Solid–Liquid Equilibrium in Co-Amorphous Systems: Experiment and Prediction

In this work, the solid–liquid equilibrium (SLE) of four binary systems combining two active pharmaceutical ingredients (APIs) capable of forming co-amorphous systems (CAMs) was investigated. The binary systems studied were naproxen-indomethacin, naproxen-ibuprofen, naproxen-probucol, and indomethacin-paracetamol. The SLE was experimentally determined by differential scanning calorimetry. The thermograms obtained revealed that all binary mixtures investigated form eutectic systems. Melting of the initial binary crystalline mixtures and subsequent quenching lead to the formation of CAM for all binary systems and most of the compositions studied. The experimentally obtained liquidus and eutectic temperatures were compared to theoretical predictions using the perturbed-chain statistical associating fluid theory (PC-SAFT) equation of state and conductor-like screening model for real solvents (COSMO-RS), as implemented in the Amsterdam Modeling Suite (COSMO-RS-AMS). On the basis of the obtained results, the ability of these models to predict the phase diagrams for the investigated API–API binary systems was evaluated. Furthermore, the glass transition temperature (Tg) of naproxen (NAP), a compound with a high tendency to recrystallize, whose literature values are considerably scattered, was newly determined by measuring and modeling the Tg values of binary mixtures in which amorphous NAP was stabilized. Based on this analysis, erroneous literature values were identified.

Cabozantinib in the treatment of metastatic renal cell carcinoma - final data analysis from four oncology centers in the Czech Republic

BACKGROUND

Current standard treatments for patients with metastatic renal cell carcinoma (mRCC) involve tyrosine kinase inhibitors (TKI) that inhibit angiogenesis. Cabozantinib is a multi TKI used for the treatment of mRCC in the first- and second-line setting.

PURPOSE

The aim of this study was the final analysis of treatment outcomes in patients with metastatic renal cell carcinoma (mRCC) treated with cabozantinib after previous targeted therapy.

PATIENTS AND METHODS

A total of 54 patients with mRCC from four oncology centers in the Czech Republic were evaluated retrospectively; the median follow-up was 18.5 months. Cabozantinib was administered in a dose of 60mg/day, a subset of patients received an initial dose of 40mg/day. The treatment was administered until the progression. The Kaplan-Meier analysis was used to calculate progression free survival (PFS) and overall survival (OS). We performed a multivariate analysis of risk factors for treatment outcomes (PFS, OS) by regression analysis. All statistics were evaluated at the significance level α = 0.05.

RESULTS

The median PFS in all patients was 9.3 months (95% CI 7.2 - 11.4). The median OS in all patients was 21.9 months (95% CI 15.5 - 28.4). The median PFS in patients with bone metastases was not statistically significantly different compared with patients without bone metastases (9.3 vs 8.7 months, P = 0.53). The median OS in patients with bone metastases was statistically significantly shorter compared with patients without bone metastases (17.7 vs 26.8 months, P = 0.021). A treatment response was observed in 40.7 % of cases, including one complete remission. The regression analysis demonstrated a significant effect on OS in patients with the presence of subsequent treatment (P = 0.001), patients with treatment duration of first line therapy 6 months (P = 0.019) and 12 months (P = 0.003) and in patients without bone metastases (P = 0.021).

CONCLUSION

Our final analysis of patients with mRCC treated with cabozantinib after previous targeted therapy confirmed its effectiveness.

Effect of a low salt diet on blood pressure and vasoactive hormones in the hereditary hypertriglyceridemic rat

In hereditary HTG rats, basal systolic blood pressure using tail-cuff sphygmomanometry was significantly higher (122.1 +/- 2.1 mm Hg; n = 16) than that in NTG animals (107.1 +/- 1.52; n = 16). A low salt diet did not influence blood pressure in NTG rats during the consecutive 4 weekly periods. However, in the second week blood pressure in HTG rats rose significantly in both the control rats on a normal salt diet and those on a low salt diet (132.5 +/- 1.89, n = 8, and 132.6 +/- 1.93, n = 8). No further changes were registered in the third and fourth week in control HTG rats. On the other hand, blood pressure fell significantly in HTG rats on a low salt diet in the third week in comparison with the second week (119.5 +/- 3.2, n = 8), and it increased again in the fourth week (123.0 +/- 2.35, n = 8). Hormones in plasma were determined at the end of the experiment. Plasma levels of norepinephrine were not influenced by differences in salt intake and were significantly higher by about 45% in HTG than in NTG animals. The lowest concentration of corticosterone in plasma was found in control HTG rats (1.2 +/- 0.2 vs 4.6 +/- 0.8 micrograms/100 ml in control NTG rats). Nevertheless, corticosterone concentration increased in HTG rats on a low salt diet at comparable values found in NTG rats on a low salt diet (3.1 +/- 0.8 vs 4.3 +/- 1.5). Plasma renin activity and plasma aldosterone concentrations were not different in the NTG and HTG groups and were uninfluenced by the diets (Table 1). We conclude that the elevated blood pressure in HTG rats and its variations during the experiment may reflect more pronounced sympathetic activity in HTG rats rather than blood pressure dependency on different salt intake.

On the role of digoxin-like substances, ANP, and AVP in natriuresis induced by hypertonic saline infusion in dogs

The increase of sodium concentration in cerebrospinal fluid or in plasma triggers the osmoregulatory mechanism, namely, the enhancement of renal free-water reabsorption and natriuresis. The increase of free-water reabsorption has been recognized for many years as a consequence of the osmotically released vasopressin (AVP). However, the control of renal sodium excretion in the mechanism of osmoregulation has not been clarified It has been suggested to be, at least in part, of hormonal nature, implying the decreased release of aldosterone and the increased release of atrial natriuretic peptide (ANP), digoxin-like substances (DLIS), and AVP. Neither of these factors, however, has been unequivocally linked to the mechanism of immediate natriuresis caused by an acute increase in cerebrospinal fluid or plasma sodium concentration. It was reconfirmed in our present experiments in anesthetized dogs that aldosterone, ANP, and DLIS could hardly play a role in the immediate natriuresis after the i.v. infusion of hypertonic saline (20% NaCl solution infused in 20 min in an amount that was 0.13% of body weight). However, the role of AVP in this type of natriuresis seems more promising as a V1/V2 receptor antagonist applied i.v. before the hypertonic saline loading completely prevented the increase of renal sodium excretion. Natriuresis after the isotonic saline load was not impaired by the same antagonist of vasopressin receptors.