Gary Robert Kelm

Reduction in the appearance of facial hyperpigmentation by topical N-acetyl glucosamine.

Glucosamine has been reported to inhibit melanin production in melanocyte culture. It thus has a potential to reduce hyperpigmentation via topical use. Due to stability limitations of glucosamine, we chose to clinically evaluate the stable derivative N‐acetyl glucosamine (NAG). Based on in vitro Franz cell testing, NAG is a good skin penetrant. In an 8‐week, double‐blind, placebo‐controlled, left‐right randomized, split‐face clinical test, topical 2% NAG reduced the appearance of facial hyperpigmentation. In a second clinical study involving the topical combination of 2% NAG with 4% niacinamide, an agent previously shown to be clinically active, the effect on hyperpigmentation was greater. Both of these agents are well tolerated by the skin. This high tolerance coupled with relative ease of formulation and stability in solution make NAG, especially in combination with niacinamide, a suitable cosmetic ingredient for use in skin care products dealing with issues of skin hyperpigmentation.

Jejunal or portal vein infusions of lipids increase hepatic vagal afferent activity.

Jejunal infusions of linoleic acid, corn oil, or caprylic acid significantly increased hepatic vagal afferent activity, whereas saline infusions were ineffective. The magnitude of response was greatest with either linoleic acid or corn oil. Hepatic portal infusions of linoleic acid, Liposyn II, or caprylic acid significantly increased hepatic vagal afferent activity, whereas 5% albumin/phosphate buffer vehicle was ineffective. The magnitude of response was greatest with either linoleic acid or Liposyn II. These data show that either jejunal or portal infusions of lipids increase activity of hepatic vagal afferents and could potentially serve as a complementary and/or alternative substrate to celiac vagal afferents in mediating the effects of jejunal infusions of lipids in suppressing food intake.

Truncal and hepatic vagotomy reduce suppression of feeding by jejunal lipid infusions.

Two experiments investigated mechanisms underlying the decrease in food intake produced by lipid infusions into the jejunum. In Experiment 1, male Sprague-Dawley rats with truncal abdominal vagotomy (TVx), selective hepatic-branch vagotomy (HVx), or sham vagotomy received repeated 7 h infusions of linoleic acid (LA), corn oil (CO), or saline through indwelling jejunal catheters. Cumulative food intake was measured at 1, 3, 6, and 23 h. LA and, to a lesser extent, CO suppressed food intake in excess of the caloric value of the load. This effect was eliminated by TVx, which significantly attenuated the suppression of intake produced by both lipids at 3 and 6 h and also at 23 h when LA was infused. HVx attenuated suppression at 23 h on tests with LA and at 3 and 6 h on CO tests. Experiment 2 showed that jejunal infusion of LA had no effect on multi-unit activity of afferent fibers in the left splanchnic nerve in anesthetized rats. Thus, these results provide further evidence that satiating effects of intestinal lipid infusions are mediated by the vagal fibers, some of which lie within the hepatic branch. However, because significant suppression of food intake remained after TVx, and because of the negative results of Experiment 2, these lipid infusions engage as yet unidentified mechanisms independent of the vagus.

Interspecies Scaling of Tebufelone Pharmacokinetic Data and Application to Preclinical Toxicology

AbstractPurpose. Retrospective application of allometric scaling techniques to tebufelone, a nonsteroidal antiinflammatory agent, in order to better understand the systemic exposure relationships between the doses administered to the species used in toxicology studies and the doses given to human subjects and patients in clinical studies. Methods. Non-compartmental estimates of tebufelones total body volume of distribution during the terminal phase (Vz) and clearance (CL) obtained from intravenous dosing to rat, monkey, dog, and human were allometrically scaled to body weight, and body weight and brain weight, respectively. AUCs determined from single or multiple dose pharmacokinetic studies and from preclinical toxicology studies were plotted versus dose adjusted for bioavailability and divided by allometrically scaled clearance to produce an allometric relationship suggesting a non-linear increase in AUC with dose across the four species. Results. Segmental linear regression analysis of this relationship indicates a change point associated with an AUC of approximately 2,300 ng-hr/mL. Elevations in serum levels of various liver enzymes or associated signs of hepatic toxicity occur in some, but not all of the animals exposed for more than three weeks in repeat dosing studies at the actual dose that this represents. Conclusions. The analysis suggests that doses producing tebufelone plasma levels above a certain threshold AUC and duration of exposure to parent tebufelone are associated with increased risks of hepatic effects. Whether this is because metabolic shifts occur at these doses cannot be determined from these data.

Reduction in the appearance of facial hyperpigmentation by topical N-undecyl-10-enoyl-l-phenylalanine and its combination with niacinamide

Objectives  N‐undecyl‐10‐enoyl‐l‐phenylalanine (Sepiwhite®, N‐undecylenoyl phenylalanine), a reported alpha‐melanocyte‐stimulating hormone (MSH) receptor antagonist, has been observed to reduce melanin production in cultured melanocytes. In other testing, niacinamide has been found to inhibit melanosome transfer in cultured cells and to reduce the appearance of hyperpigmented spots in clinical studies. Since these two agents function by different mechanisms, we conducted two studies to determine if their combination is more effective than niacinamide alone in reducing facial hyperpigmentation.

The safety of the use of ethyl oleate in food is supported by metabolism data in rats and clinical safety data in humans.

