A quantitative model for metabolic intervention using gut microbes

Model-Informed drug development of gastroretentive release systems for sildenafil citrate

Gastroretentive drug delivery systems (GRDDS) are modified-release dosage forms designed to prolong their residence time in the upper gastrointestinal tract, where some drugs are preferentially absorbed, and increase the drug bioavailability. This work aimed the development of a novel GRDDS containing 60 mg of sildenafil citrate, and the evaluation of the feasibility of the proposed formulation for use in the treatment of pulmonary arterial hypertension (PAH), for once a day administration, by using in silico pharmacokinetic (PK) modeling and simulations using GastroPlus^TM. The Model-Informed Drug Development (MIDD) approach was used in formulation design and pharmacokinetic exposure prospecting. A 2² factorial design with a central point was used for optimization of the formulation, which was produced by direct compression and characterized by some tests, including buoyancy test, assay, impurities, and in vitro dissolution. A compartmental PK model was built using the GatroPlus^TM software for virtual bioequivalence of the proposed formulations in comparison with the defined target release profile provided by an immediate release (IR) tablet formulation containing 20 mg of sildenafil administered three times a day (TID). The results of the factorial design showed a direct correlation between the dissolution rate and the amount of hydroxypropyl methyl cellulose (HPMC) in the formulations. By comparing the PK parameters predicted by the virtual bioequivalence, the formulations F1, F2, F3 and F5 failed on bioequivalence. The F4 showed bioequivalence to the reference and was considered the viable formulation to substitute the IR. Thus, GRDDS could be a promising alternative for controlling the release of drugs with a pH-dependent solubility and narrow absorption window, specifically in the gastric environment, and an interesting way to reduce dose frequency and increase the drug bioavailability. The MIDD approach increases the level of information about the pharmaceutical product and guide the drug development for more assertive ways.

A Silk-Based Platform to Stabilize Phenylalanine Ammonia-lyase for Orally Administered Enzyme Replacement Therapy

Phenylalanine ammonia-lyase (PAL) has gained attention in recent years for the treatment of phenylketonuria (PKU), a genetic disorder that affects ∼1 in 15 000 individuals globally. However, the enzyme is easily degraded by proteases, unstable at room temperature, and currently administered in PKU patients as daily subcutaneous injections. We report here the stabilization of the PAL from Anabaena variabilis, which is currently used to formulate pegvaliase, through incorporation in a silk fibroin matrix. The combination with silk stabilizes PAL at 37 °C. In addition, in vitro studies showed that inclusion in a silk matrix preserves the biological activity of the enzyme in simulated intestinal fluid, which will enable oral administration of PAL to treat PKU.

Pharmacokinetic Study of Four Major Bioactive Components of Liandan Xiaoyan Formula in Ulcerative Colitis and Control Rats Using UPLC-MS/MS

Liandan Xiaoyan Formula (LXF), a classic Traditional Chinese medicine (TCM) formula, is composed of two Chinese herbal medicines for treating bowel disease under the TCM theory. This study aimed to develop a rapid, stable, sensitive, and reliable method based on ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) to simultaneously determine four major bioactive components of LXF (andrographolide, dehydroandrographolide, 1-methoxicabony-β-carboline, 4-methoxy-5-hydroxy-canthin-6-one) in rat serum and evaluate the pharmacokinetic characteristics of LXF in ulcerative colitis (UC) and control rats. After pretreating by protein precipitation with methanol, separation was performed on a UPLC C18 column using gradient elution with a mobile phase consisting of acetonitrile and 0.1% formic acid at a flowing rate of 0.4 ml/min. Detection was performed on Triple-TOF™ 5600 mass spectrometry set at the positive ionization and multiple reaction monitoring (MRM) mode. The validated method showed good linearity (R² ≥ 0.9970), the intra- and inter-day accuracy were within ±11.58%, whereas the intra- and inter-day precision were less than 13.79%. This method was validated and applied to compare the pharmacokinetic profiles of the analytes in serum of UC induced by dextran sulphate sodium (DSS) and control rats after oral administration of LXF. The results showed that four major bioactive components of LXF were quickly absorbed after oral administration in both groups, with higher exposure levels in the UC group. This relationship between the active ingredients’ pharmacokinetic properties provided essential scientific information for applying LXF in clinical.