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Molybdenum Supplements (Systemic)

Primary: TN499

Commonly used brand name(s): Molypen.

Note: For a listing of dosage forms and brand names by country availability, see Dosage Forms section(s).

Not commercially available in Canada.


Nutritional supplement (mineral)—



Molybdenum deficiency (prophylaxis and treatment)—Molybdenum is indicated in the prevention and treatment of molybdenum deficiency, which is rare but {11} may result from inadequate nutrition or intestinal malabsorption. Molybdenum deficiency does not occur in healthy individuals receiving an adequate balanced diet. For prophylaxis of molybdenum deficiency, dietary improvement, rather than supplementation, is advisable. For treatment of molybdenum deficiency supplementation is preferred. {15}
—Deficiency of molybdenum is rare, but when it occurs it may lead to an intolerance of sulfur-containing amino acids. {03} {05}
—Some unusual diets (e.g., reducing diets that drastically restrict food selection) may not supply minimum daily requirements of molybdenum. Supplementation may be necessary in patients receiving total parenteral nutrition (TPN) {05} or undergoing rapid weight loss or in those with malnutrition, because of inadequate dietary intake.


Physicochemical characteristics:
Molecular weight—
    Ammonium molybdate: 1235.86 {07}
    Elemental molybdenum: 95.94 {03}

Mechanism of action/Effect:

Molybdenum is a component of the enzymes xanthine oxidase, sulfite oxidase, and aldehyde oxidase. These enzymes are responsible for conversion of xanthine and hypoxanthine to uric acid, conversion of sulfite to sulfate, and detoxification of several harmful organic molecules, respectively. {01}


Dietary molybdenum is well absorbed in the gastrointestinal tract. {03}


Molybdenum is stored in the liver, kidneys, spleen, lung, brain, and muscles. {03}

    Primarily in urine, with small amounts excreted in bile. {01}

Precautions to Consider


Studies have not been done in humans and problems have not been documented with intake of normal daily recommended amounts.

Studies have not been done in animals.

FDA Pregnancy Category C (parenteral molybdenum). {01}


Problems in humans have not been documented with intake of normal daily recommended amounts.


Problems in pediatrics have not been documented with intake of normal daily recommended amounts.


Problems in geriatrics have not been documented with intake of normal daily recommended amounts.

Drug interactions and/or related problems
The following drug interactions and/or related problems have been selected on the basis of their potential clinical significance (possible mechanism in parentheses where appropriate)—not necessarily inclusive (» = major clinical significance):

Note: Combinations containing any of the following medications, depending on the amount present, may also interact with this medication.

Copper supplements    (excessive amounts of molybdenum may mobilize copper from tissue and increase urinary excretion of copper {01} {06}; copper supplements may be recommended with molybdenum therapy {09})

Medical considerations/Contraindications
The medical considerations/contraindications included have been selected on the basis of their potential clinical significance (reasons given in parentheses where appropriate)— not necessarily inclusive (» = major clinical significance).

Risk-benefit should be considered when the following medical problems exist
Biliary obstruction or
Renal dysfunction    (may cause an accumulation of molybdenum, since molybdenum is normally eliminated in bile and urine; a reduction in molybdenum dosage may be necessary {01} {10})

Copper deficiency    (condition may be exacerbated due to the mobilization of tissue copper and increased urinary excretion of copper by thiomolybdate {01} {06} {09} {14})

Patient monitoring
The following may be especially important in patient monitoring (other tests may be warranted in some patients, depending on condition; » = major clinical significance):

Copper    (serum copper concentrations may be decreased by thiomolybdate {14}; monitoring of copper every six months {12} may be required with long-term use of molybdenum {01})

Molybdenum, blood or urinary{01}{05}    (monitoring every six months by atomic absorption spectrophotometric method may be recommended by some clinicians to determine molybdenum status if deficiency or toxicity of molybdenum is suspected {03} {13})

Purine and sulfur metabolic profiles    (monitoring every six months may be recommended by some clinicians if deficiency or toxicity of molybdenum is suspected {01} {03} {13})

Side/Adverse Effects
No side effects have been reported with molybdenum with recommended dosages. {01}

For information on the management of overdose or unintentional ingestion, contact a Poison Control Center (see Poison Control Center Listing ).

Clinical effects of overdose
The following effects have been selected on the basis of their potential clinical significance (possible signs and symptoms in parentheses where appropriate)—not necessarily inclusive:
Hyperuricemia (joint pain; side, lower back, or stomach pain; swelling of feet or lower legs)—rarely has been reported from consumption of foods grown in molybdeniferous soil{04}

Patient Consultation
As an aid to patient consultation, refer to Advice for the Patient, Molybdenum Supplements (Systemic).

