proposed amendment to the food and drug regulations notice of intent project no. 1656 schedule f 4 pages available in english and french the purpose of this notice of intent noi is to provide an opportunity for comment on the proposal to amend the current listings in part i of schedule f to the food and drug regulations for three medicinal ingredients to retain prescription status for specific strengths uses routes of administration or dosages while providing exemptions that would allow non-prescription status. since the coming into force of the natural health products regulations in 2004 all naturally sourced substances meeting the definition of a natural health product are governed by these regulations. however products containing substances listed in schedule f to the food and drug regulations are explicitly excluded from the natural health products regulations. health canada has undertaken a review of the naturally sourced medicinal ingredients listed in schedule f. as part of this undertaking the departments drug schedule status committee the committee has reviewed science assessments for 11 naturally sourced medicinal ingredients and has recommended that these medicinal ingredients could be regulated in whole or in part as non-prescription natural health products under the natural health products regulations. three of these eleven medicinal ingredients are presented in this project. this proposed amendment would allow manufacturers to apply for market authorization for products containing the proposed exempted strengths uses routes of administration or dosages of the following three medicinal ingredients as natural health products pursuant to the natural health products regulations. description of the medicinal ingredients dimethyl sulfoxide the current listing for dimethyl sulfoxide also referred to as dmso would be revised to retain prescription status for human use when dimethyl sulfoxide is sold for the treatment of interstitial cystitis or scleroderma and for all veterinary uses. all other human uses for dimethyl sulfoxide at any strength and in any dosage form would be exempt from prescription status. dimethyl sulfoxide is found in many natural sources such as broad beans alfalfa and garlic. drugs containing dimethyl sulfoxide for human use are available in canada with a prescription for treatment of interstitial cystitis a urinary bladder condition and scleroderma abnormal growth of connective tissue that supports the skin . several products are currently available as prescription drugs for veterinary use to treat conditions such as ear inflammation in dogs. these products would retain prescription status. levocarnitine the current listing for levocarnitine also called l-carnitine would be revised to retain prescription status for levocarnitine and its salts and derivatives when sold for the treatment of primary or secondary levocarnitine deficiencies. levocarnitine and its salts and derivatives for any other uses at any strength dosage form or route of administration would be exempt from prescription status. levocarnitine occurs naturally in animal products and in small amounts in most plants. overall levocarnitine functions in the body mainly in optimal fat utilization for energy production. absorption of levocarnitine is high from dietary sources but if dietary intake is low then the body can maintain a balanced level by synthesizing or reducing elimination of levocarnitine. in most people sufficient quantities of levocarnitine are obtained from the diet or synthesized in order to meet human requirements. primary levocarnitine deficiency is a genetically inherited condition related to the processing of levocarnitine in the body and can lead to muscle weakness and death from heart failure. secondary levocarnitine deficiency syndromes are numerous and include genetic defects of metabolism. treatment of these conditions with levocarnitine requires the supervision of a practitioner and routine laboratory monitoring. l-tryptophan the current listing for l-tryptophan when sold as a single ingredient would be revised to provide prescription status for l-tryptophan when sold for human use in oral dosage form as a single ingredient or in combination with other ingredients at a concentration of more than 220 mg l-tryptophan per dosage unit or per daily dose and when sold for human use or veterinary use as a single ingredient for any route of administration other than oral use. l-tryptophan is one of the essential amino acids that cannot be synthesized in the human body and must be provided in the diet. l-tryptophan acts in the body in the formation of the vitamin niacin and the neurotransmitter serotonin. l-tryptophan is available in canada as a prescription drug for use in combination with antidepressant drugs to enhance the activity of the antidepressant. l-tryptophan is also sold in combination with other amino acids in kidney dialysis and intravenous nutrition solutions without a prescription. the proposed amendment would not change the status of these products. schedule f is a list of medicinal ingredients the sale of which is controlled under sections c.01.041 to c.01.049 of the food and drug regulations. part i of schedule f lists ingredients that require a prescription for human use and for veterinary use. part ii of schedule f lists ingredients that require a prescription for human use but do not require a prescription for veterinary use if so labelled or if in a form unsuitable for human use.