Skin penetration and tissue permeation after topical administration of diclofenac

Objective: Topical delivery of drugs is an alternative to oral administration, often with similar efficacy but potentially a more favorable tolerability profile. However, topical formulations need to be able to penetrate the skin and permeate to the target areas in quantities sufficient to exert a therapeutic effect. Many factors can affect this process, including the physicochemical properties of the drug, the formulation used, and the site and mode of application. It is believed that measurement of drug concentrations at the sites of action may be an indicator of their likely efficacy. This review addresses these issues, with reference to topically administered diclofenac in osteoarthritis.

Methods: Articles relevant to this review were identified after a systematic search of Medline and Embase, using the key words “diclofenac”, "topical administration" and “osteoarthritis” in the search strategy.

Results: The sparse data available indicate that topical diclofenac can penetrate and permeate to deeper tissues, with a lower plasma to tissue ratio than oral diclofenac. The tissue diclofenac levels after topical delivery are sustained over time (at least several hours). However, there is not enough data to establish how diclofenac levels in the joint compare with IC₅₀ levels (50% of the maximum inhibition of prostaglandin synthesis) established following oral administration.

Conclusions: After topical application, diclofenac can penetrate the skin and permeate to deeper tissues, where it reaches a concentration that appears to be sufficient to exert a therapeutic effect. More robust methods are required for in vivo characterization to better estimate the clinical efficacy of topically applied drugs.     

Pharmacokinetics of cefonicid in serum and its penetration into lung tissue, bronchial mucosa and pleura

Cefonicid pharmacokinetics in serum and tissue penetration into the lung parenchyma, bronchial mucosa and pleura were studied in 39 patients undergoing lung excision for malignancy. Cefonicid concentrations in serum and tissues samples were assayed at different times after a single 1 g intramuscular administration. The concentrations observed were much higher than the reported minimal inhibitory concentrations for the microorganisms commonly responsible for bronchial and pulmonary infections and therapeutic concentrations were still detectable in the tissues 24 h after dosing. Kinetic findings demonstrated a similar half-life for cefonicid in tissues and in serum. These data provided a further kinetic explanation for the observed clinical efficacy of cefonicid with a single daily dose.     

Calculation of the antibiotic level in the lung tissue and bronchial secretion with an oral controlled-release dosage form

The drug level-time history in plasma and lung tissue was calculated with an antibiotic orally delivered in either an immediate-release or a controlled-release dosage form. The drug profiles were compared with experiment results given in the literature. In the same way, the drug level was evaluated in the bronchial secretion in contact with lung tissue. A numerical model, based on finite differences taking all the known facts into account was built and tested with the data found in the literature. Transport of the drug was looked at, including a stage of diffusion through the thickness of the lung tissue and a stage of convection into the bronchial secretion. A few parameters were thus considered, including the thickness of the lung tissue and the diffusivity of the antiobiotic through the tissue, the thickness of the bronchial secretion and the coefficient of convective transport into the sputum which characterizes its viscosity. Two partition factors were also introduced for the drug: between the tissue and the serum and between the lung tissue and the bronchial secretion.     

家兔静注环丙沙星后血液与眼组织分布及其药代动力学研究

研究家兔静注环丙沙星 (CPL X)后血液与眼组织分布及药代动力学参数。用高效液相色谱法测定血液和眼内各组织中药物浓度。结果给药 30 min后泪液、角膜、房水、虹膜 -睫状体、晶状体和玻璃体组织内峰浓度值 (Cmax)分别为 (8.92± 2 .88)、(14 2 .84± 2 5 .0 2 )、(11.0 6± 2 .80 )、(99.32± 10 .6 0 )、(30 .2 8± 1.91)和(8.10± 1.71) μg/ ml或 μg/ g;其血液和各组织中消除半衰期 (T1 /2β)分别为 (1.2 1± 0 .2 3)、(1.4 8± 0 .97)、(1.6 6± 0 .13)、(2 .0 9± 0 .5 1)、(2 .0 1± 0 .4 4 )、(1.5 2± 0 .92 )和 (1.2 1± 0 .6 6 ) h。表明家兔静注 CPL X后能穿透到眼内各组织中。     

