Enhanced percutaneous absoption of piroxicam via salt formation with ethanolamines

A Perspective on the Permeability of Cocrystals/Organic Salts of Oral Drugs

According to the BCS classification system, the differentiation of drugs is based on two essential parameters of solubility and permeability, meaning the latter is as pivotal as the former in creating marketable pharmaceutical products. Nevertheless, the indispensable role of permeability in pharmaceutical cocrystal profiles has not been sufficiently cherished, which can be most probably attributed to two principal reasons. First, responsibility may be on more user-friendly in vitro measurement procedures for solubility compared to permeability, implying the permeability measurement process seems unexpectedly difficult for researchers, whereas they have a complete understanding of solubility concepts and experiments. Besides, it may be ascribed to the undeniable attraction of introducing new crystal-based structures which mostly leaves the importance of improving the function of existing multicomponents behind. Bringing in new crystalline entities, to rephrase it, researchers have a fairly better chance of achieving high-class publications. Although the Food and Drug Administration (FDA) has provided a golden opportunity for pharmaceutical cocrystals to straightforwardly enter the market by simply considering them as derivatives of the existing active pharmaceutical ingredients, inattention to assessing and scaling up permeability which is intimately linked with solubility has resulted in limited numbers of them in the global pharmaceutical market. Casting a glance at the future, it is apprehended that further development in the field of permeability of pharmaceutical cocrystals and organic salts requires a meticulous perception of achievements to date and potentials to come. Thence, this perspective scrutinizes the pathway of permeation assessment making researchers confront their fear upfront through mapping the simplest way of permeability measurement for multicomponents of oral drugs.

Cyclodextrin Multicomponent Complexes: Pharmaceutical Applications

Cyclodextrins (CDs) are naturally available water-soluble cyclic oligosaccharides widely used as carriers in the pharmaceutical industry for their ability to modulate several properties of drugs through the formation of drug-CD complexes. The addition of an auxiliary substance when forming multicomponent complexes is an adequate strategy to enhance complexation efficiency and to facilitate the therapeutic applicability of different drugs. This review discusses multicomponent complexation using amino acids; organic acids and bases; and water-soluble polymers as auxiliary excipients. Special attention is given to improved properties by including information on the solubility, dissolution, permeation, stability and bioavailability of several relevant drugs. In addition, the use of multicomponent CD complexes to enhance therapeutic drug effects is summarized.

Preparation of starch macrocellular foam for increasing the dissolution rate of poorly water-soluble drugs

Starch macrocellular foam (SMF), a novel natural bio-matrix material, was prepared by the hard template method in order to improve the dissolution rate and oral bioavailability of poorly water-soluble drugs. Nitrendipine (NDP) was chosen as a model drug and was loaded into SMF by the solvent evaporation method. SMF and the loaded SMF samples (NDP-SMF) were characterized by scanning electron microscopy, differential scanning calorimetry, X-ray powder diffraction and Fourier transform infrared spectroscopy. In vitro drug release studies showed that SMF significantly increased the dissolution rate of NDP. In vivo studies showed that the NDP-SMF tablets clearly increased the oral bioavailability of NDP in comparison with the reference commercial tablets. All the results obtained demonstrated that SMF was a promising carrier for the oral delivery of poor water-soluble drugs.

Enhancing Skin Permeation of Biphenylacetic Acid (BPA) Using Salt Formation with Organic and Alkali Metal Bases

In the present study, a series of organic and alkali metal salts of biphenylacetic acid (BPA) have been prepared and evaluated in vitro for percutaneous drug delivery. The physicochemical properties of BPA salts were determined using solubility measurements, DSC, and IR. The DSC thermogram and FTIR spectra confirmed the salt formation with organic and alkali metal bases. Among the series, salts with organic amines (ethanolamine, diethanolamine, triethanolamine, and diethylamine) had lowered melting points while the alkali metal salt (sodium) had a higher melting point than BPA. The in vitro study showed that salt formation improves the physicochemical properties of BPA, leading to improved permeability through the skin. Amongst all the prepared salts, ethanolamine salt (1b) showed 7.2- and 5.4-fold higher skin permeation than the parent drug at pH 7.4 and 5.0, respectively, using rat skin.

Intermolecular hydrogen transfer and solubility tuning in multi-component molecular crystals of the API piroxicam

Twelve multi-component molecular crystals of the active pharmaceutical ingredient (API) piroxicam (PX) are described contrasting those with basic N-heterocycles with those formed with strong haloanilic acids. The effect on the solubility of this API is discussed, with evidence of enhanced solubility in the multi-component crystals formed.

