Microcirculatory response of skin to benzoic acid and methyl nicotinate in patients with diabetes

Filling data gap for nicotinic acid, nicotinate esters and nicotinamide for the determination of permitted daily exposure by a category approach

This study aimed to obtain necessary toxicological data using experimental and computational methods for the calculation of a common permitted daily exposure (PDE) which can be relevant for nicotinic acid and its esters and nicotinamide according to European Medicines Agency Guideline on setting health-based exposure limits. PDE calculation is mainly based on critical toxicological endpoints. During this procedure, critical toxicological endpoints data of an active pharmaceutical ingredient (API) may not be able to find satisfactorily. Hence, using toxicological data for another API that has a similar chemical structure can be a useful way. In this study, toxicological endpoints of nicotinic acid and its esters and nicotinamide were evaluated. Then, the data gaps in the toxicological endpoints were filledusing the read-across approach. Based on the current existing data, nicotinic acid and its esters and also nicotinamide are not genotoxic and do not have skin sensitization potential. These compounds do not present a concern for carcinogenicity and developmental/reproductive toxicity. Based on these critical endpoints and available experimental data, the final PDE of 10 mg/day was calculated for all category members. Our study showed the utility of the read-across for PDE calculation of APIs with experimental toxicological data gap.

Sterol-standardized phytopharmaceutical from ground cherry: Corticoid-like properties on human keratinocytes and fibroblasts and its effects in a randomized double-blind placebo-controlled clinical trial

BACKGROUND

Topical corticosteroids have been the most commonly prescribed drugs to treat skin inflammation, but their uses can lead to several adverse effects. Nowadays, new pharmacological strategies have been evaluated to improve dermatologic efficacy and reduce adverse effects, including natural products.

OBJECTIVES

The aim of this study was to evaluate and compare the effects of a plant sterol standardized supercritical CO₂ phytopharmaceutical of Physalis angulata L. with hydrocortisone on the immune and inflammatory mediators, and skin repair components production. Moreover, we studied effects of both products on the skin microcirculation and temperature in a double-blind placebo-controlled clinical trial.

METHODS

Both products were evaluated on the immune (IL-6, IL-10, INF-γ, TNF-α, and IL-1α), inflammatory (COX-2, LOX, PLA₂ , PGE₂ , LTB₄ , histamine, and NF-κB), and repair components (TGF-β, GM-CSF, collagen, and GAG) production on human keratinocytes and fibroblast in non-stimulated and LPS-stimulated conditions. Indeed, in a randomized double-blind placebo-controlled clinical trial, we evaluated the effects of the both creams on the skin microcirculation and temperature using laser Doppler and infrared thermometer, respectively.

RESULTS

Physalis angulata acted on the skin, modulating immune status and inflammatory response producing corticoid-like effects, but different of hydrocortisone, increased skin repair factors. The effects of phytopharmaceutical cream in the clinical trial promoted a better reduction in skin microcirculation and temperature than hydrocortisone.

CONCLUSIONS

Taken together, the results indicate that sterol standardized CO₂ supercritical preparation of P angulata is a new and innovative phytopharmaceutical with multiple pharmacological effects potentially useful as human skin protective product, particularly against cutaneous inflammatory disorders.

Establishing a minimal erythema concentration of methyl nicotinate for optimum evaluation of anti-inflammatories

Topical administration of chemicals such as methyl nicotinate that induce erythema have been employed to measure the effectiveness of formulations containing anti-inflammatory agents. Prior studies have utilized a single concentration of methyl nicotinate, between 36.5 and 100 mM, for all test subjects in evaluations of topical formulations. However, individuals have different thresholds of response to methyl nicotinate; thus, a single concentration may not be appropriate for all individuals and could result in the apparent lack of anti-inflammatory activity of the formulation being evaluated. In the current study, we evaluated the use of a minimal erythema concentration (MEC) of methyl nicotinate, defined as the lowest concentration that produces a complete and even erythema at the test site, compared with a 36.5-mM concentration of methyl nicotinate. Hydroalcoholic gels containing the nonsteroidal anti-inflammatory drug ibuprofen were compared with placebo. Diffuse reflectance spectroscopy was employed to measure differences in cutaneous inflammatory response between the control (placebo)-treated group and the ibuprofen-treated group. When chemical erythema was induced using an MEC of methyl nicotinate, greater reductions in erythema were seen in ibuprofen-treated sites compared with sites treated with a 36.5-mM concentration of methyl nicotinate. In conclusion, for an accurate assessment method of erythema induced by methyl nicotinate, consideration should be given to determining the extent of response of an erythema-producing agent on an individual basis. An MEC of methyl nicotinate should be determined and employed for each individual to obtain more consistent and reliable efficacy results of anti-inflammatory activity.

Topical methyl nicotinate-induced skin vasodilation in diabetic neuropathy

OBJECTIVE

To evaluate the vasodilation induced by topical application of methyl nicotinate (MN) and to compare it with the vasodilatory response to acetylcholine (ACh) and sodium nitroprusside (SNP) in healthy subjects and diabetic neuropathic patients.

RESEARCH DESIGN AND METHODS

Ten diabetic patients with peripheral neuropathy (DN) and 10 age- and sex-matched healthy control subjects (C) were enrolled. The vasodilatory response to topical application of 1% MN and a placebo emulsion at the forearm and dorsum of the foot skin at 5, 15, 30, 60 and 120 min was measured using Laser Doppler Perfusion Imaging. The vasodilatory response to iontophoresis of 1% ACh and 1% SNP solutions was also evaluated.

RESULTS

The maximal vasodilatory response to ACh, SNP and MN was similar at the forearm and foot level in the diabetic patients. In the control group, the responses to MN, ACh and SNP were similar on the forearm but in the foot, the MN vasodilatory response was higher when compared to the ACh and SNP responses. MN-related vasodilation was present 5 min after the application, reached its peak at 15-30 min and declined to pre-application levels 120 min afterward.

CONCLUSIONS

Topical application of MN at the forearm and foot levels of diabetic neuropathic patients results in skin vasodilation that is comparable to the maximal vasodilation that can be induced by iontophoresis of ACh or SNP and lasts for less than 2 h. Further studies will be required to explore the potential of MN to increase blood flow and to prevent diabetic foot problems in clinical practice.