The enhancement effect of surfactants on the penetration of lorazepam through rat skin

Lorazepam is an anxiolytic, antidepressant agent, having suitable feature for transdermal delivery. The percutaneous permeation of lorazepam was investigated in rat skin after application of a water:propylene glycol (50:50%v/v). The enhancing effects of various surfactants (sodium lauryl sulfate (SLS), cetyltrimethylammonium bromide (CTAB), benzalkonium chloride or Tween 80) with different concentrations on the permeation of lorazepam were evaluated using Franz diffusion cells fitted with rat skins. Flux, K_p, lag time and enhancement ratios (ERs) of lorazepam were measured over 24 h and compared with control sample. Furthermore, lorazepam solubility in presence of surfactants was determined. The in vitro permeation experiments with rat skin revealed that the surfactant enhancers varied in their ability to enhance the flux of lorazepam. The permeation profile of lorazepam in presence of the cationic surfactant, CTAB, reveals that an increase in the concentration of CTAB results in an increase in the flux of lorazepam in comparison with the control. But an increase in concentration of CTAB or benzalkounium chloride from 0.5 to 1% w/w or from 1 to 2.5% w/w resulted in a reduction in ER, respectively. Benzalkonium chloride which possessed the highest lipophilicity (log P=1.9) among cationic surfactants provided the greatest enhancement for lorazepam flux (7.66-fold over control) at 1% w/w of the surfactant. CTAB (log P<1) and sodium lauryl sulphate at a concentration of 5% w/w (the highest concentration) exhibited the greatest increase in flux of lorazepam compared with control (9.82 and 11.30-fold, respectively, over control). This is attributed to the damaging effect of the cationic and anionic surfactants on the skin at higher concentration. The results also showed that the highest ER was obtained in presence of 1% w/w surfactant with the exception of SLS and CTAB. The increase in flux at low enhancer concentrations is normally attributed to the ability of the surfactant molecules to penetrate the skin and increase its permeability. Reduction in the rate of transport of the drug present in enhancer systems beyond 1% w/w is attributed to the ability of the surfactant molecules to form micelles and is normally observed only if interaction between micelle and the drug occurs.     

The effect of structural QSAR parameters on skin penetration

We investigated the influence of mode of administration on the pharmacokinetics of a clinically used bisphosphonate, pamidronate, and of suberoylbisphosphonate (SuBP), a novel bisacylphosphonate of the P–CO–(C)_n–CO–P type, in rats. Serum drug levels and tissue disposition were determined following administration of the drugs by different modes: intravenous bolus (iso-osmotic and hypo-osmotic solutions), continuous intravenous infusion, and peroral administration. Results of the study indicate that the disposition of the bisphosphonates in soft tissue (liver, kidney and spleen) was dependent on route and rate of drug administration, and on the osmoticity of the vehicle. Consequently, main pharmacokinetic parameters (AUC, CL, and V_ss) were influenced by the mode of drug administration, precluding accurate determination of bioavailability from AUC values. On the other hand, bone and urine bisphosphonate accumulation were considerably less dependent on mode of administration, and, therefore, are recommended for bioavailability calculation.     

The effect of terpene concentrations on the skin penetration of diclofenac sodium

Terpenes and sesquiterpenes have been suggested as promising non-toxic, non-irritating transdermal penetration enhancers. This investigation aimed to study the effect of terpene concentration on the transdermal absorption of diclofenac sodium from ethanol:glycerin:phosphate buffer solution (60:10:30). Therefore, enhancing effects of various terpenes (menthone, limonenoxide, carvone, nerolidol and farnsol) with different concentrations (0.25, 0.5, 1, 1.5 and 2.5%, v/v) on the permeation of diclofenac sodium were evaluated using Franz diffusion cells fitted with rat skin. Furthermore, solubility of diclofenac sodium in the vehicle in presence of different concentrations of terpenes was determined. The results showed that despite the negligible effect of terpenes on the drug solubility, there was a profound skin penetration enhancement effect, although the terpene enhancers varied in their ability to enhance the flux of diclofenac sodium. The results showed that at the highest concentration of terpene (2.5%, v/v) the rank order of enhancement effect for diclofenac sodium was nerolidol>farnesol>carvone>methone>limonenoxide, whereas at the low concentration of 0.25% the rank order was farnesol>carvone>nerolidol>menthone>limonenoxide. No direct relationship existed between terpene concentration and the permeation rate. The most outstanding penetration enhancer was nerolidol, providing an almost 198-fold increase in permeability coefficient of diclofenac sodium, followed by farnesol with a 78-fold increase.     

