Analytical Methods for Drug Quantification

All APIs (Table 1), SyrSpend^® SF NEO and SyrSpend^® SF PH4 were supplied by Fagron (São Paulo, Brazil). HPLC-grade reagents were procured from Vetec (Rio de Janeiro, Brazil). Ultrapure water, with an 18.2 MΩ cm resistivity at 25 °C and less than 10 ppb total organic carbon, was used throughout the experiments and produced using an AquaMax-Ultra 370 Series system (Young Lin, Anyang, Republic of Korea). The reference standards were acquired directly from the United States Pharmacopeia (USP, Rockville, MD, USA). Immediately before use, all mobile phases were filtered through a 0.45 mm filter membrane (RC-45/15 MS; Chromafil, Düren, Germany) and degassed for 30 min in an ultrasonic water bath (model 1600A; Unique, Indaiatuba, Brazil). All analytical balances and volumetric glassware were calibrated. For indomethacin, UHPLC analyses were performed in a qualified and calibrated Thermo Scientific (Waltham, MA, USA) equipment model Vanquis with software controller Chromeleon 7, version 7.3. HPLC analyses were performed in qualified and calibrated Young Lin equipment with a software controller Clarity version 8.1 (for levodopa/carbidopa, levothyroxine sodium and lomustine) or an Agilent (Santa Clara, CA, USA) equipment model 1260 Infinity with software controller OpenLab CDS version 2.7 (for clozapine, methyldopa and procarbazine).