Issue link: https://www.e-digitaleditions.com/i/947832
Tablets & Capsules March 2018 25 dispersion (SDD) places the API molecule in a polymer- mediated solubilized state and maintains that amorphous s t a t e d u r i n g t r a n s i t i o n t h r o u g h t h e p a t i e n t ' s gastrointestinal (GI) tract. You can prepare an SDD quite easily by dissolving both the API and polymer in a suitable solvent that can be readily evaporated (such as acetone or methanol). It's important that the API and polymer both be completely dissolved, otherwise crystalline API may appear in the final SDD. The solution is then delivered into a spray drying unit, which quickly converts the solution into droplets. These droplets dry rapidly in-flight as they travel from the top of the spray dryer to the outlet. The solvent's rapid evaporation traps the API-polymer mixture in the amorphous state and produces a low-density solid particle. The dried SDD material then goes through a post-drying step to ensure complete removal of the solvent. Often, the goal of SDD design is to achieve the ideal in-vivo solubility-enhanced API molecule profile. A crystalline API slowly dissolves but never exceeds its equilibrium solubility limit, as indicated by the light blue line in Figure 2. An SDD's amorphous nature ensures rapid initial API dissolution (referred to as "spring"), as shown by the red line in Figure 2. Following this rapid spring dissolution, the API continues to dissolve over time in the intestinal milieu in a supersaturated state maintained by the presence of the SDD's polymers. An SDD using the same API but a different polymer can achieve the same rapid initial dissolution followed by a sustained high-solubility period (referred to as "parachute"), as shown by the purple line in Figure 2. This spring-and-parachute profile maximizes API exposure and subsequent absorption. While polymer selection for an SDD is dependent on the nature of the API, several well-characterized polymers h a v e b e e n s h o w n t o b e s u c c e s s f u l , i n c l u d i n g hydroxypropyl methylcellulose (HPMC), hydroxypropyl methylcellulose acetate succinate (HPMC-AS), and polyvinylpyrrolidone (PVP). Using biorelevant character- ization dissolution methods, you can determine the API's propensity for precipitation in the GI tract, which will steer your polymer selection and help determine drug loading limitations. Figure 2 Ideal in-vivo pro le of a solubility-enhanced API Spring and parachute Spring Crystalline API Equilibrium solubility limit (C eq ) API concentration Time SAT's, FAT's and IQ/OQ's Global Support and Service Over 130 Years Experience Manufactured in the USA SAT's, FAT's and IQ/OQ's www.rwhartnett.com Contact Us Today! 215-969-9190 info@rwhartnett.com FoUnded 1880 Ink Viscosity and Cleaning Systems Available on All Models! Trusted by Hundreds of Companies in Over 40 Countries Worldwide. Ink Viscosity and See uS at Interphex - Booth 1304 Product Identification and Inspection. Made Simple. Our high-speed printers mark your softgels, capsules, and tablets with pinpoint precision. With vision inspection to ensure accuracy, single tablet rejection, and output rates of up to 500,000 units per hour, identifying your products has never been easier.