促进剂对酮洛芬体外渗透性的影响

目的：考察酮洛芬的皮肤渗透性及３种促进剂月桂氮Ｚｈｕｏ酮、油酸和丙二醇对其皮肤渗透性的影响。方法：将不同浓度的药物及促进剂制成贴片,采用改进的Ｆｒａｎｚ扩散池,离体小鼠皮肤为透皮屏障,测定药物的体外渗透量。结果：酮洛芬随其药物浓度的增大,渗透增强;月桂氮Ｚｈｕｏ酮、油酸和丙二醇对其渗透性均有一定影响,其中５％油酸作用最强,丙二醇较弱;丙二醇与月桂氮Ｚｈｕｏ酮合用,能明显提高月桂氮Ｚｈｕｏ酮的促渗作     

Assessment of the percutaneous penetration of cisplatin: The effect of monoolein and the drug skin penetration pathway

It was intended to examine the in vitro penetration of cisplatin (CIS) through porcine skin in the presence of different concentrations of monoolein (MO) as well as to verify the main barrier for CIS skin penetration. In vitro skin penetration of CIS was studied from propylene glycol (PG) solutions containing 0%, 5%, 10%, and 20% of MO using Franz-type diffusion cell and porcine ear skin. Pretreatment experiments with MO and experiments with skin without stratum corneum (SC) were also carried out. Skin penetration studies of CIS showed that the presence of MO doubled the drug permeation through the intact skin. However, permeation studies through the skin without SC caused only a small enhancement of CIS permeation compared to intact skin. Moreover, pretreatment of skin with MO formulations did not show any significant increase in the flux of the drug. In conclusion, MO did not act as a real penetration enhancer for CIS, but it increased the drug partition to the receptor solution improving CIS transdermal permeation. The absence of improvement in drug permeation by MO pretreatment and by the removal of SC indicates that the SC is not the main barrier for the permeation of the metal coordination compound.     

Interactions of surfactants (edge activators) and skin penetration enhancers with liposomes

Incorporating edge activators (surfactants) into liposomes was shown previously to improve estradiol vesicular skin delivery; this phenomenon was concentration dependent with low or high concentrations being less effective. Replacing surfactants with limonene produced similar behaviour, but oleic acid effects were linear with concentration up to 16% (w/w), beyond which it was incompatible with the phospholipid. This present study thus employed high sensitivity differential scanning calorimetry to probe interactions of additives with dipalmitoylphosphatidylcholine (DPPC) membranes to explain such results. Cholesterol was included as an example of a membrane stabiliser that removed the DPPC pre-transition and produced vesicles with a higher transition temperature (T(m)). Surfactants also removed the lipid pre-transition but reduced T(m) and co-operativity of the main peak. At higher concentrations, surfactants also formed new species, possibly mixed micelles with a lower T(m). The formation of mixed micelles may explain reduced skin delivery from liposomes containing high concentrations of surfactants. Limonene did not remove the pre-transition but reduced T(m) and co-operativity of the main peak, apparently forming new species at high concentrations, again correlating with vesicular delivery of estradiol. Oleic acid obliterated the pre-transition. The T(m) and the co-operativity of the main peak were reduced with oleic acid concentrations up to 33.2mol%, above which there was no further change. At higher concentrations, phase separation was evident, confirming previous skin transport findings.     

The effect of prolonged exposure on sodium dodecyl sulfate penetration into human skin

The purpose of this study was to examine the effect of prolonged surfactant exposure on mechanisms of anionic surfactant penetration into human skin. A radiolabeled probe (14-carbon sodium dodecyl sulfate (¹⁴C-SDS)) was used to trace the penetration of a model anionic surfactant, sodium dodecyl sulfate (SDS), into excised human skin and into an inert membrane composite in vitro. SDS dose varied from 0.03 to 15 mg/cm², mimicking the exposure of a rinse-off cleanser on skin. Two surfactant exposure lengths were tested, 2 min and 5 h. SDS penetration into excised human skin was constant from 50 to 600 mM for skin samples exposed to SDS for 2 min. For skin samples exposed to SDS for 5 h, SDS penetration into skin increased log-linearly with increasing SDS concentration. SDS penetration into the inert membrane composite was constant from 50 to 600 mM SDS regardless of length of surfactant exposure. Penetration of the radiolabeled probe into skin and into the inert membrane correlated well with the monomeric concentration of the radiolabeled probe in the applied surfactant solution. These results support that monomer concentration is the driving force for initial SDS penetration into upper layers of the stratum corneum over a wide range of concentrations. With prolonged exposure, SDS penetrates the skin in a dose-dependent manner due to surfactant-induced damage to the skin.     