Pharmacokinetics and tissue distribution of chlorpheniramine in rabbits after intravenous administration

Intravenous studies of chlorpheniramine (CPM) were conducted in six New Zealand White male rabbits (mean wt. 3.88 kg). CPM and its two demethylated metabolites in arterial serum and urine were assayed by HPLC. Triexponential equations were needed to fit the i.V. CPM serum data in three rabbits, while biexponential equations were required in the other three rabbits. Harmonic mean of V₁, V_ss, V _area , CL,and terminal t _1/2 were 2.84, 10.8, and 15.5 liters/kg, and 4.14 liters/kg/hr and 2.57 hr, respectively. The average serum protein binding was 44%. The average blood to plasma concentration ratio was 1.85. Estimated mean hepatic blood extraction ratio based on i.v. studies was 0.88. Tissue distribution studies showed rapid and extensive uptake of CPM by various organs such as lung, kidneys, and brain after i.v. bolus injection, as their concentrations were 160-, 80-, and 31- fold higher than the plasma level. The amount of CPM in the muscle was calculated to represent about 50% of CPM present in the body near the steady state. Variation in plasma protein and tissue binding was postulated to be an important factor for the observed marked interspecies difference in the apparent volume of distribution of CPM. Only 2% of the dose was excreted unchanged in the urine.     

Spatial distribution of 8-methoxypsoralen penetration into human skin after systemic or topical administration

AIMS: Photochemotherapy employing psoralens combined with UVA irradiation (PUVA) is a standard therapy for a variety of dermatoses. Psoralens can be administered orally or topically in the form of bath or cream preparations. Recommendations for the time of UVA irradiation are mainly based on the time course of minimal phototoxic doses. However, the time course and depth of skin penetration of psoralens is not well characterized. METHODS: We assessed the time course of 8-MOP concentrations in horizontal epidermal and dermal skin sections in 10 patients undergoing oral (n = 3), cream (n = 4) and bath (n = 3) PUVA therapy. Punch biopsies (4 mm) were taken from "healthy" skin sites. A highly sensitive LC-MS-MS method was employed for 8-MOP analysis. RESULTS: Epidermal concentrations following cream or bath were highest at the end of the application period (time zero) when irradiation is performed. At this time, 8-MOP cream provided significantly higher epidermal concentrations (mean +/- s.e. mean 128.0 +/- 22.6 pg mm-3; 95% CI: 77.6, 178.4) than oral 8-MOP (27.0 +/- 25.3 pg mm-3; 95% CI: 29.3, 83.3 at 1 h; P = 0.025). Conversely, concentrations in the papillary dermis were significantly higher with oral 8-MOP (20.2 +/- 3.1 and 16.2 +/- 2.2 pg mm-3 at 1 and 2 h, respectively) than with 8-MOP cream (7.1 +/- 2.8 and 8.4 +/- 2.0 pg mm-3 time zero and 0.5 h, respectively; P = 0.020 and 0.045, respectively) or bath (8.8 +/- 3.1 and 7.7 +/- 2.2 pg mm-3; P = 0.050 and 0.039, respectively). The observed time courses of 8-MOP concentrations correspond to time courses of photosensitivity found previously with the different treatment modalities. CONCLUSIONS: The higher epidermal 8-MOP concentrations found after topical 8-MOP may explain the lower UVA doses needed with the topical route. These results suggest that topical 8-MOP may be superior in patients where the pathology is localized in the epidermis. In sclerosing diseases, which mainly affect the dermis oral PUVA might be advantageous because dermal concentrations are highest with this route of administration.     

