Transdermal Drug Transport and Metabolism. I. Comparison of In Vitro and In Vivo Results

Using excised human skin and tissue grafted to athymic mice, the in vitro and in vivo delivery and metabolism of a salicylate diester were compared. Concentration profiles of this drug and its metabolites were obtained for the outer several hundred microns of the skin. These results show significant differences in the extent of enzymatic cleavage and distribution of metabolites between in vitro and in vivo studies. Furthermore, these data suggest that in vitro results may overestimate metabolism because of increased enzymatic activity and/or decreased capillary removal.     

Inhibition of In Vitro Metabolism of Simvastatin by Itraconazole in Humans and Prediction of In Vivo Drug-Drug Interactions

Purpose. To evaluate an interaction between simvastatin and itraconazole in in vitro studies and to attempt a quantitative prediction of in vivo interaction in humans. Methods. The inhibitory effect of itraconazole on simvastatin metabolism was evaluated using human liver microsomes and the K_i values were calculated for the unbound drug in the reaction mixture. A physiologically-based pharmacokinetic model was used to predict the maximum in vivo drug-drug interaction. Results. Itraconazole competitively inhibited the metabolism of simvastatin to M-1 and M-2 with K_i values in the nM range. The area under the curve (AUC) of simvastatin after concomitant dosing with itraconazole was predicted to increase ca. 84-101-fold compared with that without administration of itraconazole. Taking into consideration the fact that this method predicts the maximum interaction, this agrees well with the clinical observation of a 19-fold increase. A similar prediction, based on the K_i value without taking into account the drug adsorption to microsomes, led to an underevaluation of the interaction. Conclusions. It was demonstrated that the competitive inhibition of CYP3A4-mediated simvastatin metabolism by itraconazole is the main cause of the drug interaction and that a K_i value corrected for drug adsorption to microsomes is the key factor in quantitatively predicting the maximum in vivo drug interactions.     

Study on In Vitro Metabolism and In Vivo Pharmacokinetics of Beauvericin

Beauvericin (BEA) is a well-known mycotoxin produced by many fungi, including Beaveria bassiana. The purpose of this study was to evaluate the in vitro distribution and metabolism characteristics as well as the in vivo pharmacokinetic (PK) profile of BEA. The in vitro metabolism studies of BEA were performed using rat, dog, mouse, monkey and human liver microsomes, cryopreserved hepatocytes and plasma under conditions of linear kinetics to estimate the respective elimination rates. Additionally, LC-UV-MSⁿ (n = 1~2) was used to identify metabolites in human, rat, mouse, dog and monkey liver microsomes. Furthermore, cytochrome P450 (CYP) reaction phenotyping was carried out. Finally, the absolute bioavailability of BEA was evaluated by intravenous and oral administration in rats. BEA was metabolically stable in the liver microsomes and hepatocytes of humans and rats; however, it was a strong inhibitor of midazolam 1′-hydroxylase (CYP3A4) and mephenytoin 4′-hydroxylase (CYP2C19) activities in human liver microsomes. The protein binding fraction values of BEA were >90% and the half-life (T_1/2) values of BEA were approximately 5 h in the plasma of the five species. The absolute bioavailability was calculated to be 29.5%. Altogether, these data indicate that BEA has great potential for further development as a drug candidate. Metabolic studies of different species can provide important reference values for further safety evaluation.     