Synergistic effect of low-frequency ultrasound and surfactants on skin permeability.

Low-frequency ultrasound (20 kHz) and surfactants have been individually shown to enhance transdermal drug transport. In this study, we investigated the synergistic effect of ultrasound and surfactants on transdermal drug delivery. Surfactants with different head group chemistries including anionic, cationic, and nonionic with varying tail lengths (8-16-carbon atoms) were studied. We found that surfactants possessing anionic and cationic head groups were more potent than those possessing nonionic head groups in increasing skin conductivity in the presence of ultrasound. Furthermore, for surfactants possessing the same head group, those with a 14-carbon tail length were found to be most effective in enhancing skin permeability. The data presented in this report show that ultrasound and surfactants synergistically enhance skin permeability. Two mechanisms are shown to play a role in this synergistic effect. First, ultrasound enhances surfactant delivery (enhanced delivery) into the skin and, second, ultrasound disperses surfactant (enhanced dispersion) within the skin. In general, surfactants that are potent enhancers by themselves are potent enhancers in the presence of ultrasound as well. We performed imaging experiments to assess the effect of ultrasound on delivery of a model permeant, sulforhodamine B, into the skin. These experiments show that ultrasound enhances surfactant delivery and dispersion in the skin.     

The effect of diazepam on patients' memory

Ten patients who were prescribed daily doses of diazepam for the treatment of anxiety, insomnia, or psychosomatic symptoms were assessed repeatedly on measures of short-term and long-term memory on and off the drug. Both kinds of memory, especially the latter, appeared detrimentally affected by the drug. However, dosage seemed to be inversely related to the degree of memory impairment. In general, the results are consistent with the hypothesis that diazepam interferes with the memory consolidation process. The negative relationship between drug dosage and degree of memory impairment might be due to habituation toward this particular side effect by heavier drug users. It is suggested that on theoretical grounds, the use of diazepam in conjunction with the behavioral psychotherapies may be contraindicated.     

桉油对川芎嗪透过离体大鼠皮肤的促进作用

目的研究桉油对川芎嗪透皮吸收的促进作用及其最佳浓度。方法采用V-C水平扩散池,以流通量为指标,观察桉油及其在真空条件下分馏得到的各馏分和不同浓度的桉树脑对川芎嗪透过离体大鼠皮肤的促进作用。结果各馏分中以2%浓度的69.5~70℃馏分的促透效果最好,与1%、2%桉树脑的促透效果相当。结论桉油主成分桉树脑对川芎嗪透皮起主要促进作用,并以(1.45±0.04)%的浓度最佳。     

Evaluation of penetration enhancement of lidocaine by nonionic surfactants through hairless mouse skin in vitro

The effect of two nonionic surfactants (polyoxyethylene sorbitan monoesters) on percutaneous absorption of lidocaine in the presence of various concentrations of propylene glycol is reported. Comparisons were made in vitro using excised hairless mouse skin as the barrier membrane. Under infinite dose conditions, steady-state flux was enhanced by surfactants at high propylene glycol concentrations. The same trend was observed following application of a thin layer of formulation to the skin (finite-dose conditions). However, penetration behavior was complex due to: (a) changes in vehicle composition following application, (b) temperature changes resulting from evaporation or moisture uptake, and (c) depletion of lidocaine as a result of penetration with compositions that lost water by evaporation. Two peaks in the flux versus time curve were observed. Surfactant monomer concentration in the vehicles was increased in the presence of propylene glycol.     

The penetration of cefpiramide into the skin]

To investigate the skin penetration of cefpiramide (CPM, SM-1652), a broad-spectrum and long acting cephem antibiotic, 1 g of CPM was administered by single bolus intravenous injection to patients under general anesthesia during operations for full-thickness skin grafting. The CPM levels in both the serum and the skin were determined by bioassay at specified time intervals, and the following results were obtained. 1. Peak CPM concentrations in the serum (mean: 292.78 micrograms/ml) were observed 10 minutes after administration, and declined very slowly thereafter. 2. Peak CPM concentrations in the skin (mean: 23.05 micrograms/g) were observed 2 hours after administration, and then also declined very slowly. 3. The ratio of skin to serum concentrations was 16% when the peak CPM concentrations in the skin were obtained (2 hours after the administration). These results show that effective CPM concentrations were maintained in the skin for a long period, indicating a good therapeutic action against skin infections.     