A surrogate for topical delivery in human skin: silicone membranes

We have identified, for any surrogate membrane and human skin in vitro, the maximum flux through the membrane (output) should be measured if a correlation between the two is to be obtained. We also identified from an analysis of the passive permeation process that molecular weight, lipid and aqueous solubilities (which are easily measured) constitute the physicochemical properties of the active (input), upon which prediction of flux through the surrogate membrane and through skin in vitro should be based. Besides providing the bases for predicting flux, changes in these physicochemical properties can be easily implemented by those wishing to optimize new cosmetics or topical products. Maximum flux values through silicone membrane (n = 70) and through human skin in vitro (n = 52) have been collected and a good correlation between the flux through human skin in vitro and flux through silicone membrane (for the same molecules) was found.

Diclofenac Salts, VIII. Effect of the Counterions on the Permeation through Porcine Membrane from Aqueous Saturated Solutions

The following bases: monoethylamine (EtA), diethylamine (DEtA), triethylamine (TEtA), monoethanolamine (MEA), diethanolamine (DEA), triethanolamine (TEA), pyrrolidine (Py), piperidine (Pp), morpholine (M), piperazine (Pz) and their N-2-hydroxyethyl (HE) analogs were employed to prepare 14 diclofenac salts. The salts were re-crystallized from water in order to obtain forms that are stable in the presence of water. Vertical Franz-type cells with a diffusional surface area of 9.62 cm2 were used to study the permeation of these diclofenac salts from their saturated solutions through an internal pig ear membrane. The receptor compartments of the cells contained 100 mL of phosphate buffer (pH 7.4); a saturated solution (5 mL) of each salt was placed in the donor compartment, thermostated at 37 °C. Aliquots were withdrawn at predetermined time intervals over 8 h and then immediately analyzed by HPLC. Fluxes were determined by plotting the permeated amount, normalized for the membrane surface area versus time. Permeation coefficients were obtained dividing the flux values J by the concentration of the releasing phase-that is, water solubility of each salt. Experimental results show that fluxes could be measured when diclofenac salts with aliphatic amines are released from a saturated aqueous solution. Different chemical species (acid, anion, ion pairs) contribute to permeation of the anti-inflammatory agent even though ion-pairs could be hypothesized to operate to a greater extent. Permeation coefficients were found higher when the counterion contains a ring; while hydroxy groups alone do not appear to play an important role, the ring could sustain permeation, disrupting the organized domains of the membrane.

The control of skin-permeating rate of bisoprolol by ion-pair strategy for long-acting transdermal patches

A moderate drug permeating rate (flux) is desirable for long-acting transdermal patches. In this work, a novel simple method of controlling bisoprolol (BSP) flux by ion-pair strategy was initiated. Different ion-pair complexes including bisoprolol maleate (BSP-M), bisoprolol tartarate, bisoprolol besilate, and bisoprolol fumarate were prepared and their fluxes through rabbit abdominal skin were determined separately in vitro. Furthermore, permeation behavior from isopropyl myristate, solubility index in pressure-sensitive adhesives, determined by DSC, and n-octanol/water partition coefficient (log P) were investigated to illustrate the mechanism of drug permeation rate controlling. The results showed that compared to free BSP (J = 25.98 ± 2.34 μg/cm(2)/h), all BSP ion-pair complexes displayed lower and controllable flux in the range of 0.11 to 4.19 μg/cm(2)/h. After forming ion-pair complexes, the capability of BSP to penetrate through skin was weakened due to the lowered log P and increased molecule weight. Accordingly, this study has demonstrated that the flux of BSP could be controlled by ion-pair strategy, and among all complexes investigated, BSP-M was the most promising candidate for long-acting transdermal patches.

Effects of amines on percutaneous absorption of alendronate

OBJECTIVE

The aim of this study was to examine the effects of amines on the permeation of alendronate using solution formulations and pressure-sensitive adhesive (PSA) transdermal delivery systems (TDS).

MATERIALS AND METHODS

Monoethanolamine (MEA), diethanolamine (DEA), triethanolamine (TEA), diethylamine (DEYA), and triethylamine (TEYA) at concentrations of 3, 6, and 10% were added to propylene glycol (PG) containing 6% caprylic acid. In vitro and in vivo experiments were conducted using alendronate solution and PSA TDS formulations.

