofolate.

Individuals with genetic polymorphisms for the genes coding methylenetetrahydrofolate reductase (MTHFR) may not be capable of utilizing or metabolizing folic acid adequately for the vitamin B12 dependent methylation cycle.

Folic acid, including reduced forms1 such as folinic acid, may obscure pernicious anemia above 0.1 mg doses, and must be administered under the supervision of a licensed medical practitioner.

The 1971, 1972, 1973, 1980, 1984, 2000, and 2010 Federal Register Notices addressed this concern while establishing that increased folate was proper therapy in megaloblastic anemias - specifically where homocysteine levels were elevated or risk of neural tube defects (NTDs) was at issue. The Federal Register Notice of August 2, 1973 (38 FR 20750) specifically states that:

Dietary supplement preparations are available without a prescription (21 CFR 121.1134). Levels higher than dietary supplement amounts are available only with a prescription.

Folic acid - including reduced forms, may be added to medical foods as defined in section 5(b)(3) of the Orphan Drug Act (21 USC 360ee(b)(3)), or to food (21 CFR 172.345).

1

It is not known whether or not l-methylfolate can obscure pernicious anemia above 0.1 mg doses, so caution is advised also with this form of folate.

WARNING

Ingestion of more than 3 grams of omega-3 fatty acids per day has been shown to have potential antithrombotic effects, including an increased bleeding time and INR. Administration of omega-3 fatty acids should be avoided in patients on anticoagulants and in those known to have an inherited or acquired bleeding diathesis.

General

Folate, when administered as a single agent in doses about 0.1 mg daily, may obscure the detection of vitamin B12 deficiency (specifically, the administration of folic acid may reverse the hematological manifestations of B12 deficiency, including pernicious anemia, while not addressing the neurological manifestations). Folate therapy alone is inadequate for treatment of a vitamin B12 deficiency.

CAUTION

Exercise caution to ensure that the prescribed dosage of DHA does not exceed 1 gram (1000 mg) per day.

PATIENT INFORMATION

VP-CH-PNV is a PRENATAL/POSTNATAL prescription folate / obstetrics medical food to be used only under licensed medical supervision.

DRUG INTERACTIONS

Drugs which may interact with folate2 include:

• Antiepileptic drugs (AED): The AED class including, but not limited to, phenytoin, carbamazepine, primidone, valproic acid, fosphenytoin, valproate, phenobarbital and lamotrigine have been shown to impair folate absorption and increase the metabolism of circulating folate.
• Additionally, concurrent use of folic acid has been associated with enhanced phenytoin metabolism, lowering the level of the AED in the blood and allowing breakthrough seizures to occur. Caution should be used when prescribing this product among patients who are receiving treatment with phenytoin and other anticonvulsants.
• Capecitabine: Folinic acid (5-formyltetrahydrofolate) may increase the toxicity of capecitabine.
• Cholestyramine: Reduces folic acid absorption and reduces serum folate levels.
• Colestipol: Reduces folic acid absorption and reduces serum folate levels.
• Cycloserine: Reduces folic acid absorption and reduces serum folate levels.
• Dihydrofolate Reductase Inhibitors (DHFRI): DHFRIs block the conversion of folic acid to its active forms, and lower plasma and red blood cell folate levels. DHFRIs include aminopterin, methotrexate, pyrimethamine, triamterene, and trimethoprim.
• Fluoxetine: Fluoxetine exerts a noncompetitive inhibition of the 5-methyltetrahydrofolate active transport in the intestine.
• Isotretinoin: Reduced folate levels have occurred in some patients taking isotretinoin.
• L-dopa, triamterene, colchicine, and trimethoprim may decrease plasma folate levels.
• Nonsteroidal Anti-inflammatory Drugs (NSAIDs): NSAIDs have been shown to inhibit some folate dependent enzymes in laboratory experiments.
• NSAIDs include ibuprofen, naproxen, indomethacin and sulindac.
• Oral Contraceptives: Serum folate levels may be depressed by oral contraceptive therapy.
• Methylprednisolone: Reduced serum folate levels have been noted after treatment with methylprednisolone.
• Pancreatic Enzymes: Reduced folate levels have occurred in some patients taking pancreatic extracts, such as pancreatin and pancrelipase.
• Pentamidine: Reduced folate levels have been seen with prolonged intravenous pentamidine.
• Pyrimethamine: High levels of folic acid may result in decreased serum levels of pyrimethamine.
• Smoking and Alcohol: Reduced serum folate levels have been noted.
• Sulfasalazine: Inhibits the absorption and metabolism of folic acid.
• Metformin treatment in patients with type 2 diabetes decreases serum folate.
• Warfarin can produce significant impairment in folate status after a 6-month therapy.
• Heme-iron: Can compete for transport and reduce folate absorption.
• Folinic acid may enhance the toxicity of fluorouracil.
• Concurrent administration of chloramphenicol and folinic acid in folate-deficient patients may result in antagonism of the haematopoietic response to folate.
• Caution should be exercised with the concomitant use of folinic acid and trimethoprim-sulfamethoxazole for the acute treatment of Pneumocystis carinii pneumonia in patients with HIV infection as it is associated with increased rates of treatment failure and mortality in a placebo controlled study.

Drugs which interact with vitamin B6:

• Vitamin B6 should not be given to patients receiving the drug levodopa because the action of levodopa is antagonized by vitamin B6. However, vitamin B6 may be used concurrently in patients receiving a preparation containing both carbidopa and levodopa.
• Isoniazid can produce a vitamin B6 deficiency.

Drugs which may interact with vitamin D3:

• Certain thiazide diuretics, such as hydrochlorothiazide, as well as antacids, bile acid sequestrants (such as cholestyramine), mineral oil, orlistat, olestra, cimetidine, and anticonvulsant medications may reduce the absorption or increase the catabolism of vitamin D.
• Vitamin D supplementation should not be given with calcium in those with hypercalcemia or conditions that may lead to hypercalcemia such as hyperparathyroidism and those who form calcium-containing kidney stones.

2

Folate is a broad term that includes folic acid and all reduced forms including l-methylfolate and folinic acid. VP-CH-PNV does not contain l-methylfolate or folinic acid but these warnings are included as general folate information.

PREGNANCY and NURSING MOTHERS

VP-CH-PNV is intended for use before, during and after pregnancy for lactating and non-lactating mothers. Talk with your medical practitioner to ensure adequate prenatal/postnatal supplementation.