Content and stability of B complex vitamins in commercial cosmetic products.

BACKGROUND: Individual B vitamins have many favorable effects on the skin and are common cosmetic ingredients. However, their formulation is demanding due to stability issues, which consequently affect the products' quality. AIMS: We aimed to determine the quality (labeling accuracy, content determination, and content-related quality control) and stability under long-term and accelerated storage conditions of a representative sample of commercial cosmetics containing the most common B vitamins - nicotinamide, dexpanthenol, pyridoxine, and cyanocobalamin. METHODS: Cyanocobalamin was determined by a previously published stability-indicating HPLC- diode array detector (DAD) method for the simultaneous determination of all hydrophilic vitamins. This method was additionally simplified and adjusted for the time-effective analysis of nicotinamide, dexpanthenol, and pyridoxine. Both methods were properly validated. RESULTS: All labeled B vitamins were present in the 36 tested products, mostly in contents, reported effective on the skin. Thus, a straightforward correlation between vitamin contents and product prices were not observed. The content-related quality control of eight products, which quantitively specify their content, revealed significantly lower nicotinamide contents (47% and 57%) in two products and appropriate or higher nicotinamide (102%-112%) and dexpanthenol (100%-104%) contents than declared in the remaining products. The 6-month long-term and accelerated stability studies demonstrated the products' physical stability, but also revealed dexpanthenol, pyridoxine, and cyanocobalamin degradation, while nicotinamide was mostly stable in the tested products. CONCLUSIONS: The obtained results provide an inside into the quality of commercial vitamin B cosmetics and highlight the importance of stability testing in the formulation of quality, efficient, and safe cosmetics.

Evaluation of the stability of hydrocortisone sodium succinate in solutions for parenteral use by a validated HPLC-UV method.

This study aimed to determine the in-use stability (t95%) of hydrocortisone sodium succinate (HSS) infusion solutions and provide evidence-based guidelines on their usability.HSS infusion solutions were prepared and stored as recommended by the manufacturer and under common conditions in our hospital. The effects of HSS concentration (1 and 4 mg/mL), solvent (isotonic saline and glucose), temperature (ambient and 30°C), and light on its stability were evaluated using a validated stability-indicating HPLC-UV method.HSS degradation followed first-order kinetics. No significant difference in its stability was observed between the two evaluated concentrations, solvents and light exposure (t95% between 25 and 30 h). Elevated temperature (30°C) affected HSS stability and significantly reduced the t95% (4.6-6.3 h).HSS infusion solutions are physically and chemically stable (˂5% degradation) for at least 6 h if stored below 30°C. The in-use stability may be extended up to 24 h if stored below 24°C.

Vitamin B12 in Foods, Food Supplements, and Medicines-A Review of Its Role and Properties with a Focus on Its Stability.

Vitamin B12, also known as the anti-pernicious anemia factor, is an essential micronutrient totally dependent on dietary sources that is commonly integrated with food supplements. Four vitamin B12 forms-cyanocobalamin, hydroxocobalamin, 5'-deoxyadenosylcobalamin, and methylcobalamin-are currently used for supplementation and, here, we provide an overview of their biochemical role, bioavailability, and efficacy in different dosage forms. Since the effective quantity of vitamin B12 depends on the stability of the different forms, we further provide a review of their main reactivity and stability under exposure to various environmental factors (e.g., temperature, pH, light) and the presence of some typical interacting compounds (oxidants, reductants, and other water-soluble vitamins). Further, we explore how the manufacturing process and storage affect B12 stability in foods, food supplements, and medicines and provide a summary of the data published to date on the content-related quality of vitamin B12 products on the market. We also provide an overview of the approaches toward their stabilization, including minimization of the destabilizing factors, addition of proper stabilizers, or application of some (innovative) technological processes that could be implemented and contribute to the production of high-quality vitamin B12 products.

Comprehensive Stability Study of Vitamin D3 in Aqueous Solutions and Liquid Commercial Products.

Vitamin D3 has numerous beneficial effects, such as musculoskeletal, immunomodulatory, and neuroprotective. However, its instability is the main obstacle to formulating quality products. Despite increased attention and growing use, data on vitamin D3 stability is scarce because data from individual studies is inconclusive and mostly qualitative. Therefore, we have systematically investigated the influence of various factors (temperature, light, oxygen, pH, concentration, and metal ions) on its stability in aqueous media using a stability-indicating HPLC-UV method. First-order kinetics fitted its degradation under all tested conditions except light and oxygen. In both cases, the established models in chemical kinetics were inappropriate and upgraded with the Weibull model. Metal ions and acidic conditions had the main destabilizing effect on vitamin D3 in aqueous media, but these solutions were successfully stabilized after the addition of ethylenediaminetetraacetic acid (EDTA), ascorbic acid, and citric acid, individually and in combination. EDTA showed the most significant stabilizing effect. Synergism among antioxidants was not observed. Our findings on vitamin D3 instability in aqueous media also correlated with its instability in commercial products. Vitamin D3 aqueous products require proper stabilization, thereby signifying the importance and contribution of the obtained results to the formulation of stable and quality products.