药品不良反应监测与药品市场监管工作联动机制的探讨

目的:探讨药品不良反应(ADR)监测与药品市场监管工作的关系,以促进2项工作的共同发展。方法:以深圳市ADR监测工作开展情况为例进行分析和探讨。结果与结论:ADR监测与药品市场监管工作是紧密结合在一起的,ADR信息为药品质量监管提供参考依据,并可为药品安全突发事件提供预警;而合理使用药品市场监管手段可提高ADR监测工作的主动性与积极性,并可提高ADR报告评价的准确性。但两者有时也存在一定冲突,需要妥善处理和有效衔接,通过两者协同发展,更好地保证公众用药安全、有效。     

Polysulfone Capillary Fiber for Intraocular Drug Delivery: In Vitro and in Vivo Evaluations

Abstract

Studies were conducted to investigate the usefulness of polysulfone capillary fiber (PCF) as a drug delivery device for intraocular applications. Carboxyfluorescein (CF) was used as a model drug to prepare PCF-dye devices for both in vitro and in vivo kinetic studies. For the in vitro study, PCF-CF devices were incubated in 0.1 M phosphate buffer, pH 7.4 at 37°C, and CF release was quantified at various times up to 5 weeks. In vitro results indicated a bi-phasic, sustained-release profile of CF from the PCF device for over 30 days. PCF-CF devices released 5% and 10% of their initial CF contents by the first and second day following incubation, respectively. By 10 days after incubation, approximately 50% of the dye content was released from the PCF-CF devices. The rate of dye release decreased thereafter, such that 65% and 90% of CF was released by 17 and 28 days after incubation, respectively. In a subsequent study, the in vivo kinetics of the PCF-CF device were determined in the rabbit eye. PCF-dye devices were prepared with the following CF formulations: 1) microsphere-incorporated CF; 2) lyophilized liposome-encapsulated CF; or 3) micronized CF powder. A PCF-dye device was implanted in the vitreous cavity, and fluorophotometry from the retina to the anterior chamber was performed at various times up to 45 days to quantify fluorescein level. At the conclusion of the study, eyes were enucleated and examined for histopathology. The time-course study showed fluorescein level for up to 45 days in the vitreous. The midvitreous concentration-time profile indicated a CF t1/2 of 10 and 30 days for the PCF-CF powder and PCF-CF liposome preparation, respectively. In contrast, the PCF device prepared with microsphere-incorporated CF showed fluorescein level with a t1/2 of less than one week in the vitreous. Histological examination of the eyes implanted with PCF or PCF-dye device showed no sign of ocular toxicity. Collectively, these results indicated that the PCF device is biocompatible and may be useful for the extended release of drugs in the posterior segment of the eye.     

钩吻中非生物碱不同组分体内、外抗肿瘤作用比较研究

目的:探讨钩吻非生物碱不同分离组分的体内、外抗肿瘤作用以及与毒性的关系。方法:采用四甲基偶氮唑盐法分析确定各组分对肿瘤细胞的体外增殖抑制作用,通过对小鼠进行体内急性毒性实验、对H22瘤的抑制作用及对免疫指标的影响实验,综合评价钩吻非生物碱各组分的抗肿瘤作用。结果:钩吻非生物碱成分体外活性高于生物碱成分,钩吻非生物碱组分2对小鼠肝癌H22生长具有明显的抑制作用,胸腺指数明显高于未用药荷瘤组,其它各组分对肿瘤生长无明显影响,毒性大的组分未显示出抗肿瘤作用。结论:钩吻非生物碱具有一定的抗肿瘤作用,对免疫功能有增强作用,其体内、外抗肿瘤作用与毒性无明显相关性。     

脉冲式药物传输系统的体内外评价方法

脉冲式药物传输系统是根据临床治疗的需要。定时将药物释放出来的一种给药系统。本文在文献的基础上，对口服脉冲式药物传输系统的体内外评价方法进行了综述。     

In Vitro and in Vivo Metabolism of the Anti-Cancer Agent CI-1040, a MEK Inhibitor, in Rat, Monkey, and Human

