1,721,019 research outputs found
Whey protein/polysaccharide-stabilized emulsions: effect of polymer type and pH on release and topical delivery of salicylic acid
No full textEmulsions are widely used as topical formulations in the pharmaceutical and cosmetic industries. They are thermodynamically unstable and require emulsifiers for stabilization. Studies have indicated that emulsifiers could affect topical delivery of actives, and this study was therefore designed to investigate the effects of different polymers, applied as emulsifiers, as well as the effects of pH on the release and topical delivery of the active. O/w emulsions were prepared by the layer-by-layer technique, with whey protein forming the first layer around the oil droplets, while either chitosan or carrageenan was subsequently adsorbed to the protein at the interface. Additionally, the emulsions were prepared at three different pH values to introduce different charges to the polymers. The active ingredient, salicylic acid, was incorporated into the oil phase of the emulsions. Physical characterization of the resulting formulations, i.e., droplet size, zeta potential, stability, and turbidity in the water phase, was performed. Release studies were conducted, after which skin absorption studies were performed on the five most stable emulsions, by using Franz type diffusion cells and utilizing human, abdominal skin membranes. It was found that an increase in emulsion droplet charge could negatively affect the release of salicylic acid from these formulations. Contrary, positively charged emulsion droplets were found to enhance dermal and transdermal delivery of salicylic acid from emulsions. It was hypothesized that electrostatic complex formation between the emulsifier and salicylic acid could affect its release, whereas electrostatic interaction between the emulsion droplets and skin could influence dermal/transdermal delivery of the active
The effects of emulsifiers and emulsion formulation types on dermal and transdermal drug delivery
No full textEmulsions are widely used in the cosmetic and pharmaceutical fields for the topical administration of hydrophilic and lipophilic active ingredients. There exist different types of emulsions, e.g. water-in-oil, oil-in-water, water-in-oil-in-water and oil-in-water-in-oil. Furthermore, emulsions are thermodynamically unstable and necessitate an emulsifier for the formation and stabilisation. Both, the type of emulsion and emulsifier could affect dermal and transdermal delivery, which has been reviewed in this chapter. Due to the complexity of topical emulsions and consequently the difficulty to investigate the exclusive effect of emulsifiers and emulsion type on skin absorption, as other emulsion ingredients may also contribute to interactions with the active ingredient and the skin, this chapter aimed at focusing mainly on studies with a systematic approach. For example, studies were included that investigated emulsions with the same composition and only differed in the emulsifier component or emulsion type. The review demonstrated that the type of emulsion significantly affected the dermal and transdermal delivery. In general, skin penetration of hydrophilic active ingredients was enhanced when the active was incorporated into the continuous phase of the emulsion. Furthermore, multiple o/w/o emulsions, in comparison to simple w/o emulsions, reduced the transdermal delivery of lipophilic active ingredients, whereas the dermal delivery was increased. Therefore, multiple emulsions could be useful for prolonged topical delivery. It was also demonstrated that the effect of the emulsifiers on dermal and transdermal delivery could vary, depending on the structure and physicochemical properties of the emulsifier/emulsifier system, such as the hydrophilic chain length, hydrophilic-lipophilic balance (HLB) value, emulsifier charge or solid particles vs. surfactan
Breaching the skin barrier through temperature modulations
No full textThe impermeability of the stratum corneum often hinders the transport of molecules across the skin. Temperature modulations in the skin and the application of local heat both have the potential of circumventing this problem temporarily and reversibly and when applied, may aid in enhancing drug diffusion through the skin. A controlled and precise application of heat has the ability to create a cascade of events in the skin and thus aids in facilitating a faster movement of molecules into and across the skin. Possible mechanisms of enhancing drug permeation include: a) increase in drug diffusivity in the vehicle and/or in the skin, b) increase in partitioning and diffusion, c) disturbance in the lipid structure of the stratum corneum, and d) increased local blood flow. These mechanisms may operate individually or concurrently. The creation of micropores or channels in response to exposure to very high heat energy for a fraction of time is another technique that can facilitate the transport, known as thermal ablation.These micropores then serve as channels from where drug molecules can escape from formulations into the skin at a much faster rate than through passive diffusion. This review, therefore, summarises the effects that temperature modulations may have on the permeability of the skin. Physical techniques of heat induced skin ablation, such as chemical heating, thermoporation, radiofrequency induced thermal ablation, and laser induced thermal ablation are also presented in this review
Bioactive albumin-based carriers for tumour chemotherapy