Stability of Reduced and Oxidized Coenzyme Q10 in Finished Products.

The efficiency of coenzyme Q10 (CoQ10) supplements is closely associated with its content and stability in finished products. This study aimed to provide evidence-based information on the quality and stability of CoQ10 in dietary supplements and medicines. Therefore, ubiquinol, ubiquinone, and total CoQ10 contents were determined by a validated HPLC-UV method in 11 commercial products with defined or undefined CoQ10 form. Both forms were detected in almost all tested products, resulting in a total of CoQ10 content between 82% and 166% of the declared. Ubiquinol, ubiquinone, and total CoQ10 stability in these products were evaluated within three months of accelerated stability testing. Ubiquinol, which is recognized as the less stable form, was properly stabilized. Contrarily, ubiquinone degradation and/or reduction were observed during storage in almost all tested products. These reactions were also detected at ambient temperature within the products' shelf-lives and confirmed in ubiquinone standard solutions. Ubiquinol, generated by ubiquinone reduction with vitamin C during soft-shell capsules' storage, may lead to higher bioavailability and health outcomes. However, such conversion and inappropriate content in products, which specify ubiquinone, are unacceptable in terms of regulation. Therefore, proper CoQ10 stabilization through final formulations regardless of the used CoQ10 form is needed.

A comprehensive approach for the simultaneous analysis of all main water-soluble vitamins in multivitamin preparations by a stability-indicating HPLC-DAD method.

A stability-indicating HPLC-DAD method for simultaneous determination of all nine main water-soluble vitamins, in addition to two commonly used vitamers, was developed and fully validated in analytical ranges, adjusted to their recommended dietary allowance values. An XSelect CSH C18 column with gradient elution using phosphate buffer and methanol was used for their optimal separation. The results from forced degradation studies along with peak purity tests and response ratios at dual wavelengths for the individual vitamins in all tested samples confirmed the method's stability-indicative nature. The complete developed methodology, including a single sample preparation for the vitamins simultaneous analysis, was applied to their assay in 13 commercial multivitamin preparations, revealing mostly higher amounts than the label claims. The developed method is applicable for stability testing, multivitamin products shelf-life determination as well as routine assay analysis of all water-soluble vitamins in their most common forms, including the analytically most demanding flavin mononucleotide.

Quality control of retinoids in commercial cosmetic products.

BACKGROUND: Retinoids are widely used in different cosmetic products because of general improvement of skin appearance. However, retinoid concentration in cosmetics is restricted, and one particular form-retinoic acid, is banned in cosmetics due to safety reasons. AIMS: Within this study, we aimed to examine the quality of a considerable number of commercial retinoid cosmetic products in terms of their content and labeling, including also screening for the presence of retinoic acid. METHODS: An appropriate analytical methodology, based on HPLC-UV for the simultaneous determination of common retinoids, along with a screening method for retinoic acid, was developed and validated. Structural identity confirmation of the newer retinoid-hydroxypinacolone retinoate, was performed by LC-MS. RESULTS: Retinol and retinyl palmitate were most often found, in concentrations mostly below 0.3%, and up to 1.3% retinol equivalents. Determined contents deviated significantly from the quantitatively declared ones in seven products (0%-130%). In more than half of the tested products, inconsistencies between the contained and labeled retinoid were noticed. These products, as well as 14 additional anti-age cosmetics, were screened for retinoic acid, which was detected in two products. CONCLUSIONS: The obtained results from retinoids assay in commercial cosmetic products confirmed that the proposed method is appropriate for their routine analysis. The presence of retinoic acid in two products and determined retinoid contents above the Scientific Committee on Consumer Safety recommendations in 20% of the tested cosmetics reveal the need for their more strict regulation and quality control to ensure their efficacy and safety.

Retinoid stability and degradation kinetics in commercial cosmetic products.

BACKGROUND: Retinoids as dermatological agents are effective against acne, psoriasis, skin aging, and other skin conditions. However, their susceptibility to degradation is a limiting factor for their widespread use. OBJECTIVES: Within this study, we aimed to provide comprehensive and evidence-based information on retinoid stability and degradation kinetics in commercial cosmetics, focusing on different factors affecting their stability. METHODS: A validated HPLC-UV methodology was utilized for determination of the most common retinoids in cosmetics (retinol, retinyl palmitate, ß-carotene) and a newer promising retinoid (hydroxypinacolone retinoate). The stability of 16 retinoid derivatives in 12 commercial cosmetics was evaluated within 6 months of long-term and accelerated stability testing in addition to a one-week photostability study. Retinoid degradation in the tested formulations followed first-order kinetics, which was further applied to shelf-life prediction. RESULTS: Long-term and accelerated stability testing revealed retinoid instabilities in almost all products, resulting in a 0%-80% decline after 6 months at 25°C and a 40%-100% decline at 40°C, which were kinetically evaluated. Light degradation was more pronounced than temperature-induced degradation. Among the studied retinoids, the stability of the newer hydroxypinacolone retinoate was the most prominent. This study also identifies correlations between retinoid concentrations, price, formulation, and their stability in cosmetics. CONCLUSIONS: Retinoid instabilities were formulation-dependent and associated with lower contents than declared in some cosmetics. Retinoid chemical stability and physical stability in topical formulations need to be evaluated by real-time stability studies, instead of the more frequently used accelerated stability studies.

