A Phase 4 interventional study of N-acetylcysteine, intralipid, heparin in Insulin Resistance Syndrome X and Pancreatic Beta Cell Function, sponsored by University Health Network, Toronto. Completed at 1 site in Canada. Open to male participants aged 35 Years to 65 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2008-06-05.
Sponsored by University Health Network, Toronto · Phase 4, Interventional, and Diagnostic
A prolonged elevation of plasma free fatty acids (FFA) impairs glucose stimulated insulin secretion. The concept of fatty acid impairment of glucose stimulated insulin secretion (lipotoxicity) has now been well accepted. Increased free fatty acid flux from adipose tissue to non-adipose tissue, resulting from abnormalities of fat metabolism, participates in and amplifies many of the metabolic derangements that are characteristic of insulin resistance syndrome and type 2 diabetes.
Lipotoxicity is also likely to play an important role in the progression from normal glucose tolerance to fasting hyperglycemia and conversion to frank type 2 diabetes in insulin resistant individuals. This area of research is now focused on determining the mechanisms whereby FFAs impair b-cell function. There is some evidence to suggest that lipotoxicity could be mediated through induction of reactive oxygen species (ROS). N-acetylcysteine (NAC) is a known potent antioxidant and has been used experimentally in a number of medical conditions in humans for its protective antioxidant effects. The investigators now plan to administer NAC orally to humans for 48 hours to examine the effects of antioxidant therapy in ameliorating the deleterious effects of FFAs on pancreatic beta cell function. NAC is currently approved for the treatment of acetaminophen overdose and is also used as a mucolytic agent. The investigators are now using NAC as an antioxidant to determine whether it protects the pancreatic beta cell against the toxic effects of FFAs, as outlined in the detailed study protocol. This is a proof-of-principle study and is not designed to develop n-acetylcysteine for therapeutic use.
Free fatty acids will be elevated approximately 2-fold for 48 hours by intravenous infusion of Intralipid and heparin. 15 abdominally obese insulin resistant, but otherwise healthy, non-diabetic men will be studied on three occasions each, in random order, 4 weeks apart. We have chosen to study abdominally obese, insulin resistant individuals rather than lean healthy controls because we have previously shown that these individuals are more susceptible to lipotoxicity and we are therefore more likely to see differences between the interventions if differences indeed exist. Informed written consent will be obtained from all participants in accordance with the guidelines of the Human Subjects Review Committee of the University Health Network.
Subjects will be hospitalized in the Metabolic Investigation Unit (MIU) of the Toronto General Hospital for each of their three studies, which will be performed in random order 4 to 6 weeks apart. On one occasion a saline control study will be performed, on a second occasion Intralipid (20% solution @ 40ml/hr) and heparin (250u/hr) will be infused for 48 hours as previously described and on a third occasion NAC will be administered orally concurrently with the Intralipid and heparin. The dose of NAC will be the same as that recommended for acetaminophen overdose. An initial loading dose of 140mg/kg NAC followed by a maintenance dose of 70mg/kg every 4 hours during the 48 hour infusion of Intralipid and heparin. On day three, testing of glucose-stimulated insulin secretion (GSIS) will occur as outlined below. Subjects will be provided with an isocaloric diet consisting of 50% calories derived from carbohydrates, 30% fat and 20% protein during the 48 hour infusions and will fast from midnight for the testing of pancreatic beta cell function on day three.
1,959 studies on the registry are indexed under Insulin Resistance; 305 are open to participants now.
This study's planned enrollment of 15 is below the median of 40 across 1,535 interventional studies indexed under Insulin Resistance.
Browse Insulin Resistance studies →University Health Network, Toronto is the lead sponsor of 1,411 studies on the registry; 292 are open to participants now.
Of its 17 completed or terminated interventional studies of FDA-regulated products, 3 (18%) have results posted.
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The following criteria will be used for the selection of insulin resistant non-diabetic men aged 35-65 years:
Exclusion Criteria:
One visit subject will receive N-acetylcysteine plus intralipid and heparin, another visit n-acetylcyksteine plus saline, another visit intralipid and heparin and another visit saline alone
To determine whether the FFA-induced impairment of pancreatic b-cell function can be ameliorated or prevented by administration of the antioxidant, NAC
Time frame: 2 years
Assessment of insulin sensitivity
Time frame: 2 years
To determine whether administration of NAC, an antioxidant, prevents FFA-mediated impairment of GSIS in healthy humans.
Time frame: 2 years
assessment of glucose stimulated insulin secretion
Time frame: 2 years
This study is completed, as verified in Jun 2007. You cannot join it, but the record below documents what was studied.
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University Health Network, Toronto