PURPOSE: The use of in vitro and in vivo models using both rodent and non-rodent species plays an important role with regard to metabolism during the drug development process. In this study, we compared the metabolism of a MEK inhibitor (CI-1040) using in vitro and in vivo models with that observed in a cancer patient. METHODS: Radiolabeled CI-1040 was assessed for metabolism using rat and monkey liver microsomes and hepatocytes, as well as in Wistar rats and cynomolgus monkeys via oral administration. Human bile and plasma samples were obtained immediately after administration of CI-1040 to a patient with advanced colon cancer. A combination of HPLC-radiochromatography (HPLC-RAM), LC/MS and LC/MS/MS experiments were used to analyze all resulting metabolites. Unlabeled CI-1040 was administered (100 mg/day, QD) for 15 days to a patient suffering from colon cancer. Bile was collected by the insertion of a T-tube directly into the bile duct over a 14-h period. Metabolites were also monitored in the patient's plasma. RESULTS: Analysis of the metabolites in all species using in vitro and animal models demonstrated that CI-1040 undergoes extensive oxidative metabolism (14 metabolites identified) with subsequent glucuronidation of the hydroxylated metabolites. Metabolites were predominantly excreted through the bile in the animal models. CONCLUSIONS: Overall, the in vitro and animal models in combination provided comprehensive coverage for all metabolites observed in human bile and plasma. In conclusion, the results obtained in this study demonstrate the utility of conducting investigations across species in order to gain complete coverage for successfully predicting human metabolites of new compounds in development.     

辽东葱木皂苷体内外抗肿瘤作用的实验研究

目的通过体内外抗肿瘤实验观察辽东葱木皂苷的抗肿瘤作用.方法:在小鼠异体移植性S180肿瘤模型上观察辽东葱木皂苷的抗肿瘤作用,同时用MTT比色法检测辽东葱木皂苷对腺癌A549和喉癌Hep2细胞株的体外细胞毒作用.结果:辽东葱木皂苷对荷S180小鼠肿瘤生长有明显抑制作用,高、中、低剂量组抑瘤率分别是70.31%,47.23%,41.31%;而且能明显抑制体外培养的肿瘤细胞的生长,对两种细胞有明显的细胞毒效应,其IC50分别是0.0155 mg/ml和0.0246mg/ml;结论:辽东葱木皂苷具有一定的体内外抗肿瘤活性.     

克白颗粒抗白癜风的体内外药效研究

目的 研究克白颗粒抗白癜风的体内外药效,并对克白颗粒进行安全性评价。方法 采用血清药理学实验方法检测克白颗粒含药血清对小鼠黑色素瘤细胞B16f10增殖能力的影响;选取50只健康豚鼠随机分成正常对照组、模型对照组及克白颗粒高、中、低剂量(9.04,4.52,2.26 g·kg^-1·d^-1)组,每组10只,除正常对照组外,其余各组采用化学脱色法连续涂抹7%H₂O₂ 50 d,制备实验性白癜风豚鼠模型,肉眼观察各给药组对实验性白癜风豚鼠模型的疗效,检测豚鼠血液中酪氨酸酶(TRY)、胆碱酯酶(CHE)、单胺氧化酶(MAO)、丙二醛(MDA)的含量;长期毒性实验对克白颗粒进行安全性评价。结果 血清药理学实验表明克白颗粒含药血清能够显著促进B16f10细胞的体外增殖。造模后,模型组豚鼠血清MDA、MAO含量显著升高(P<0.05),CHE、TRY含量显著降低(P<0.05或0.01);与模型对照组比较,克白颗粒高剂量显著降低血清中MDA含量(P<0.01),高、中剂量显著降低MAO的含量(P<0.05)、显著升高CHE的含量(P<0.05),但对TRY含量无显著影响。长期毒性实验结果显示克白颗粒对SD大鼠脏器重量无显著影响。结论 克白颗粒显示出良好的抗白癜风效果,其作用机制可能与调节血液中CHE、MAO、MDA含量、促进黑色素细胞增殖有关。     

Comparison of Calcipotriol with Selected Metabolites and Analogues of Vitamin D3: Effects on Cell Growth Regulation in Vitro and Calcium Metabolism in Vivo