RESULTS

When using saturated solution formulations, 3% TEA and 10% DEYA showed high permeation rates of 8.20 ± 0.80 and 7.87 ± 0.18 μg/cm(2)/h, respectively. The maximum permeation flux of 1.79 ± 0.28 μg/cm(2)/h from 1 mg/ml solution was obtained with the addition of 10% DEYA followed by the addition of 10% TEYA (1.72 ± 0.72 μg/cm(2)/h). The highest enhancement factor of 1.86 was obtained with alendronate PSA TDS containing 10% MEA compared with no amine. In the in vivo study, the amount remaining to be excreted (ARE) at time 0 (Ae(∞)) and ARE at time t [Ae(t)] differed between TDS and oral delivery significantly (P < 0.01). The TDS containing 10% MEA showed the highest Ae(∞) (19.5 ± 6.93 μg), which was 2.7- and 2.2-fold, compared with oral and no amine administration, respectively.

CONCLUSION

Based on the results, TDS with 10% MEA in PG containing 6% caprylic acid could be a good candidate for the alendronate TDS.

Topical piroxicam in vitro release and in vivo anti-inflammatory and analgesic effects from palm oil esters-based nanocream

INTRODUCTION

During recent years, there has been growing interest in use of topical vehicle systems to assist in drug permeation through the skin. Drugs of interest are usually those that are problematic when given orally, such as piroxicam, a highly effective anti-inflammatory, anti-pyretic, and analgesic, but with the adverse effect of causing gastrointestinal ulcers. The present study investigated the in vitro and in vivo pharmacodynamic activity of a newly synthesized palm oil esters (POEs)-based nanocream containing piroxicam for topical delivery.

METHODS

A ratio of 25:37:38 of POEs: external phase: surfactants (Tween 80:Span 20, in a ratio 80:20), respectively was selected as the basic composition for the production of a nanocream with ideal properties. Various nanocreams were prepared using phosphate-buffered saline as the external phase at three different pH values. The abilities of these formulae to deliver piroxicam were assessed in vitro using a Franz diffusion cell fitted with a cellulose acetate membrane and full thickness rat skin. These formulae were also evaluated in vivo by comparing their anti-inflammatory and analgesic activities with those of the currently marketed gel.

RESULTS

After eight hours, nearly 100% of drug was transferred through the artificial membrane from the prepared formula F3 (phosphate-buffered saline at pH 7.4 as the external phase) and the marketed gel. The steady-state flux through rat skin of all formulae tested was higher than that of the marketed gel. Pharmacodynamically, nanocream formula F3 exhibited the highest anti- inflammatory and analgesic effects as compared with the other formulae.

CONCLUSION

The nanocream containing the newly synthesized POEs was successful for trans-dermal delivery of piroxicam.

Influence of cyclodextrin complexation with NSAIDs on NSAID/cold stress-induced gastric ulceration in rats

The aim of this work was to study the ability of beta-cyclodextrin (beta-CD) or hydroxypropyl beta-cyclodextrin (HP-beta-CD) to ameliorate the induction of gastric ulcers by a nonsteroidal anti-inflammatory drug, indomethacin or piroxicam, in rats exposed to restraint and hypothermic stress at 4 degrees C. Using oral gavage, rats fasted for 72 h were administered the equivalent of a 100 mg/kg dose of the assigned drug, alone or with the designated cyclodextrin (CD). The rats were placed in suitable rodent restrainers and then placed inside a ventilated refrigerator maintained at a temperature of 4 degrees C. Six hours later, each animal was removed, anaesthetized with ether, and the abdomen opened. Each stomach was removed, opened along the greater curvature and gently rinsed with isotonic saline solution. The induced gastric ulcers were examined and assessed with the help of a 10x binocular magnifier. Pronounced and marked gastric ulceration with complete loss of the mucosa, extensive deposition of fibrin and dense neutrophilic infiltrate were observed in rats treated with each of the drugs alone. Treatment with indomethacin or piroxicam alone induced ulcer indices of 26 +/- 2.3 or 14 +/- 1.8, respectively. However, beta-CD and HP-beta-CD each significantly suppressed ulceration due to restraint and cold stress. Rats treated with indomethacin or piroxicam in the presence of either beta-CD or HP-beta-CD exhibited normal tissues. Therefore, beta-CD and HP-beta-CD act as protective agents against gastrointestinal disorders produced by restraint and cold stress, even with the added stress from administration of either indomethacin or piroxicam.

