Prediction of in vivo supersaturation and precipitation of poorly water-soluble drugs: Achievements and aspirations

Pediatric Formulation Optimization Using a Rational Design: Exploring Amorphous Solid Dispersion Technology with Terbinafine Hydrochloride as a Case Study

Developing orally administered pediatric formulations presents significant challenges due to the unique characteristics of pediatric patients. Terbinafine hydrochloride (TER), a powerful antifungal agent, is effective against various fungal infections, including Tinea capitis, which is common in children. However, its low aqueous solubility necessitates innovative pharmaceutical strategies to enhance its effectiveness. This study describes a rational approach to selecting suitable carriers, approved for use in children, to increase the apparent solubility of TER and to guide the development of amorphous solid dispersions containing this drug. Assessments of solubility parameters, equilibrium solubility measurements, and calculations of pediatric dose numbers guided formulation development using theoretical and experimental methodologies. Carriers like Plasdone S-360 ULTRA®, HPMCAS L, and Soluplus® demonstrated favorable solubility parameter values with TER, indicating potential for drug solubilization. The solubility of TER was strongly dependent on pH. In buffer pH 6.5 containing 10% (w/v) of Soluplus®, TER presented the highest solubility value. The solid-state characterization techniques employed to assess the precipitate formed after equilibrium solubility studies during preformulation demonstrated that there were no phase transitions and no significant interactions between the drug and the evaluated carriers. Furthermore, the results demonstrate that Soluplus® achieved the lowest dose number (0.23) for pediatric patients over 6 years old. So, it was selected for preparing the amorphous solid dispersion via spray drying, which significantly enhanced the apparent solubility of TER while maintaining prolonged supersaturation, offering a promising alternative for developing solid formulations of this drug, particularly for pediatric patients, as it aims to improve oral bioavailability.

Integrating Dynamic in vitro Systems and Mechanistic Absorption Modeling: Case Study of Pralsetinib

Dynamic in vitro absorption systems and mechanistic absorption modeling via PBPK have both shown promise in predicting human oral absorption, although these efforts have been largely separate; this work aimed to integrate knowledge from these approaches to investigate the oral absorption of a RET inhibitor, pralsetinib, with BCS Class II properties. Tiny-TIM (TIM B.V., Weteringbrug​, The Netherlands) is a dynamic in vitro model with close simulation of the successive physiological conditions of the human stomach and small intestine. Tiny-TIM runs with pralsetinib were performed at doses of 200 mg and 400 mg under fasting conditions. Mechanistic modeling of absorption was performed in Simcyp V21 (Certara, Manchester, UK). Pralsetinib fasted bioaccessibility in the Tiny-TIM system was 63% at 200 mg and 53% at 400 mg; a 16% reduction at 400 mg was observed under elevated gastric pH. Maximum pralsetinib solubility from the small intestinal compartment in Tiny-TIM directly informed the supersaturation/precipitation model parameters. The PBPK model predicted a similar fraction absorbed at 200 mg and 400 mg, consistent with the dose proportional increases in observed pralsetinib exposure. Integrating dynamic in vitro systems with mechanistic absorption modeling provides a promising approach for understanding and predicting human absorption with challenging low solubility compounds.

Using Tiny-TIM Dissolution and In Silico Simulation to Accelerate Oral Product Development of a BCS Class II Compound

Though oral drug delivery is the most preferred route of administration, there is high drug pharmacokinetic variability associated with the oral route. Change in drug substance particle size distribution, formulation composition, or manufacturing process may impact the dissolution and, hence, the systemic drug absorption in biopharmaceutics classification system class II compounds. In the present research, using a Boehringer Ingelheim investigational drug substance as the model compound, the tiny-TIM in vitro data and in silico pharmacokinetic model were used to establish in vitro-in vivo correlation and to predict the oral bioavailability. The level C in vitro-in vivo correlation between in vivo AUC and in vitro amount dissolved in both fasted and fed states could be established. Furthermore, level A in vitro-in vivo correlation was established between in vivo fraction absorbed and bioaccessibility from tiny-TIM dissolution in both fasted and fed states. Prediction of positive food effect from tiny-TIM dissolution was consistent with conclusion from clinical studies. Such predictive models developed using the minimum clinical data and the in vitro tiny-TIM data have the potential to reduce the animal and human experiments and to expedite the overall drug development process.