肺癌病人动脉灌注和静滴环磷酰胺、阿霉素及顺铂联合用药的药物动力学比较

本文报道１５例肺癌病人应用ＣＡＰ方案化疗后通过测定环磷酰胺及其活性代谢物、阿霉素和顺铂的血药浓度，分别对两种不同途径给药后三种药物的药物动力学进行了比较。结果表明，三种药物支气管动脉灌注与静滴后的药动学特征均符合二室开放模型。支气管动脉灌注给药使药物清除率降低。可增加药物在体内及肺癌组织内的滞留时间，同时并不增加对肾脏的毒性。     

Simultaneous extraction of enrofloxacin and ciprofloxacin from chicken tissue by molecularly imprinted matrix solid-phase dispersion

An ofloxacin molecularly imprinted polymer was synthesized and used as a dispersant of matrix solid-phase dispersion for the determination of enrofloxacin and ciprofloxacin in chicken tissue. The selected dispersant shows high affinity to enrofloxacin and ciprofloxacin in aqueous environment and could selectively enrich them from chicken tissue matrix. The extract was sufficiently clean for further chromatographic analysis without interferences from template leakage or chicken tissue matrix. Linearity ranged from 0.03 to 200 μg/g with the correlation coefficient r² > 0.9993. The recoveries of spiked chicken tissues were in the range of 82.7–96.6% for enrofloxacin and 88.7–102% for ciprofloxacin.     

Antibiotic exposure at the site of infection: principles and assessment of tissue penetration

ABSTRACT

Introduction: Since the majority of bacterial infections occur at sites outside the bloodstream, antibiotic tissue concentrations are of significant relevance to optimize treatment. The aim of this review is to aid the clinician in choosing optimal regimens for the treatment of extravascular infections.

Areas covered: We discuss the principles of antibiotic tissue penetration and assess different approaches to obtain data on this subject. Finally, we present tissue penetration data for several relevant groups of antibiotic agents in a number of extravascular sites. Data were obtained from an extensive literature search in PubMed until February 2019.

Expert opinion: There is still a long way to go before reliable information about tissue penetration of antibiotics is sufficiently available to serve as a basis for the design of optimal strategies for drug and dose selection. At this moment, there is a lack of robust data on tissue penetration, where both the sampling and measurement techniques as well as the relationship between tissue concentrations and clinical outcome of antibiotic treatment have to be better defined.     

Changes in concentration of cefotetan in blood and lung tissue after intravenous administration

Cefotetan (CTT), a newly-developed cephamycin antibiotic, has been used widely for the treatment of various infectious diseases because of its excellent antibacterial potency and dynamic transport in vivo. Although the drug transfer to almost every organ, tissue, and body fluid has been studied, only a few reports are available regarding the transfer to lung tissue. In the present study, 1 g of CTT was intravenously injected in a single dose to each of 22 patients subjected to pulmonary resection. Subsequently, its concentrations in blood and lung tissue were measured in sequence. The degree of transfer of the drug to the lung tissue was calculated to evaluate the pharmacodynamics of CTT in vivo. The following results were obtained in this analysis. 1. The T1/2(beta) of the concentration in blood was 4.18 hours, and AUC0-infinity was 478.7 micrograms.hr/ml. 2. Cmax in the lung tissue was 31.5 micrograms/g, and Tmax was 0.83 hour, and tissue concentrations decreased in parallel to blood concentrations. CTT was transferred to the lung tissue to achieve high concentrations following an intravenous administration. Since high concentrations are maintained for a long period of time, this antibiotic is expected to exert an excellent effect in the prevention and the treatment of respiratory infections.     

Influence of the mode of intravenous administration on the penetration of ceftazidime into tissues and pleural exudate of rats.

The influence of the mode of intravenous (i.v.) administration (bolus injection or continuous infusion) on the tissue penetration of ceftazidime was studied in the rat. The antibiotic concentration was monitored in serum, pleural exudate, vitreous humor, kidney, liver, lung, testicles and epididymal fat tissue. Administration as a bolus resulted in a significantly higher AUC in pleural exudate and in higher peak levels in serum, liver and lung than continuous infusion, which produced a higher peak concentration in kidney than a bolus. No differences in AUC and peak concentrations between the two methods of administration were observed in the other tissues or fluids. With either method of administration the highest antibiotic accumulation was observed in kidney.     