Abstract: Calcipotriol is a novel vitamin D₃ analogue developed for topical treatment of psoriasis. Calcipotriol is believed to act via regulation of cell proliferation and differentiation. In this respect calcipotriol is as potent as 1α,25(OH)₂D₃, the physiologically active form of vitamin D₃, but its calcaemic activity in vivo is 100 to 200 times lower. In the present investigation, the effects of calcipotriol on cell growth regulation in vitro and on calcium metabolism in vivo were compared to those exerted by a number of metabolites and analogues of vitamin D₃. Besides 1α,25(OH)₂D₃, these included the two physiologically occurring metabolites 25(OH)D₃ and 24,25(OH)₂D₃, and the two synthetic analogues 1α(OH)D₃ and 1α,24(OH)₂D₃. 25(OH)D₃ and 24,25(OH)₂D₃ were shown to be inactive both in vitro and in vivo. 1α(OH)D₃ was found to have a low biological activity in vitro, but was highly calcaemic in vivo after biotransformation to 1α,25(OH)₂D₃. Calcipotriol, 1α,24(OH)₂D₃ and 1α,25(OH)₂D₃ were all three potent regulators of cell proliferation and differentiation in vitro. In vivo, only calcipotriol showed a greatly reduced calcaemic activity after both oral and intravenous administration. It is concluded that calcipotriol, with a reduced risk of inducing calcaemic side-effects upon absorption from the skin, possesses a favourable therapeutic profile for topical treatment of hyperproliferative diseases.     

Hydrogels for Site-Specific Drug Delivery to the Colon: In Vitro and in Vivo Degradation

Novel hydrogels based on N,N-dimethylacrylamide, N-t-butylacrylamide, and acrylic acid cross-linked with azoaromatic compounds of varying length and electron density of the azo bond were synthesized. The cross-links are degradable by microbial azoreductases present predominantly in the colon, and the gels appear to be suitable for colon-specific drug delivery. The degradability in vitro and in vivo was found to be related to the degree of swelling of the gels. The higher the degree of swelling, the higher the degradability. However, structural and electronic factors were also shown to influence reduction of azo bonds.     

Inhibition of ATP-Induced Contraction in the Guinea-pig Urinary Bladder in Vitro and in Vivo

Abstract Contractions were elicited by adenosine 5′-triphosphate (ATP) in the guinea-pig urinary bladder in vitro and in vivo. In isolated detrusor strips, tetrodotoxin (3.1 × 10^-6-4.4 × 10^-5M) did not affect contractions induced by a submaximum concentration (10^-3M) of ATP, nor did atropine (1.7 × 10^-6 - 2.1 × 10^-4M), or the anticholinergic agent PR 197 within the concentration range 2.6 × 10^-8 - 2.6 × 10^-5M. In higher concentrations (5.2 × 10^-5-2.6 × 10^-4M), PR 197 inhibited the ATP-response by 60-70% in a way that was not clearly concentration-related. Isoprenaline (10^-7-2.0 × 10^-5M) and noradrenaline (2.5 × 10^-6-10^-4M) reduced the ATP-induced contractions by up to 79%. The effects of the amines were abolished by propranolol (5.2 × 10^-6-3.8 × 10^-5M). Adenosine, 1.0-2.0 × 10^-2M, reduced the ATP-response by about 50%; in lower concentrations, it had no effect. Nifedipine, 7.8 × 10^-7-1.2 × 10^-5M, reduced the responses by 15-795%. Indomethacin (≤2.0 × 10^-4M), and theophylline (2.0 × 10^-4M) had no consistent effects on ATP-induced contractions. Exposure of the preparations to a calcium-free medium reduced and abolished the ATP-response within 60 min. Intravenous injection of ATP (1 -20 mg/kg) caused a rapid and transient increase in intravesical pressure in the anaesthetized guinea-pig. The effect of ATP (3mg/kg) was reduced by atropine(5-10 mg/kg) by approximately 35%. PR 197 (2.5-5 mg/kg) abolished the ATP-response. Isoprenaline (5-100 pg/kg) caused a 53-95% inhibition that could be blocked by propranolol (1 mg/kg). The inhibiting effect of noradrenaline (10-100,μg/kg) could not be blocked by propranolol (1 mg/kg). Adenosine (1.5-3.0 mg/kg) given immediately before ATP completely inhibited the ATP-response. Nifedipine, 0.1-0.2 mg/kg, reduced the ATP-induced contraction by 34 to 100%. It is concluded that the ATP-induced contraction is elicited by a direct effect on the smooth muscle cell. It can be inhibited non-specifically by drugs with different modes of action.     