The absorption, distribution, and excretion of radiolabeled ethyl oleate (EO) was studied in Sprague-Dawley rats after a single, peroral dose of 1.7 or 3.4 g/kg body weight and was compared with a radiolabeled triacylglycerol (TG) containing only oleic acid as the fatty acid (triolein). Both test materials were well absorbed with approximately 70-90% of the EO dose absorbed and approximately 90-100% of the TG dose absorbed. At sacrifice (72 h post-dose), tissue distribution of EO-derived radioactivity and TG-derived radioactivity was similar. The tissue with the highest concentration of radioactivity in both groups was mesenteric fat. The other organs and tissues had very low concentrations of test material-derived radioactivity. Both test materials were rapidly and extensively excreted as CO(2) with no remarkable differences between their excretion profiles. Approximately 40-70% of the administered dose for both groups was excreted as CO(2) within the first 12 h (consistent with beta-oxidation of fatty acids). Fecal elimination of EO appeared to be dose-dependent. At the dose of 1.7 g/kg, 7-8% of the administered dose was eliminated in the feces. At the dose of 3.4 g/kg, approximately 20% of the administered dose was excreted in the feces. Excretion of TG-derived radiolabel in the feces was approximately 2-4% for both doses. Overall, the results demonstrate that the absorption, distribution, and excretion of radiolabeled EO is similar to that of TG providing evidence that the oleic acid moiety of EO is utilized in the body as a normal dietary TG-derived fatty acid. To confirm the expected safety of EO in humans, a total of 235 subjects participated in a 12-week trial where two levels of ethyl oleate in a milk-based beverage were investigated: 8 g/day in a single serving (approximately 0.1 g/kg) and 16 g/day taken in two divided servings (approximately 0.2 g/kg). Adverse events (AEs) were recorded throughout the 12-week trial. In addition, a brief physical exam (including vital signs and body weight), ECGs, fasting serum chemistry profile, serum lipid profile, and urinalysis were performed at baseline and after study completion. Results showed the incidence of reported AEs was similar between the EO groups and the control groups. Analysis of comprehensive laboratory data revealed no EO exposure-related, clinically significant adverse changes in laboratory parameters. These studies demonstrated that EO has a highly favorable safety profile and is well tolerated in the diet.

Comparison of Tissue Concentrations After Intramuscular and Topical Administration of Ketoprofen

AbstractPurpose. To assess whether topical ketoprofen, which has been reported to provide analgesic effects in clinical studies, reaches predictable tissue concentrations high enough to account for the reported analgesia. Intramuscular ketoprofen was used as positive control. Methods. Muscle and subcutaneous tissue concentrations were assessed by microdialysis. Plasma and tissue concentrations after intramuscular injection were described using a three-compartment population pharmacokinetic model. The prediction performance of the model was assessed by superimposing tissue concentrations of 12 subjects that did not participate in the present study. Results. Most dialysate concentrations after topical dosing of ketoprofen (100 mg) were below the quantification limit of 0.47 ng/ml. Plasma concentrations increased slowly and reached an apparent plateau of 7-40 ng/ml at 10-12h. No decline was observed up to 16 h. Tissue concentrations after intramuscular injection (100 mg) were about 10 times higher than those after topical dosing. Tissue concentrations measured in the majority of the 12 subjects that did not participate in the present study were found within the range of two-thirds of the predicted concentrations. Conclusion. Predictable and cyclooxygenase-inhibiting concentrations of ketoprofen were achieved in subcutaneous and muscle tissue after intramuscular but not after topical dosing. Thus, the tissue concentrations of ketoprofen after topical administration can hardly explain the reported clinical efficacy of topical ketoprofen.

Celiac vagotomy reduces suppression of feeding by jejunal fatty acid infusions

We investigated the role of the celiac branch of the vagus nerve in suppression of food intake produced by jejunal fatty acids infusions. Following selective celiac vagotomy or sham surgery, adult, male Sprague–Dawley rats received 7 h infusions of linoleic acid or saline through indwelling jejunal catheters on four consecutive days. Although linoleic acid still produced significant suppression of intake in rats with celiac vagotomy, it was less effective in these animals than in controls. The temporal pattern of results suggested that celiac afferent fibers are involved in mediating both pre- and postabsorptive effects of infused fatty acids.

Determination of two mebeverine metabolites, mebeverine alcohol and desmethylmebeverine alcohol, in human plasma by a dual stable isotope-based gas chromatographic-mass spectrometric method

A dual stable isotope-based GC-MS method was developed for the simultaneous determination of two metabolites of mebeverine, mebeverine alcohol and desmethylmebeverine alcohol, in human plasma. Plasma samples were treated with beta-glucuronidase to cleave the glucuronide conjugates of both compounds prior to analysis. The treated plasma was prepared for analysis by solid-phase extraction using octadecylsilane cartridges. The isolated metabolites were derivatized and analyzed by GC-MS using selected-ion monitoring. Plots of peak-area ratio were linear with metabolite concentration from 2 to 200 ng/ml and the limit of detection for both metabolites was 0.5 ng/ml. The GC-MS methodology was applied to the analysis of plasma from human subjects following peroral administration of mebeverine. Pharmacokinetic parameters for both metabolites were determined and suggest that relative systemic mebeverine exposure may potentially be assessed using metabolite kinetics, if the latter subsequently are demonstrated to be linear with mebeverine dose.

Responses of hepatic and celiac vagal afferents to intraportal mercaptoacetate in rats fed a high-fat or low-fat diet.

&NA; Responses of either hepatic or celiac vagal afferents to intraportal hepatic vein administration of 2‐mercaptoacetate (MA) were examined in rats maintained on either a high‐fat or low‐fat diet. Afferent activity in both hepatic and celiac vagal afferents significantly increased after administration of MA, but the magnitude of these increases did not differ as a function of either diet. Responses of hepatic vagal afferents were highly variable across individual rats, whereas those of celiac vagal afferents were remarkably consistent across individual rats. These data suggest that MA‐induced enhanced feeding in rats given a fat‐enriched diet does not depend on a stronger hepatic and/or celiac vagal afferent response than that of rats given a low‐fat diet.