In providing consultation, consider emphasizing the following selected information (» = major clinical significance):

Description of use
Description should include function in the body, signs of deficiency

Importance of diet
Importance of proper nutrition; supplement may be needed because of inadequate dietary intake

Food sources of molybdenum

Recommended daily intake for molybdenum

Proper use of this dietary supplement

» Proper dosing
Missed dose: No cause for concern because of length of time necessary for depletion; remembering to take as directed

» Proper storage

Precautions while taking this dietary supplement
Importance of taking copper supplement

General Dosing Information
Because of the infrequency of molybdenum deficiency alone, combinations of several vitamins and/or minerals are commonly administered. In the oral form, molybdenum is available only as a vitamin/mineral combination.

For parenteral dosage forms only
In most cases, parenteral administration is indicated only when oral administration is not acceptable (for example, in nausea, vomiting, preoperative and postoperative conditions) or possible (for example, in malabsorption syndromes or following gastric resection).

Recommended dietary intakes for molybdenum are defined differently worldwide.

For U.S.:
The Recommended Dietary Allowances (RDAs) for vitamins and minerals are determined by the Food and Nutrition Board of the National Research Council and are intended to provide adequate nutrition in most healthy persons under usual environmental stresses. In addition, a different designation may be used by the FDA for food and dietary supplement labeling purposes, as with Daily Value (DV). DVs replace the previous labeling terminology United States Recommended Daily Allowances (USRDAs). {16}

For Canada:
Recommended Nutrient Intakes (RNIs) for vitamins, minerals, and protein are determined by Health and Welfare in Canada and provide recommended amounts of a specific nutrient while minimizing the risk of chronic diseases. {17}

There is no RDA or RNI established for molybdenum. The following daily intakes are considered adequate for all individuals {04}:

Infants and children—
Birth to 3 years of age: 15 to 50 mcg.

4 to 6 years of age: 30 to 75 mcg.

7 to 10 years of age: 50 to 150 mcg.

Adolescents and adults—
75 to 250 mcg.

The amount of molybdenum in foods varies, depending on the environment in which the food is grown. {04} Legumes, grain products, leafy vegetables, and low-fat milk are good sources of molybdenum. {08} {09}

Parenteral Dosage Forms


Usual adult and adolescent dose
Deficiency (treatment)
Intravenous, 163 mcg (0.163 mg) elemental molybdenum a day, added to total parenteral nutrition (TPN). {01}

Deficiency (prophylaxis)
Intravenous, 20 to 120 mcg (0.02 to 0.12 mg) elemental molybdenum a day, added to total parenteral nutrition (TPN). {01}

Strength(s) usually available

46 mcg (0.046 mg) (25 mcg elemental molybdenum) per mL (Rx) [Molypen][Generic]

Not commercially available.

Packaging and storage:
Store below 40 °C (104 °F), preferably between 15 and 30 °C (59 and 86 °F), unless otherwise specified by manufacturer.

Preparation of dosage form:
Ammonium molybdate is physically compatible with amino acid solutions, dextrose solutions, electrolytes, and other trace elements. {01}

Revised: 04/25/1995
Interim revision:

  1. Molypen product information (LyphoMed—U.S.) Rev 6/87.
  1. Ammonium molybdate product information (American Regent–U.S.) Rec 6/27/91, Rev 9/88.
  1. Nichoalds G. Molybdenum in Clinical guide to parenteral micronutrition. First Edition. Melrose Park, IL: Educational Publications, Inc, 1984: 165–72.
  1. National Research Council. Recommended dietary allowances. 10th ed. Washington, DC: National Academy Press, 1989: 243–6.
  1. Abumrad N, Schneider A, Steel D, Rogers L. Amino acid intolerance during prolonged total parenteral nutrition reversed by molybdate therapy. Am J Clin Nutr 1981; 34: 2551–9.
  1. Deosthale Y, Gopalan C. The effect of molybdenum levels in sorghum (Sorghum Vulgare Pers.) on uric acid and copper excretion in man. Br J Nutr 1974; 31: 351.
  1. Fleeger CA, editor. USAN 1995. USAN and the USP dictionary of drug names. Rockville, MD: The United States Pharmacopeial Convention, Inc., 1994: 46.
  1. Pennington J, Jones J. Molybdenum, nickel, cobalt, vanadium, and strontrum in total diets. J Am Diet Assoc 1987; 87: 1644–50.
  1. Rajagopalan K. Molybdenum: an essential trace element in human nutrition. Ann Rev Nutr 1988; 8: 401-27.
  1. Panelist comment, 1991.
  1. Panelist comments, 1991.
  1. Panelist comments, 1991.
  1. Panelist comments, 1991.
  1. Panelist comment, 1991.
  1. Consensus from Nutrition and Electrolytes Panel meeting, 1995.
  1. Food and Drug Administration. Focus on food labeling. FDA Consumer. May, 1993.
  1. Health and Welfare Canada. Nutrition recommendations, the report of the scientific committee. Ottawa, Canada: Canadian Government Publishing Centre, 1990: 11–2.