In vitro and ex vivo methods predict the enhanced lung residence time of liposomal ciprofloxacin formulations for nebulisation

Liposomal ciprofloxacin formulations have been developed with the aim of enhancing lung residence time, thereby reducing the burden of inhaled antimicrobial therapy which requires multiple daily administration due to rapid absorptive clearance of antibiotics from the lungs. However, there is a lack of a predictive methodology available to assess controlled release inhalation delivery systems and their effect on drug disposition. In this study, three ciprofloxacin formulations were evaluated: a liposomal formulation, a solution formulation and a 1:1 combination of the two (mixture formulation). Different methodologies were utilised to study the release profiles of ciprofloxacin from these formulations: (i) membrane diffusion, (ii) air interface Calu-3 cells and (iii) isolated perfused rat lungs. The data from these models were compared to the performance of the formulations in vivo. The solution formulation provided the highest rate of absorptive transport followed by the mixture formulation, with the liposomal formulation providing substantially slower drug release. The rank order of drug release/transport from the different formulations was consistent across the in vitro andex vivo methods, and this was predictive of the profiles in vivo. The use of complimentary in vitro and ex vivo methodologies provided a robust analysis of formulation behaviour, including mechanistic insights, and predicted in vivo pharmacokinetics.     

氨茶碱对支气管哮喘气道重塑大鼠支气管肺组织内皮素-1和一氧化氮含量的影响

目的观察氨茶碱对支气管哮喘气道重塑大鼠气道形态学及肺组织中内皮素-1（ET-1）、一氧化氮（NO）、11型胶原含量的影响。方法24只SD大鼠随机分为正常组、模型组、治疗组,每组8只,除正常组外以卵蛋白致敏并吸入激发法制备大鼠哮喘模型,治疗组、模型组从第1次哮喘激发开始（造模第15天）分别给予氨茶碱35mg·kg^-1·次^-1·d^-1、0．9％氯化钠溶液2ml·次^-1·d^-1灌胃给药,用药4周后处死大鼠,取肺组织HE染色,病理图象分析仪测量支气管壁面积、支气管平滑肌面积,采用放射免疫法测定肺组织ET-1、Ⅲ型胶原含量,采用硝酸还原酶法测定肺组织NO含量。结果与正常组比较,模型组大鼠支气管壁面积、平滑肌面积明显增加（P〈0．01）,肺组织中ET-1、NO、II型胶原含量均明显增加（P〈0．01）;与模型组比较,治疗组大鼠支气管壁面积、平滑肌面积较模型组显著降低（P〈0．01）,肺组织中ET-1、NO、11型胶原含量均显著降低（P〈0．05或〈0．01）结论氨茶碱可通过降低肺组织中ET—1、NO、Ⅲ型胶原含量,抑制哮喘大鼠气道壁、平滑肌增厚,从而抑制支气管哮喘大鼠气道重塑。     

Pharmacokinetics and tissue distribution study of 16-dehydropregnenolone liposome in female mice after intravenous administration

Objective: 16-Dehydropregnenolone (16-DHP) is a potential antitumor compound with poor solubility. A liposome entrapped 16-DHP (16-DHP-LM) formulation was developed to surmount its solubility obstacle. The aim of this study is to investigate the pharmacokinetics of 16-DHP-LM and 16-DHP solution in female mice and tissue distribution of 16-DHP-LM in female tumor-bearing nude mice.

Methods: Rotary-evaporated film method was used to prepare 16-DHP-LM. The comparison of pharmacokinetics between 16-DHP-LM and 16-DHP solution in female mice was investigated after intravenous administration at a single dose of 15?mg/kg. The dose proportionality of 16-DHP-LM was also evaluated after intravenous administration of 16-DHP-LM at the doses of 7.5, 15.0 and 30.0?mg/kg. The tissue distribution of 16-DHP-LM in female tumor-bearing nude mice was evaluated after intravenous administration of 16-DHP-LM at a single dose of 30.0?mg/kg.