Kinetic Studies of Dose-Dependent Metabolism of Alprenolol: In Vitro and In Vivo Studies in Different Species

Abstract Kinetic studies of the metabolism of alprenolol were performed with isolated microsomes from the rat, guinea-pig, dog and man at an initial substrate concentration of 0.17-150 μM. In all species the rate of aromatic hydroxylation reached a plateu above 50 μM of alprenolol in contrast to the rate of desisopropylation, where consistent saturation level was not obtained. The Km-values for the aromatic hydroxylation in the guinea-pig and man, 2 ,7 μM and 1.3 μM respectively, showed no concentration dependency in contrast to the rat (Km₁ = 0.20 μM, Km₂ = 26 μM) and the dog (Km₁ = 0.78 μM, Km₂ = 66 μM). The apparent Km-value of 0.20 μM for aromatic hydroxylation in the rat seemed to be of the same order of magnitude as reported spectral dissociation constant (Ks = 0.34 μM). In vivo experiments in the rat by oral administration of 7-700 μmol/kg demonstrated a dose-dependent presystemic elimination of alprenolol. The urinary excretion of hydroxy-alprenolol was significantly lower after the highest dose. It is proposed, that the saturation of the aromatic hydroxylation, catalyzed by a high affinity site or subspecies of cytochrome P-450 with a low capacity. contributes to the dose-dependent kinetics in vivo.     

A Theoretical Basis for a Biopharmaceutic Drug Classification: The Correlation of in Vitro Drug Product Dissolution and in Vivo Bioavailability

A biopharmaceutics drug classification scheme for correlating in vitro drug product dissolution and in vivo bioavailability is proposed based on recognizing that drug dissolution and gastrointestinal permeability are the fundamental parameters controlling rate and extent of drug absorption. This analysis uses a transport model and human permeability results for estimating in vivo drug absorption to illustrate the primary importance of solubility and permeability on drug absorption. The fundamental parameters which define oral drug absorption in humans resulting from this analysis are discussed and used as a basis for this classification scheme. These Biopharmaceutic Drug Classes are defined as: Case 1. High solubility-high permeability drugs, Case 2. Low solubility-high permeability drugs, Case 3. High solubility-low permeability drugs, and Case 4. Low solubility-low permeability drugs. Based on this classification scheme, suggestions are made for setting standards for in vitro drug dissolution testing methodology which will correlate with the in vivo process. This methodology must be based on the physiological and physical chemical properties controlling drug absorption. This analysis points out conditions under which no in vitro-in vivo correlation may be expected e.g. rapidly dissolving low permeability drugs. Furthermore, it is suggested for example that for very rapidly dissolving high solubility drugs, e.g. 85% dissolution in less than 15 minutes, a simple one point dissolution test, is all that may be needed to insure bioavailability. For slowly dissolving drugs a dissolution profile is required with multiple time points in systems which would include low pH, physiological pH, and surfactants and the in vitro conditions should mimic the in vivo processes. This classification scheme provides a basis for establishing in vitro-in vivo correlations and for estimating the absorption of drugs based on the fundamental dissolution and permeability properties of physiologic importance.     

