RESUMO
Currently, the screening of new drug candidates for intestinal permeation is typically based on in vitro models which give no information regarding regional differences along the gut. When evaluation of intestinal permeability by region is undertaken, two preclinical rat models are commonly used, the Ussing chamber method and single-pass intestinal perfusion (SPIP). To investigate the robustness of in vivo predictions of human intestinal permeability, a set of four model compounds was systematically investigated in both these models, using tissue specimens and segments from the jejunum, ileum, and colon of rats from the same genetic strain. The influence of luminal pH was also determined at two pH levels. Ketoprofen had high and enalaprilat had low effective (Peff) and apparent (Papp) permeability in all three regions and at both pH levels. Metoprolol had high Peff in all regions and at both pHs and high Papp at both pHs and in all regions except the jejunum, where Papp was low. Atenolol had low Peff in all regions and at both pHs, but had high Papp at pH 6.5 and low Papp at pH 7.4. There were good correlations between these rat in situ Peff (SPIP) and human in vivo Peff determined previously for the same compounds by both intestinal perfusion of the jejunum and regional intestinal dosing. The results of this study indicate that both investigated models are suitable for determining the regional permeability of the intestine; however, the SPIP model seems to be the more robust and accurate regional permeability model.
Assuntos
Absorção Fisiológica , Avaliação Pré-Clínica de Medicamentos/métodos , Absorção Intestinal/fisiologia , Modelos Animais , Ratos , Animais , Biofarmácia/métodos , Colo/metabolismo , Concentração de Íons de Hidrogênio , Íleo/metabolismo , Mucosa Intestinal/metabolismo , Jejuno/metabolismo , Masculino , Perfusão/métodos , Permeabilidade , Ratos WistarRESUMO
Over recent decades there has been an increase in the proportion of BCS class II and IV drug candidates in industrial drug development. To overcome the biopharmaceutical challenges associated with the less favorable properties of solubility and/or intestinal permeation of these substances, the development of formulations containing nanosuspensions of the drugs has been suggested. The intestinal absorption of aprepitant from two nanosuspensions (20 µM and 200 µM total concentrations) in phosphate buffer, one nanosuspension (200 µM) in fasted-state simulated intestinal fluid (FaSSIF), and one solution (20 µM) in FaSSIF was investigated in the rat single-pass intestinal perfusion model. The disappearance flux from the lumen (Jdisapp) was faster for formulations containing a total concentration of aprepitant of 200 µM than for those containing 20 µM, but was unaffected by the presence of vesicles. The flux into the systemic circulation (Japp) and, subsequently, the effective diffusion constant (Deff) were calculated using the plasma concentrations. Japp was, like Jdisapp, faster for the formulations containing higher total concentrations of aprepitant, but was also faster for those containing vesicles (ratios of 2 and 1.5). This suggests that aprepitant is retained in the lumen when presented as nanoparticles in the absence of vesicles. In conclusion, increased numbers of nanoparticles and the presence of vesicles increased the rate of transport and availability of aprepitant in plasma. This effect can be attributed to an increased rate of mass transport through the aqueous boundary layer (ABL) adjacent to the gut wall.
Assuntos
Antieméticos/farmacocinética , Absorção Intestinal , Mucosa Intestinal/metabolismo , Morfolinas/farmacocinética , Animais , Antieméticos/química , Aprepitanto , Disponibilidade Biológica , Biofarmácia/métodos , Química Farmacêutica , Masculino , Modelos Animais , Morfolinas/química , Nanopartículas/química , Perfusão/métodos , Ratos , Ratos Wistar , Solubilidade , SuspensõesRESUMO
There is a renewed interest from the pharmaceutical field to develop oral formulations of compounds, such as peptides, oligonucleotides, and polar drugs. However, these often suffer from insufficient absorption across the intestinal mucosal barrier. One approach to circumvent this problem is the use of absorption modifying excipient(s) (AME). This study determined the absorption enhancing effect of four AMEs (sodium dodecyl sulfate, caprate, chitosan, N-acetylcysteine) on five model compounds in a rat jejunal perfusion model. The aim was to correlate the model compound absorption to the blood-to-lumen clearance of the mucosal marker for barrier integrity, 51Cr-EDTA. Sodium dodecyl sulfate and chitosan increased the absorption of the low permeation compounds but had no effect on the high permeation compound, ketoprofen. Caprate and N-acetylcysteine did not affect the absorption of any of the model compounds. The increase in absorption of the model compounds was highly correlated to an increased blood-to-lumen clearance of 51Cr-EDTA, independent of the AME. Thus, 51Cr-EDTA could be used as a general, sensitive, and validated marker molecule for absorption enhancement when developing novel formulations.
