Niacinamide (NIA) has been widely used in cosmetic and personal care formulations for several skin conditions. Permeation of topical NIA has been confirmed in a number of studies under infinite dose conditions. However, there is limited information in the literature regarding permeation of NIA following application of topical formulations in amounts that reflect the real-life use of such products by consumers. The aim of the present work was therefore to investigate skin delivery of NIA from single solvent systems in porcine skin under finite dose conditions. A secondary aim was to probe the processes underlying the previously reported low recovery of NIA following in vitro permeation and mass balance studies. The solubility and stability of NIA in various single solvent systems was examined.The solvents investigated included Transcutol® P (TC), propylene glycol (PG), 1-2 hexanediol (HEX), 1-2 pentanediol (1-2P), 1-5 pentanediol (1-5P), 1-3 butanediol (1-3B), glycerol (GLY) and dimethyl isosorbide (DMI). Skin permeation and deposition of the molecule was investigated in full thickness porcine skin in vitro finite dose Franz-type diffusion experiments followed by mass balance studies. Stability of NIA for 72 h in the solvents was confirmed. The solubility of NIA in the solvents ranged from 82.9 ± 0.8 to 311.9 ± 4.5 mg/mL. TC delivered the highest percentage permeation of NIA at 24 h, 32.6 ± 12.1 % of the applied dose. Low total recovery of NIA after mass balance studies was observed for some vehicles, with values ranging from 55.2 ± 12.8 % to 106.3 ± 2.3 %. This reflected the formation of a number of NIA degradation by-products in the receptor phase during the permeation studies. Identification of other vehicles for synergistic enhancement of NIA skin delivery will be the subject of future work.
Terbinafine (TBF) is commonly used in the management of fungal infections of the skin because of its broad spectrum of activity. Currently, formulations containing the free base and salt form are available. However, there is only limited information in the literature about the physicochemical properties of this drug and its uptake by the skin. In this work, we conducted a comprehensive characterisation of TBF, and we also examined its percutaneous absorption in vitro in porcine skin. TBF-free base was synthesised from the hydrochloride salt by a simple proton displacement reaction. Both the free base and salt form were further analysed using Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA). Delivery of TBF-free base in excised porcine skin was investigated from the following solvents: Isopropyl myristate (IPM), propylene glycol monolaurate (PGML), Transcutol® (TC), propylene glycol (PG), polyethylene glycol 200 (PEG 200), oleic acid (OL), ethanol (EtOH), and isopropyl alcohol (IPA). Permeation and mass balance studies confirmed that PG and TC were the most efficacious vehicles, delivering higher amounts of TBF-free base to the skin compared with a commercial gel (p < 0.05). These preliminary results are promising and will inform the development of more complex formulations in future work.
3-O-ethyl l-ascorbic acid (EA), an ether derivative of Vitamin C, is widely used in skincare formulations. Previously, we reported the effects of neat solvents on EA percutaneous absorption and observed that 0.6–7.5% of the applied EA was delivered through the skin over 24 h. In this work, we designed complex formulations using combinations of solvents that may act synergistically and examined their impact on EA permeation in porcine skin in vitro under finite dose conditions. Binary combinations of propylene glycol (PG) with propylene glycol monolaurate (PGML) were effective in enhancing skin permeation of EA compared with individual solvents (p < 0.05). Combining PGML with 1,2-hexanediol (HEX) did not result in significantly higher EA permeation compared with the neat solvents (p > 0.05). Addition of the volatile solvent isopropyl alcohol (IPA) to PG solutions also did not improve EA skin delivery compared with neat PG. Ternary solvent systems containing PG:PGML were subsequently prepared by the addition of a lipophilic solvent, either isopropyl myristate (IPM), medium-chain triglycerides (MCT) or isostearyl isostearate (ISIS). The optimum vehicle, PG:PGML:IPM, promoted up to 70.9% skin delivery of EA. The PG:PGML:ISIS vehicles also promoted EA permeation across the skin, but to a significantly lesser extent than the IPM-containing vehicles. No enhancement of EA delivery was noted for the PG:PGML:MCT mixtures. These results will inform the development of targeted formulations for EA in the future.
Concurrent administration of more than one drug is a common practice in medical science and in such case one drug may affect the pharmacology of another drug. Ciprofloxacin is a commonly used antibiotic in Bangladesh and frequently prescribed with paracetamol and zinc salt for concomitant use in patients suffering from infections. Therefore, the interaction of ciprofloxacin with paracetamol and zinc salt was studied in vitro at pH 1.2, 6.8 and 7.4 which are related to gastric, intestinal juices and blood environment, respectively. In vitro evaluation of ciprofloxacin complexes with paracetamol and zinc was carried on several gram positive and gram negative microorganisms by disc diffusion method. The in vivo effect of the complexes was assessed by determining the plasma concentration in mice by spectroscopic method. It was observed that in the in vitro study paracetamol and zinc has insignificant effect on the antibacterial activity of ciprofloxacin although zinc itself showed some antibacterial activity; and in the in vivo study it was found that zinc sulphate reduced the bioavailability of ciprofloxacin HCl.
Nandrolone is an anabolic steroid drug that increases production and urinary excretion of erythropoietin. The drug is indicated with calcium nitrate, magnesium sulfate and potassium permanganate as concomitant uses. Therefore, there is a chance of interactions during concomitant use. Hence, we evaluated the interactions monitored by UV, conductometric titration and Ardon's spectrophotometric methods of nandrolone with calcium nitrate, magnesium sulfate and potassium permanganate at the ratio of 1: 1 at different pHs. It was found that nandrolone did not form any stable complexes at the ratio of 1:1 with the above mentioned salts.
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