Results: The pharmacokinetic study indicated that the 16-DHP-LM group had higher area under the plasma concentration-time curve (AUC), lower apparent volume of distribution (Vz) and smaller systemic clearance (CL) than the 16-DHP solution group. For dose proportionality, good linearity of the pharmacokinetics of 16-DHP after intravenous administration of 16-DHP-LM was observed in the regression analysis of the AUC-dose plot (r?=?0.99) and the C_max-dose plot (r?=?0.98). The tissue distribution study showed that the main tissue depots for 16-DHP in tumor-bearing nude mice were plasma, liver, spleen and tumor, which was benefit to anti-tumor effect. All these results provided a significant basis for the design of clinical trial of 16-DHP-LM.     

酮洛芬及其异丙酯对HaCaT细胞构建的组织工程皮肤的渗透作用

目的体外构建适用于经皮给药研究的组织工程皮肤。方法以表皮角质形成细胞系HaCaT细胞及人真皮成纤维细胞为细胞来源，用I型牛胶原蛋白为真皮基质包埋成纤维细胞，其上接种HaCaT细胞，采用气-液界面方式培养，观察不同的培养介质对组织工程皮肤的影响，HE染色切片观察培养皮肤结构形态。以酮洛芬及其异丙酯为模型药物研究经皮渗透和代谢特性。结果HaCaT细胞经气-液界面培养可形成类表皮层，但不能形成完整的角质层。维生素C可明显促进细胞增殖，维生素D₃可促进细胞分化，雌二醇对此组织工程皮肤没有明显的影响。同皮肤细胞匀浆代谢相似，酮洛芬异丙酯被代谢成原药酮洛芬。结论HaCaT细胞在气-液界面培养条件下可形成多层分化不完全的表皮层，保留了一定的酶活性，可用于药物的经皮渗透和代谢等研究。     

Pharmacokinetics,biodistribution and bioavailability of isoliquiritigenin after intravenous and oral administration

Context: Isoliquiritigenin (ISL) has been shown to exhibit a variety of biological activities. However, there is little research on the pharmacokinetic behavior and tissues distribution of ISL.

Objective: Pharmacokinetics, biodistribution and bioavailability of ISL after intravenous and oral administration were determined by systematic investigation in Sprague–Dawley rats.

Materials and methods: ISL was dissolved in medicinal ethanol-Tween 80–0.9% sodium chloride saline in a volume ratio of 10:15:75. The ISL solution was injected in rats via a tail vein at a single dose of 10, 20 and 50?mg/kg and administered orally in rats at a single dose of 20, 50 and 100?mg/kg, respectively. Blood samples were collected at time intervals of 0.08, 0.25, 0.5, 0.75, 1, 1.5, 2, 3, 6, 8 and 12?h after intravenous injection. Tissues of interests in mice were collected immediately at each determined time point (0.5, 1, 2, 3 and 6?h) after cervical dislocation.

Results: The dose-normalized AUC values were 7.3, 7.6 and 8.7?μg?×?h/ml (calculated based on the dose of 10?mg/kg) for intravenous doses of 10, 20 and 50?mg/kg, respectively. The elimination half-lifes (t_1/2λ) were 4.9, 4.6 and 4.8?h at 10, 20 and 50?mg/kg intravenous doses, respectively. The F values were 29.86, 22.70, 33.62% for oral doses of 20, 50 and 100?mg/kg, respectively. Liver, heart and kidney were major distribution tissues of ISL in mice. The plasma protein binding of ISL in rats was 43.72%.

Conclusion: The work may useful for further study of the bioactive mechanism of ISL.     

The future perspectives of natural materials for pulmonary drug delivery and lung tissue engineering

Introduction: Search for new, functional biomaterials that can be used to synergistically deliver a drug, enhance its adsorption and stimulate the post-injury recovery of tissue function, is one of the priorities in biomedicine. Currently used materials for drug delivery fail to satisfy one or more of these functionalities, thus they have limited potential and new classes of materials are urgently needed.