Assuntos
Radioisótopos de Cromo/farmacocinética , Ácido Edético/farmacocinética , Excipientes/farmacologia , Absorção Intestinal/efeitos dos fármacos , Mucosa Intestinal/efeitos dos fármacos , Animais , Disponibilidade Biológica , Biofarmácia/métodos , Radioisótopos de Cromo/química , Composição de Medicamentos/métodos , Ácido Edético/química , Mucosa Intestinal/metabolismo , Masculino , Modelos Animais , Perfusão , Permeabilidade/efeitos dos fármacos , Ratos , Ratos Wistar , Dodecilsulfato de SódioRESUMO
CONTEXT: Prediction of the in vivo absorption of poorly soluble drugs may require simultaneous dissolution/permeation experiments. In vivo predictive media have been modified for permeation experiments with Caco-2 cells, but not for excised rat intestinal segments. OBJECTIVE: The present study aimed at improving the setup of dissolution/permeation experiments with excised rat intestinal segments by assessing suitable donor and receiver media. METHODS: The regional compatibility of rat intestine in Ussing chambers with modified Fasted and Fed State Simulated Intestinal Fluids (Fa/FeSSIFmod) as donor media was evaluated via several parameters that reflect the viability of the excised intestinal segments. Receiver media that establish sink conditions were investigated for their foaming potential and toxicity. Dissolution/permeation experiments with the optimized conditions were then tested for two particle sizes of the BCS class II drug aprepitant. RESULTS: Fa/FeSSIFmod were toxic for excised rat ileal sheets but not duodenal sheets, the compatibility with jejunal segments depended on the bile salt concentration. A non-foaming receiver medium containing bovine serum albumin (BSA) and Antifoam B was nontoxic. With these conditions, the permeation of nanosized aprepitant was higher than of the unmilled drug formulations. DISCUSSION: The compatibility of Fa/FeSSIFmod depends on the excised intestinal region. The chosen conditions enable dissolution/permeation experiments with excised rat duodenal segments. The experiments correctly predicted the superior permeation of nanosized over unmilled aprepitant that is observed in vivo. CONCLUSION: The optimized setup uses FaSSIFmod as donor medium, excised rat duodenal sheets as permeation membrane and a receiver medium containing BSA and Antifoam B.
Assuntos
Ácidos e Sais Biliares/química , Células CACO-2/fisiologia , Permeabilidade da Membrana Celular/fisiologia , Intestinos/fisiologia , Jejuno/fisiologia , Solubilidade , Animais , Células CACO-2/química , Humanos , Intestinos/química , Jejuno/química , RatosRESUMO
The development of oral modified-release (MR) dosage forms requires an active pharmaceutical ingredient (API) with a sufficiently high absorption rate in both the small and large intestine. Dogs are commonly used in preclinical evaluation of regional intestinal absorption and in the development of novel MR dosage forms. This study determined regional intestinal effective permeability (Peff) in dogs with the aim to improve regional Peff prediction in humans. Four model drugs, atenolol, enalaprilat, metoprolol, and ketoprofen, were intravenously and regionally dosed twice as a solution into the proximal small intestine (P-SI) and large intestine (LI) of three dogs with intestinal stomas. Based on plasma data from two separate study occasions for each dog, regional Peff values were calculated using a validated intestinal deconvolution method. The determined mean Peff values were 0.62, 0.14, 1.06, and 3.66 × 10(-4) cm/s in the P-SI, and 0.13, 0.02, 1.03, and 2.20 × 10(-4) cm/s in the LI, for atenolol, enalaprilat, metoprolol, and ketoprofen, respectively. The determined P-SI Peff values in dog were highly correlated (R(2) = 0.98) to the historically directly determined human jejunal Peff after a single-pass perfusion. The determined dog P-SI Peff values were also successfully implemented in GI-Sim to predict the risk for overestimation of LI absorption of low permeability drugs. We conclude that the dog intestinal stoma model is a useful preclinical tool for determination of regional intestinal permeability. Still, further studies are recommended to evaluate additional APIs, sources of variability, and formulation types, for more accurate determination of the dog model in the drug development process.
Assuntos
Intestino Grosso/metabolismo , Intestino Delgado/metabolismo , Animais , Atenolol/farmacocinética , Cães , Enalaprilato/farmacocinética , Humanos , Absorção Intestinal , Jejuno/metabolismo , Cetoprofeno/farmacocinética , Masculino , Metoprolol/farmacocinética , PermeabilidadeRESUMO
Currently there are only a limited number of determinations of human Peff in the distal small intestine and none in the large intestine. This has hindered the validation of preclinical models with regard to absorption in the distal parts of the intestinal tract, which can be substantial for BCS class II-IV drugs, and drugs formulated into modified-release (MR) dosage forms. To meet this demand, three model drugs (atenolol, metoprolol, and ketoprofen) were dosed in solution intravenously, and into the jejunum, ileum, and colon of 14 healthy volunteers. The Peff of each model drug was then calculated using a validated deconvolution method. The median Peff of atenolol in the jejunum, ileum, and colon was 0.45, 0.15, and 0.013 × 10(-4) cm/s, respectively. The corresponding values for metoprolol were 1.72, 0.72, and 1.30 × 10(-4) cm/s, and for ketoprofen 8.85, 6.53, and 3.37 × 10(-4) cm/s, respectively. This is the first study where the human Peff of model drugs has been determined in all parts of the human intestinal tract in the same subjects. The jejunal values were similar to directly determined values using intestinal single-pass perfusion, indicating that the deconvolution method is a valid approach for determining regional Peff. The values from this study will be highly useful in the validation of preclinical regional absorption models and in silico tools.
