Objective As part of the NIH-sponsored Glucosamine/Chondroitin Sulfate Arthritis Intervention Trial (GAIT) our objective here was to examine 1) the pharmacokinetics (PK) of glucosamine (GlcN) and chondroitin sulfate (CS) when taken separately or in combination as a single dose in normal individuals (n=29) and 2) the PK of GlcN and CS when taken as a single dose after 3 months daily dosing with GlcN, CS or GlcN+CS, in patients with symptomatic knee pain (n=28). Methods The concentration of GlcN in the circulation was determined by established fluorophore-assisted carbohydrate electrophoresis (FACE) methods. The hydrodynamic size and disaccharide composition of CS chains in the circulation and dosage samples was determined by Superose 6 chromatography and FACE. Results We show that circulating levels of CS in human plasma are about 20ug/ml. Most significantly, the endogenous concentration and CS disaccharide composition were not detectably altered by ingestion of CS, when the CS was taken alone or in combination with GlcN. On the other hand, the Cmax (single dose study) and AUC values (multiple dose study) for ingested GlcN were significantly reduced by combination dosing with CS, relative to GlcN dosing alone. Conclusions We conclude that pain relief perceived following ingestion of CS probably does not depend on simultaneous or prior intake of GlcN. Further, such effects on joint pain, if present, probably do not result from ingested CS reaching the joint space but may result from changes in cellular activities in the gut lining or in the liver, where concentrations of ingested CS, or its breakdown products, could be substantially elevated following oral ingestion. Moreover, since combined dosing of GlcN with CS was found to reduce the plasma levels seen with GlcN dosing alone, any improved pain relief by combination dosing cannot be explained by higher circulating concentrations of GlcN.

Background— In animal studies and a pilot trial in patients with congestive heart failure, the thyroid hormone analog 3,5 diiodothyropropionic acid (DITPA) had beneficial hemodynamic effects. Methods and Results— This was a phase II multicenter, randomized, placebo-controlled, double-blind trial of New York Heart Association class II to IV congestive heart failure patients randomized (2:1) to DITPA or placebo and treated for 6 months. The study enrolled 86 patients (n=57 to DITPA, n=29 to placebo). The primary objective was to assess the effect of DITPA on a composite congestive heart failure end point that classifies patients as improved, worsened, or unchanged based on symptom changes and morbidity/mortality. DITPA was poorly tolerated, which obscured the interpretation of congestive heart failure-specific effects. Fatigue and gastrointestinal complaints, in particular, were more frequent in the DITPA group. DITPA increased cardiac index (by 18%) and decreased systemic vascular resistance (by 11%), serum cholesterol (−20%), low-density lipoprotein cholesterol (−30%), and body weight (−11 lb). Thyroid-stimulating hormone was suppressed in patients given DITPA, which reflects its thyromimetic effect; however, no symptoms or signs of potential hypothyroidism or thyrotoxicosis were seen. Conclusions— DITPA improved some hemodynamic and metabolic parameters, but there was no evidence for symptomatic benefit in congestive heart failure.

Recently detoxified men with alcohol dependence (n = 15) and healthy volunteers (n = 14) were administered oral and intravenous imipramine and desipramine. Alcoholics had significantly greater total body clearance of imipramine (0.93 vs. 0.48 L/hr/kg; P less than 0.05) and desipramine (1.00 vs. 0.62 L/hr/kg; P less than 0.05) than did control subjects. Intrinsic clearance of unbound imipramine was greater in the alcoholic group (19.80 vs. 6.56 L/hr/kg; P less than 0.05), as was the intrinsic clearance of unbound desipramine (14.52 vs. 9.05 L/hr/kg; P less than 0.05). The mean elimination half-life for imipramine was significantly decreased in alcoholics (8.7 vs. 19.9 hours after intravenous infusion and 10.9 vs. 19.6 hours after oral administration; P less than 0.05). The mean elimination half-life for desipramine was decreased in alcoholics after intravenous infusion (16.5 vs. 22.4 hours; P less than 0.05). Unbound fractions of drug in plasma were decreased in the alcoholic group for both imipramine and desipramine after both routes of administration. alpha 1-Acid glycoprotein levels were elevated in the alcoholic group whereas total protein and albumin levels did not differ between groups. These findings suggest that recently detoxified alcoholics may require higher doses of imipramine than do nonalcoholic subjects. Desipramine clearance was affected to a lesser degree than imipramine, suggesting that from a pharmacokinetic standpoint it may be the preferred drug for the treatment of alcoholics with depression. Periodic monitoring of plasma levels may be required for recently abstinent alcoholics treated with antidepressants.

This investigation of DITPA actions demonstrated its efficacy in reducing body weight and lowering total and low-density lipoprotein cholesterol levels. However, DITPA's adverse effects at doses used resulted in a high dropout rate and potentially dangerous skeletal actions were observed.