Diclofenac Salts. V. Examples of Polymorphism among Diclofenac Salts with Alkyl-hydroxy Amines Studied by DSC and HSM

Nine diclofenac salts prepared with alkyl-hydroxy amines were analyzed for their properties to form polymorphs by DSC and HSM techniques. Thermograms of the forms prepared from water or acetone are different in most cases, suggesting frequent examples of polymorphism among these salts. Polymorph transition can be better highlighted when analysis is carried out by thermo-microscopy, which in most cases made it possible to observe the processes of melting of the metastable form and re-crystallization of the stable one. Solubility values were qualitatively related to the crystal structure of the salts and the molecular structure of the cation.

An investigation into the influence of counterion on the RS-propranolol and S-propranolol skin permeability

The effects of two contra-ions, namely benzoate (Bz) and oleate (Ol), on the in vitro human skin permeability of propranolol racemate (RS-PR) or S-enantiomer (S-PR) were studied. Saline solution (SS) or mineral oil (MO) were selected as vehicles. The MO increased the permeability coefficient (K(p)) of PR-Bz (pK(p) approximately 4) of about four times with respect to SS (pK(p) approximately 8) probably due to the ion pair formation. The steady-state flux of S-enantiomers resulted about twofold higher than that of racemates according to their lower melting temperatures with the exception of (S)-PR-Ol and (RS)-PR-Ol vehicled in SS which not resulted statistically different. This anomalous result could be explained considering the behavior of (RS)-PR-Ol or (S)-PR-Ol in aqueous solutions: these salts formed ion pairs which associated to form aggregates up to a concentration of 20 microg/mL as verified by light scattering. Therefore, their effective concentrations in SS resulted similar and justified the overlapped skin permeation profiles. All three considered variables, namely counterion, vehicle, and chirality, resulted mutually interfering on and deeply influenced the passive diffusion process of PR.

Study of ascorbic acid interaction with hydroxypropyl-beta-cyclodextrin and triethanolamine, separately and in combination

Complexation between ascorbic acid, hydroxypropyl-beta-cyclodextrin (HP-beta-CD) and triethanolamine (TEA), separately and in combination, was studied in solution and solid state. The freeze-drying method was used to prepare solid complexes, while physical mixtures being obtained by simple blending. These complexes were characterized in the solid state using differential scanning calorimetry (DSC) and infrared spectroscopy (IR). Nuclear magnetic resonance spectroscopy ((1)H and (13)C NMR) was used in aqueous solutions to obtain information about the mode of interaction. The degradation rate of each complex in solution was determined, and the stability constant of the complexes and the degradation rate of the ascorbic acid within the complexes were obtained. NMR studies provided clear evidence of partial inclusion into the HP-beta-CD cavity, but the stability constant value was very small indicating a weak host-guest interaction. The influence of complexation on the degradation rate of ascorbic acid was evaluated, and the data obtained showed a pronounced enhancement of aqueous stability with the TEA association complex, while this effect was lower with the HP-beta-CD inclusion complex. NMR experiments showed evidence of the formation of aggregates.

The effect of meloxicam/ethanolamine salt formation on percutaneous absorption of meloxicam

This study was undertaken to prepare meloxicam-ethanolamine salts (MX-EAs) that enhance the transdermal delivery of meloxicam. The physicochemical properties of MX-EAs were investigated by solubility measurements, Differential Scanning Calorimetry (DSC), and Infrared Spectroscopy (FT-IR). The DSC thermogram and FTIR spectra indicated that meloxicam formed salts with ethanolamines. The effects of various vehicles on the percutaneous absorption of meloxicam and of its salts across hairless mouse skin were evaluated using a flow-through diffusion cell system at 37 degrees C. Salt formation lowered the melting point of meloxicam and slightly reduced its octanol/water partition coefficient. Meloxicam-monoethanolamine salt (MX-MEA) and meloxicam-diethanolamine salt (MX-DEA) had greater solubilities and transdermal permeation rates across hairless mouse skin than meloxicam alone in various vehicles. Moreover, although the solubility of meloxicam-triethanolamine salt (MX-TEA) was generally lower than that of meloxicam, its permeation rate across the skin was higher. The fluxes of meloxicam and its salts were generally lower than those of piroxicam.