Pharmacokinetics and Metabolism of Transdermal Oxybutynin: In Vitro and in Vivo Performance of a Novel Delivery System

Purpose. The purpose of this work was to characterize in vitro/in vivo delivery and pharmacokinetics of oxybutynin (OXY) and its active metabolite, N-desethyloxybutynin (DEO), by a novel matrix transdermal system (TDS). Methods. Two in vivo, randomized, three-way crossover trials examined single/multiple OXY TDS doses. Abdomen, buttock, and hip application sites were compared and dose proportionality was evaluated. Model independent pharmacokinetics, elimination rate constants, and metabolite/drug ratios were derived from both plasma OXY and DEO concentrations. Results. Single/multiple applications of the OXY TDS to the abdomen yielded mean C _max OXY concentrations of 3.4 ± 1.1/6.6 ± 2.4 ng/mL and median t _max of 36/10 h, with steady state achieved during the second application. Plasma OXY and DEO concentrations decreased gradually after C _max until system removal. Buttock and hip applications resulted in bioequivalent OXY absorption. AUC ratios of DEO/OXY were 1.5 ± 0.4 (single dose) and 1.3 ± 0.3 (multiple dose). Mean in vitro OXY skin absorption (186 g/h) was comparable to the estimated in vivo delivery (163 g/h) over 96 h. Conclusions. Sustained delivery over 4 days and multiple sites allow a convenient, well-tolerated, twice-weekly OXY TDS dosing. A low incidence of anticholinergic side effects is expected during clinical use because of the avoidance of presystemic metabolism and low DEO plasma concentrations. The consistent delivery, absorption, and pharmacokinetics should result in an effective treatment of patients with overactive bladder.     

复方替硝唑栓剂体内外抗阴道毛滴虫研究

目的观察复方替硝唑栓剂的体内外抗阴道毛滴虫作用。方法将临床确诊的滴虫性阴道炎患者100例随机分为两纽，试验纽用复方替硝唑栓治疗，对照组用双唑泰栓治疗，每晚睡前放入阴道1粒。6d为1个疗程，共治疗2个疗程；选用临床分离的阴道毛滴虫9株。观察复方替硝唑栓的体外抗阴道毛滴虫作用。结果临床治愈率复方替硝唑栓为100％，双唑泰栓为78．7％，两者有显著性差异（P〈0．05）；复方替硝唑栓体外抗阴道毛滴虫的抑虫50％浓度（MIC50）、抑虫90％浓度（MIC50）厦最低杀虫浓度（MBC）范围均低于双唑泰栓。结论复方替硝唑检体内外抗阴道毛滴虫作用显著．比双唑泰栓疗效更佳。     

Effects of Antioxidants on Oxygen Toxicity in Vivo and Lipid Peroxidation in Vitro

Abstract: Convulsions and pulmonary damage result when animals are exposed to hyperbaric oxygen at pressures above about 300 kPa. Several hydroxyl radical scavengers (namely dimethylsulphoxide, dimethylthiourea and mannitol), the iron chelator desferoxamine and the lipid antioxidant butylated hydroxytoluene were tested for possible protection against such hyperbaric oxygen toxicity. Dimethylthiourea and dimethylsulphoxide prolonged the latency to the first convulsion, but, surprisingly, dimethylthiourea very significantly increased pulmonary damage at both pressures used (515 and 585 kPa). Desferoxamine also slightly increased lung damage at 585 kPa. Other antioxidants did not alter neurotoxicity or pulmonary toxicity induced by hyperbaric oxygen at 515 or 585 kPa. The antioxidants were also tested for their ability to inhibit lipid peroxidation (TBARS formation) in vitro. Desferoxamine (5 and 50 μM), and butylated hydroxytoluene (0.1 mM and 1 mM) greatly inhibited TBARS formation in brain and lung homogenates incubated at 37°. None of the hydroxyl radical scavengers affected TBARS levels in homogenates. There was no correlation between in vitro inhibition of lipid peroxidation and in vivo protection against oxygen toxicity.