The effect of penetration enhancers on permeation kinetics of nitrendipine in two different skin models

The purpose of this research was to evaluate the effect of penetration enhancers on permeation kinetics of nitrendipine (NTP) through two different skin models. The permeation profile and related kinetics parameters such as activity parameter, diffusion parameter, lag time, relative activity parameter and relative diffusion parameter of NTP was determined in presence of some novel and widely accepted permeation enhancers. Among all the more pronounced enhancing effect was obtained with oleic acid (OA) as it presented the highest permeability coefficient. The enhancement was found to be increased in the following order: Dimethyl sulphoxide (DMSO)相似文献   

The effect of glycyrrhizin on the release rate and skin penetration of diclofenac sodium from topical formulations

The influence of glycyrrhizin extracted from Glycyrrhiza glabra var. glandulifera (licorice roots) on the percutaneous absorption of diclofenac sodium from sodium carboxymethylcellulose (NaCMC) gels or oil-in-water (o/w) emulsion was investigated. Skin permeation experiments were carried out using excised abdominal rat skin. The results showed that the efficiency of glycyrrhizin as an enhancer agent is greater in gel formulations than it is in the emulsions. The enhancer with the concentration of 0.1% w/w in gel increased diclofenac sodium flux value to tenfold compared with the control gel.     

The effect of glycyrrhizin on the release rate and skin penetration of diclofenac sodium from topical formulations

The influence of glycyrrhizin extracted from Glycyrrhiza glabra var. glandulifera (licorice roots) on the percutaneous absorption of diclofenac sodium from sodium carboxymethylcellulose (NaCMC) gels or oil-in-water (o/w) emulsion was investigated. Skin permeation experiments were carried out using excised abdominal rat skin. The results showed that the efficiency of glycyrrhizin as an enhancer agent is greater in gel formulations than it is in the emulsions. The enhancer with the concentration of 0.1% w/w in gel increased diclofenac sodium flux value to tenfold compared with the control gel.     

The effect of diazepam on nociception in mice

The antinociceptive properties of diazepam were evaluated in mice, using four different pain tests and different doses of the drug (0.2, 0.5, 1.0 and 2.0 mg/kg). In the tail flick test and the increasing temperature hot plate test there were no effects. In the formalin test reduced licking was observed for the highest dose of diazepam. However, this dose also induced clear sedation possibly causing the reduced licking response. In the constant temperature hot plate test a hyperalgesia was found for all doses tested. This hyperalgesia was not observed in animals adapted to the test apparatus, suggesting that the "hyperalgesic" effect of diazepam may be due to reduced stress analgesia. The serum concentrations of the drug were comparable to therapeutic levels in humans. It was concluded that the sedative and anxiolytic effects of diazepam may influence the results of nociceptive tests, but the drug has probably no effect on nociception in itself.     

薄荷醇影响地西泮鼻腔吸收的药效学

目的:研究鼻腔给药的地西泮以及与薄荷醇配伍后的中枢抑制作用特点。方法:以鼻腔给药的方式建立小鼠模型,对鼻腔给药的地西泮及其与薄荷醇伍用后的镇静催眠及抗惊厥的中枢抑制作用效果进行评价。结果:与溶剂对照组相比,经鼻腔途径给药的地西泮能抑制电刺激和士的宁引起的惊厥发作并且增强戊巴比妥钠的镇静催眠作用,并与其同剂量腹腔给药的药效相近;薄荷醇在一定程度上能增强鼻腔给药的地西泮的药效。结论:地西泮经鼻腔给药能发挥镇静催眠和抗惊厥作用,药效与给药浓度成剂量-效应关系;鼻腔给予同剂量的地西泮与腹腔给药的药效相近;伍用薄荷醇后,地西泮的药效在一定程度上增强。     

Solubility of diazepam and prazepam in aqueous non-ionic surfactants

The solubility of diazepam and prazepam in aqueous polyoxyethylen-10-dodecanol, polyoxyethylen-23-dodecanol and polyoxyethylen-20-hexadecanol, has been determined at 25.0 degrees C. Diazepam seems to achieve a higher micellar penetration than prazepam, in spite of an expected smaller hydrophobic character. Thermodynamic interpretation of the micellar solutions is carried out using the regular solutions approach. A surfactant-independent relation between solubilities of both drugs has been derived.