Quantification of reduced and oxidized coenzyme Q10 in supplements and medicines by HPLC-UV.

Coenzyme Q10 (CoQ10) supplements are widely used because of their antioxidant and anti-inflammatory effects, especially in the management of cardiovascular diseases. The latest pharmaceutical approach to increase CoQ10 bioavailability and efficiency is the formulation of its reduced form. Regardless of the growing number and usage of CoQ10 preparations, their analytics and quality control is inadequate, neglecting interconversion between the two CoQ10 forms. Therefore, this study proposes a HPLC-UV method for the simultaneous quantification of both reduced and oxidized coenzyme Q10, as well as total CoQ10, as a sum of its individual forms. The suitability of the developed method was confirmed by two additional approaches for total CoQ10 determination - its total reduction and oxidation, differing from the proposed procedure only in the final stage of sample preparation. The results for total CoQ10 content were consistent between the three procedures and also with the official USP method for total CoQ10 determination. The proposed method was applied to 13 dietary supplements and medicines in the form of soft- and hard-shell capsules, revealing the co-existence of both CoQ10 forms in 85% of the tested preparations. CoQ10 forms that were undeclared accounted for up to 75% of the CoQ10 content, which is overlooked by current official methods that evaluate only the total CoQ10 content. This validated HPLC-UV method for the unequivocal quantification of reduced and oxidized CoQ10 is therefore appropriate for the routine analysis of CoQ10 preparations in quality control laboratories, as well as for stability studies, and is suggested to be adopted as an official method.

Fast and Simple LC-MS/MS Method for Rifampicin Quantification in Human Plasma.

A simple, fast, and cost-effective LC-MS/MS method for quantification of rifampicin in human plasma was developed and fully validated. The plasma samples containing rifampicin and isotopically labelled internal standard rifampicin D8, were cleaned up using a Captiva ND Lipids filtration plate. Chromatographic separation was achieved on an 1290 Infinity liquid chromatograph coupled to 6460 Triple Quadrupole operated in positive mode on a core-shell Kinetex C18 column (50 × 2.1 mm, 2.6 µm) by gradient elution using 0.1% formic acid in water and acetonitrile as a mobile phase. The proposed method is the fastest method published by now, both in terms of sample preparation (approximately one minute per sample) and chromatographic analysis (total run time 2.4 min). Another key benefit is the outstanding sensitivity and wide analytical range (5-40000 µg/L) with good linearity, accuracy, and precision. The method showed almost complete recovery (92%) and absence of any significant matrix effect as demonstrated by uniform responses from QC samples prepared in blood plasma from 6 volunteers (RSD <5%). The proposed method was successfully applied to rifampicin quantification in 340 patients' plasma samples, thus demonstrating its suitability for both therapeutic drug monitoring and pharmacokinetic analysis.

Novel HPLC-UV Method for Simultaneous Determination of Fat-soluble Vitamins and Coenzyme Q10 in Medicines and Supplements.

A precise, accurate and rapid HPLC-UV method for simultaneous determination of fat-soluble vitamins (vitamin D3, E-acetate, K1, ß-carotene, A-palmitate) and coenzyme Q10 was developed and validated according to ICH guidelines. Optimal chromatographic separation of the analytes in minimal analysis time (8 min) was achieved on a Luna C18 150 × 4.6 mm column using a mixture of acetonitrile, tetrahydrofuran and water (50:45:5, v/v/v). The described reversed phase HPLC method is the first published for quantification of these five fat-soluble vitamins and coenzyme Q10 within a single chromatographic run. The method was further applied for quantification of the analytes in selected liquid and solid dosage forms, registered as nutritional supplements and prescription medicines, which confirmed its suitability for routine analysis.

Development of medicated foams that combine incompatible hydrophilic and lipophilic drugs for psoriasis treatment.

The focus was on the development of medicated foam for incorporation of two incompatible active agents for psoriasis treatment; i.e., lipophilic cholecalciferol, and hydrophilic salicylic acid. Emphasis was given to formulation of a propellant-free foam, with sufficient foaming properties, physical and chemical stability, and low irritancy potential to maintain relevance for later translation into clinical practice. Various excipients and concentrations were examined to achieve suitable foam stability parameters, viscoelasticity, and bubble-size, which relate to foamability and spreadability. The major positive impact on these properties was through a combination of surfactants, and by inclusion of a viscosity-modifying polymer. Incorporation of the incompatible drugs was then examined, noting the instability of cholecalciferol in an acidic environment, with the design aim to separate the drug distributions among the different foam phases. Cholecalciferol was stabilized in the emulsion-based foam, with at least a 30-fold lower degradation rate constant compared to its aqueous solution. The composition of the emulsion-based foam itself protected cholecalciferol from degradation, as well as the addition of the radical-scavenging antioxidant tocopheryl acetate to the oil phase. With the patient in mind, the irritancy potential was also examined, which was below the set limit that defines a non-irritant dermal product.