Evaluation of DNA damage induced by atrazine and atrazine-based herbicide in human lymphocytes in vitro using a comet and DNA diffusion assay

Atrazine is one of the most widely used herbicides in the world. When applied, it is not used as a pure active ingredient but in the form of commercial formulations. Besides atrazine, these formulations contain other substances that might represent a risk to human health due to their mutual interactions. We evaluated the genotoxicity, apoptosis and necrosis induction of atrazine as an active ingredient, the commercial formulation Gesaprim, and a Gesaprim adjuvant mixture without atrazine by comet and DNA diffusion assay, respectively. Human lymphocytes were treated for 0.5, 1, 3, 5, and 8 h with 0.047 microg/ml, 0.47 microg/ml, 4.7 microg/ml of substances tested both in the presence and in the absence of an exogenous metabolic activator. Atrazine did not appear to be genotoxic or to be capable of inducing apoptosis or necrosis. Unlike atrazine, Gesaprime and the adjuvant mixture increased DNA damage in lymphocytes. After 5 h of treatment, it also increased the number of apoptotic cells. Metabolic activation additionally enhanced the DNA-damaging potential of Gesaprim and the adjuvant mixture but did not affect atrazine genotoxicity. Thus, both assay endpoints differed significantly for the active ingredient and formulation. To evaluate the potential health risk of simultaneous exposure to adjuvants and an active ingredient, further efforts using a biomonitoring approach should be made.

Trials of clear aceclofenac-loaded soft capsules with accelerated oral absorption in human subjects

To develop an effective oral drug delivery system with accelerated absorption in human subjects for a poorly water-soluble acelofenac, five aceclofenac-loaded soft capsule preparations containing various ratios of different solubilizers were prepared and their dissolution tests were carried out. Among five preparations tested, a preparation with ethanolamine was selected as a formula of aceclofenac soft capsule (Korea United Pharm. Co. Ltd., Clanza S, since it was clear in appearance and showed the fastest dissolution rate due to the solubility-enhancing effect of aceclofenac. To evaluate and compare the pharmacokinetics of acelofenac-loaded soft capsules with the conventional aceclofenac tablets (Dae-Woong Pharm. Co. Ltd., Airtal) in human subjects; 14 normal healthy male volunteers (age 20-25 years old) were divided into two groups and a randomized 2 x 2 cross-over study was performed. Following oral administration of one tablet or capsule, each containing 100mg of aceclofenac, blood samples were collected at the predetermined time intervals and the concentration of aceclofenac in plasma was determined by HPLC method using UV detector. The AUC, Cmax, MRT, t1/2 and Kel of aceclofenac delivered from soft capsule were not significantly different from those from aceclofenac-loaded conventional tablet. However, soft capsule gave significantly higher initial concentration and significantly faster Tmax of aceclofenac than did conventional tablet, suggesting that the soft capsule with ethanolamine showed the faster absorption of aceclofenac in human subjects. Thus, the clear aceclofenac-loaded soft capsule with ethanolamine was a more effective oral dosage form with fast absorption for poorly water-soluble aceclofenac.

Effect of ethanolamine salts and enhancers on the percutaneous absorption of piroxicam from a pressure sensitive adhesive matrix

The effects of salt formation on the percutaneous absorption of piroxicam through hairless mouse skin from a pressure sensitive adhesive (PSA) matrix were investigated. We also studied the effect of permeation enhancers on the skin permeation of piroxicam or piroxicam-ethanolamine (PX-EA) salts from an acrylic adhesive matrix. The order of the permeation rates of piroxicam and PX-EA salts from the PSA matrix was piroxicam-monoethanolamine salt (PX-MEA)>piroxicam-diethanolamine salt (PX-DEA)>piroxicam>piroxicam-triethanolamine salt (PX-TEA). The enhancer Crovol A40 provided the highest piroxicam and PX-MEA fluxes and Plurol oleque the highest PX-DEA and PX-TEA fluxes. The order of piroxicam and PX-EA salts permeabilities were different for saturated solutions in various enhancers and PSA matrix containing the same enhancer, especially when Crovol A40, Crovol PK40 or Plurol oleque were used as enhancers. No close relationship was found between the fluxes of piroxicam or PX-EA salts from saturated solutions and from PSA matrices containing the same enhancer. Maximum piroxicam flux was obtained when PX-MEA/PX-TEA (4:6, v/v) was incorporated into a PSA matrix containing Crovol PK40.