Areas covered: Natural materials, due to their origin, physical and chemical structure can potentially fulfill these requirements and there is already strong evidence of their usefulness in drug delivery. They are increasingly utilized in various therapeutic applications due to the obvious advantages over synthetic materials. Particularly in pulmonary drug delivery, there have been limitations in the use of synthetic materials such as polymers and lipids, leading to an increase in the use of natural and protein-based materials such as silk, keratin, elastin and collagen. Literature search in each specialized field, namely, silk, keratin and collagen was conducted, and the benefits of each material for future application in pulmonary drug delivery are highlighted.

Expert opinion: The natural materials discussed in this review have been well established in their use for other applications, yet further studies are required in the application of pulmonary drug delivery. The properties exhibited by these natural materials seem positive for their application in lung tissue engineering, which may allow for more extensive testing for validation of pulmonary drug delivery systems.     

Pharmacokinetics,bioavailability and tissue distribution of geniposide following intravenous and peroral administration to rats

In order to characterize the pharmacokinetics, bioavailability and tissue distribution of geniposide following intravenous and peroral administration to rats, a reliable gradient HPLC‐based method has been developed and validated. After p.o. administration of geniposide, the peak concentration of geniposide in plasma occurred at 1 h and plasma geniposide was eliminated nearly completely within 12 h. The AUC_{0→ ∞} values of geniposide were 6.99 ± 1.27 h · µg/ml and 6.76 ± 1.23 h · µg/ml after i.v. administration of 10 mg/kg and p.o. administration of 100 mg/kg of geniposide, respectively. The absolute oral bioavailability (%F) of geniposide was calculated as 9.67%. After p.o. administration of geniposide, the AUC_0→4h values in tissues were in the order of kidney > spleen > liver > heart > lung > brain. This study improved the understanding of the pharmacokinetics, bioavailability and tissue distribution of geniposide in rats and may provide a meaningful basis for clinical application of such a bioactive compound of herbal medicines. Copyright © 2013 John Wiley & Sons, Ltd.     

Pharmacokinetics and penetration of linezolid into inflamed soft tissue in diabetic foot infections

Objective  Physiological changes and local and systemic inflammation may affect plasma and tissue pharmacokinetics of antimicrobial agents in diabetics. The aim of the study was to investigate the penetration of linezolid into inflamed areas of infected diabetic foot wounds and the pharmacokinetics in the risk population of diabetics. Methods  Pharmacokinetics and tissue penetration of linezolid into inflamed diabetic foot infection (DFI) tissue were determined at steady state in 15 patients with diabetes type 2 and DFI following administration of multiple oral doses of 600 mg given every 12 h. Second debridement was performed on days 4–6, 3 h after linezolid administration. Linezolid concentrations were determined in perinecrotic wound tissue of inflamed diabetic foot by high-performance liquid chromatography (HPLC). Results  A mean maximum plasma concentration (C_max) in plasma of 14.3 mg/L was attained at a median of 2.0 h [time to reach C_max (T_max) range 0.5–6.0 h). Area under the concentration time curve from zero to 12 h (AUC_0–12 h) with a mean of 114.1 mg∙h/L and C_min of 5.4 mg/L were achieved in patients with diabetes mellitus type 2. Penetration of linezolid into inflamed areas of DFI with tissue/plasma ratios of mean 101.7% [95% confidence interval (CI) 56; 148%] produced a mean concentration of 9.6 μg/g (95% CI 7.4; 11.8 μg/g) greater than those predicted to be effective against methicillin-resistant staphylococci [minimum concentration that inhibits 90% of organisms (MIC₉₀) of 4 mg/L]. Tissue/plasma ratios correlated positive with systemic inflammation. Conclusion  Plasma pharmacokinetics of linezolid in diabetics and adequate levels in inflamed areas of diabetic foot wound suggest that an oral dose of 600 mg bd of linezolid provides effective concentrations for treating methicillin-resistant Staphylococcus aureus (MRSA) in DFI. Presented in part at the 41th Annual Meeting of the European Association for Study of Diabetes, September 2005 in Athens, Greece, and at the 7th Annual Congress of the German Clinical Pharmacology, November 2005 in Dresden, Germany