No full textProteins are posed as the natural counterpart of the synthetic polymers for the development of drug delivery systems and few of them, have been regarded safe for drug delivery purposes by the United States Food and Drug Administration (FDA). Serum albumin is the most abundant protein in human blood. Interest in the exploration of pharmaceutical applications of albumin-based drug delivery carriers, especially for the delivery of chemotherapeutic agents, has increased in recent years. Albumin has several advantages over synthetic polymers, as it is biocompatible, biodegradable, has low cytotoxicity and has an excellent binding capacity with various drugs. Micro- and nano-carriers not only protect active pharmaceutical ingredients against degradation, but also offer a prolonged release of drugs in a controlled fashion. Since existing tumour chemotherapeutic agents neither target tumour cells, nor are they specific to tumour cells, a slow release of drugs from carriers would be beneficial in targeting carcinogenic cells intracellularly. This article aims at providing an overview of pharmaceutical applications of albumin as a drug delivery carrier in tumour chemotherap
Topical delivery of roxithromycin solid-state forms entrapped in vesicles
No full textRecently, considerable interest developed in using newer/improved antibiotics for the treatment of Acne vulgaris. During this study, different roxithromycin solid-state forms (i.e. crystalline and amorphous) were encapsulated into vesicle systems (niosomes, proniosomes, ufosomes and pro-ufosomes) for dermis targeted delivery. Characterization of the vesicles was done with transmission electron microscopy, light microscopy, droplet size, droplet size distribution, pH, zeta-potential and entrapment efficiency percentage. Finally, comparative release and topical diffusion studies were performed, to evaluate if targeted topical delivery was obtained and if the roxithromycin solid-state amorphous forms resulted in improved topical delivery. Vesicle systems containing different roxithromycin (2%) solid-state forms were successfully prepared and characterized. The vesicles showed optimal properties for topical delivery. All carrier systems had topical delivery to the epidermis-dermis, whilst no roxithromycin was found in the receptor compartment or stratum corneum-epidermis. The niosomes were the leading formulation and the two amorphous forms had better topical delivery than the crystalline form. Successful targeted delivery of roxithromycin was obtained in the dermis, where the activity against Propionibacterium acnes is needed. The amorphous forms seemed to have held their solid-state form during formulation and in the vesicles, showing improved topical delivery in comparison to the crystalline for
Whey protein/polysaccharide-stabilized oil powders for topical application: release and transdermal delivery of salicylic acid from oil powders compared to redispersed powders
No full textOil-in-water (o/w) emulsions are commonly converted into solid-like powders in order to
improve their physical and chemical stabilities. The aim of this study was to investigate whether whey
protein/polysaccharide-stabilized o/w emulsions could be converted into stable oil powders by means
of freeze-drying. Moreover, during this study, the effects of pH and polymer type on release and
trans(dermal) delivery of salicylic acid, a model drug, from these oil powders were investigated and
compared to those of the respective template emulsions and redispersed oil powders. Physical
characterization of the various formulations was performed, such as droplet size analysis and oil
leakage, and relationships drawn with regards to release and trans(dermal) delivery. The experimental
outcomes revealed that the oil powders could be redispersed in water without changing the
release characteristics of salicylic acid. pH and polymer type affected the release of salicylic acid
from the oil powders, template emulsions, and redispersed powders similarly. Contrary, the transdermal
delivery from the oil powders and from their respective redispersed oil powders was differently
affected by pH and polymer type. It was hypothesized that the release had been influenced by the
electrostatic interactions between salicylic acid and emulsifiers, whereas the transdermal performance
could have been determined by the particle or aggregate sizes of the formulationsNorth-West University, South Afric
Synthesis and transdermal properties of acetylsalicylic acid and selected esters
No full textThe primary aim of this study was to determine the transdermal penetration of acetylsalicylic acid and some of its derivatives, to establish a correlation, if any, with selected physicochemical properties and to determine if transdermal application of acetylsalicylic acid and its derivatives will give therapeutic drug concentrations with respect to transdermal flux. Ten derivatives of acetylsalicylic acid were prepared by esterification of acetylsalicyloyl chloride with ten different alcohols. The experimental aqueous solubility, log D and transdermal flux values were determined for acetylsalicylic acid and its derivatives at pH 4.5. In vitro penetration was measured through excised female human abdominal skin in diffusion cells. The experimental aqueous solubility of acetylsalicylic acid (6.56 mg/ml) was higher than that of the synthesised acetylsalicylate derivatives (ranging from 1.76 x 10−3 to 3.32 mg/ml), and the log D of acetylsalicylic acid (−0.85) was lower than that of its derivatives (ranging from −0.25 to 1.95). There was thus an inverse correlation between the aqueous solubility data and the log D values. The experimental transdermal flux of acetylsalicylic acid (263.83 nmol/cm2 h) was much higher than that of its derivatives (ranging from 0.12 to 136.02 nmol/cm2 h)
Cutaneous tuberculosis overview and current treatment regimens
No full textTuberculosis is one of the oldest diseases known to humankind and it is currently a worldwide threat
with 8e9 million new active disease being reported every year. Among patients with co-infection of the
human immunodeficiency virus (HIV), tuberculosis is ultimately responsible for the most deaths.