Assuntos
Absorção Intestinal/fisiologia , Mucosa Intestinal/metabolismo , Adolescente , Adulto , Atenolol/metabolismo , Atenolol/farmacocinética , Colo/metabolismo , Feminino , Humanos , Íleo/metabolismo , Intestino Delgado/metabolismo , Jejuno/metabolismo , Cetoprofeno/metabolismo , Cetoprofeno/farmacocinética , Masculino , Metoprolol/metabolismo , Metoprolol/farmacocinética , Pessoa de Meia-Idade , Permeabilidade , Adulto JovemRESUMO
Application of information on regional intestinal permeability has been identified as a key aspect of successful pharmaceutical product development. This study presents the results and evaluation of an approach for the indirect estimation of site-specific in vivo intestinal effective permeability (Peff) in humans. Plasma concentration-time profiles from 15 clinical studies that administered drug solutions to specific intestinal regions were collected and analyzed. The intestinal absorption rate for each drug was acquired by deconvolution, using historical intravenous data as reference, and used with the intestinal surface area and the dose remaining in the lumen to estimate the Peff. Forty-three new Peff values were estimated (15 from the proximal small intestine, 11 from the distal small intestine, and 17 from the large intestine) for 14 active pharmaceutical ingredients representing a wide range of biopharmaceutical properties. A good correlation (r(2) = 0.96, slope = 1.24, intercept = 0.030) was established between these indirect jejunal Peff estimates and jejunal Peff measurements determined directly using the single-pass perfusion double balloon technique. On average, Peff estimates from the distal small intestine and large intestine were 90% and 40%, respectively, of those from the proximal small intestine. These results support the use of the evaluated deconvolution method for indirectly estimating regional intestinal Peff in humans. This study presents the first comprehensive data set of estimated human regional intestinal permeability values for a range of drugs. These biopharmaceutical data can be used to improve the accuracy of gastrointestinal absorption predictions used in drug development decision-making.
Assuntos
Mucosa Intestinal/metabolismo , Budesonida/farmacocinética , Colo/citologia , Ciclosporina/farmacocinética , Fenofibrato/análogos & derivados , Fenofibrato/farmacocinética , Humanos , Absorção Intestinal , Dimesilato de Lisdexanfetamina/farmacocinética , Metoprolol/farmacocinética , Nifedipino/farmacocinética , Pirimidinas/farmacocinética , Ranitidina/farmacocinética , Rivastigmina/farmacocinética , Sumatriptana/farmacocinética , Terfenadina/análogos & derivados , Terfenadina/farmacocinética , Teofilina/farmacocinéticaRESUMO
A multivariate TOF-SIMS methodology has been developed and applied to quantify surface composition and chemical distribution for dry powder blends. Surface properties are often critical to the behavior of powder formulations, especially in the case of dry powders for inhalation, as surface properties directly affect inter-particulate forces and, hence, the dispersibility of the formulation. The mass spectrum at each pixel was fit to a linear combination of reference spectra obtained by non-negatively constrained alternating least squares. From the pixel compositions, average surface coverage and a range of other image features were calculated. Two kinds of systems have been examined: 1) binary blends of lactose particles and coating agents, and 2) blends of different inhalation drugs with carrier lactose. For both kinds of systems, detailed insight into the surface composition and structure could be derived. For the former study, TOF-SIMS results were compared with a complementary surface analysis technique, XPS.
Assuntos
Portadores de Fármacos , Lactose , Administração por Inalação , Aerossóis , Tamanho da Partícula , Pós , Propriedades de SuperfícieRESUMO
Regional in vivo human intestinal effective permeability (Peff ) is calculated by measuring the disappearance rate of substances during intestinal perfusion. Peff is the most relevant parameter in the prediction of rate and extent of drug absorption from all parts of the intestine. Today, human intestinal perfusions are not performed on a routine basis in drug development. Therefore, it would be beneficial to increase the accuracy of the in vitro and in silico tools used to evaluate the intestinal Peff of novel drugs. This review compiles historical Peff data from 273 individual measurements of 80 substances from 61 studies performed in all parts of the human intestinal tract. These substances include: drugs, monosaccharaides, amino acids, dipeptides, vitamins, steroids, bile acids, ions, fatty acids, and water. The review also discusses the determination and prediction of Peff using in vitro and in silico methods such as quantitative structure-activity relationship, Caco-2, Ussing chamber, animal intestinal perfusion, and physiologically based pharmacokinetic (PBPK) modeling. Finally, we briefly outline how to acquire accurate human intestinal Peff data by deconvolution of plasma concentration-time profiles following regional intestinal bolus dosing.