Cutaneous tuberculosis (CTB) is uncommon, comprising 1e1.5% of all extra-pulmonary tuberculosis
manifestations, which manifests only in 8.4e13.7% of all tuberculosis cases.
A more accurate classification of CTB includes inoculation tuberculosis, tuberculosis from an endogenous
source and haematogenous tuberculosis. There is furthermore a definite distinction between true
CTB caused by Mycobacterium tuberculosis and CTB caused by atypical mycobacterium species. The lesions
caused by mycobacterium species vary from small papules (e.g. primary inoculation tuberculosis) and
warty lesions (e.g. tuberculosis verrucosa cutis) to massive ulcers (e.g. Buruli ulcer) and plaques (e.g.
lupus vulgaris) that can be highly deformative.
Treatment options for CTB are currently limited to conventional oral therapy and occasional surgical
intervention in cases that require it. True CTB is treated with a combination of rifampicin, ethambutol,
pyrazinamide, isoniazid and streptomycin that is tailored to individual needs. Atypical mycobacterium
infections are mostly resistant to anti-tuberculous drugs and only respond to certain antibiotics. As in the
case of pulmonary TB, various and relatively wide-ranging treatment regimens are available, although
patient compliance is poor. The development of multi-drug and extremely drug-resistant strains has also
threatened treatment outcomes. To date, no topical therapy for CTB has been identified and although
conventional therapy has mostly shown positive results, there is a lack of other treatment regimensSouth African
Medical Research Council (Flagship program MalTB Redox), the
Centre of Excellence for Pharmaceutical Sciences, Faculty of Health
Sciences, North-West University, South Africa; National Research Foundation of South-Africa (CPRR13091742482
Sinigrin and Its Therapeutic Benefits
Full text linkSinigrin (allyl-glucosinolate or 2-propenyl-glucosinolate) is a natural aliphatic glucosinolate present in plants of the Brassicaceae family, such as broccoli and brussels sprouts, and the seeds of Brassica nigra (mustard seeds) which contain high amounts of sinigrin. Since ancient times, mustard has been used by mankind for its culinary, as well as medicinal, properties. It has been systematically described and evaluated in the classical Ayurvedic texts. Studies conducted on the pharmacological activities of sinigrin have revealed anti-cancer, antibacterial, antifungal, antioxidant, anti-inflammatory, wound healing properties and biofumigation. This current review will bring concise information about the known therapeutic activities of sinigrin. However, the information on known biological activities is very limited and, hence, further studies still need to be conducted and its molecular mechanisms also need to be explored. This review on the therapeutic benefits of sinigrin can summarize current knowledge about this unique phytocompounds
Quantitative determination of octadecenedioic acid in human skin and transdermal perfusates by gas chromatography-mass spectrometry.
No full textA gas chromatographic (GC) method with mass spectrometric (MS) detection is developed and validated for the accurate and precise determination of octadecenedioic acid (C18:1 DIOIC) in human skin samples and transdermal perfusates. C18:1 DIOIC is extracted using methanol. The saturated analogue 1,18-octadecanedioic acid (C18:0 DIOIC) is added as internal standard. Prior to analysis, both compounds are converted to their trimethylsilylated derivatives using N,O-bis(trimethylsilyl)trifluoroacetamide with 15% trimethylchlorosilane. Quantitation is performed in selected ion monitoring mode with a limit of quantitation of 250 ng/mL. Linearity with a correlation coefficient of 0.998 is obtained over a concentration range of 250-2000 ng/mL. Values for within-day accuracy range from 94.5% to 102.4%, and from 97.5% to 105.8% for between-day accuracy. Within- and between-day precision values are better than 5% and 7%, respectively. The recovery values from the various matrices vary from 92.6% to 104.0%. The GC-MS method is employed for the determination of C18:1 DIOIC after application of an emulsion containing the active ingredient onto human skin in vitro. The results demonstrate that the method is suitable for the determination of C18:1 DIOIC in human skin samples and transdermal perfusate
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