A Survey of Koreans on Sleep Habits and Sleeping Symptoms Relating to Pillow Comfort and Support.

The number of people who complain of sleep disturbances is steadily increasing. An understanding of sleep-related factors is required to address sleep problems. This survey study investigated the sleep habits and sleeping symptoms relating to the comfort and support characteristics of pillows and the relationship between sleep quality and pillow design factors. The study utilized data from 332 participating Korean adults aged 20-76 years (mean age ± SD: males, 40.4 ± 15.2; females, 42.9 ± 15.4). We developed a questionnaire that evaluated sleep habits (sleep duration, bedtime, wake-up time and sleeping position); sleeping symptoms (snoring or coughing, breathing and sleepiness during waking hours) based on the Korean version of the Pittsburgh Sleep Quality Index (PSQI-K) questionnaire; and pillow-related factors (support, comfort, fatigue, height and shape) from existing pillow studies. The average sleep duration was 6.8 h, with more than half (52%) of participants sleeping in the supine position. The overall score for sleep quality was considered poor (4.84 points on a seven-point Likert scale), with some degree of sleepiness during waking hours (4.4 points on a seven-point Likert scale). Females went to bed earlier than males and were more likely to sleep in the lateral position compared to males. The number of toss and turn or waking events during sleep increased with age, and older individuals went to sleep earlier and woke up earlier. Among the symptoms of fatigue, pain, discomfort with changing position, snoring, coughing and breathing discomfort, participants reported their highest levels of discomfort due to sleepiness after waking, and they experienced the least head pain. Participants who used a regular-type pillow had poorer satisfaction on multiple comfort and support factors (support, comfort, height suitability, shape suitability) compared with those who used a functional-type pillow. Less head fatigue, less neck fatigue and less shoulder pain had significant effects on sleep quality. To reduce neck fatigue and shoulder pain, designers should consider the height for neck support in the lateral position. To reduce neck fatigue, it is desirable to use materials like latex or memory foam that provide neck support, which can improve sleep quality. The findings of this study contribute to a better understanding of sleep habits and characteristics of pillow comfort and provide practical guidelines for better pillow designs.

Effect of solvent type on the nanoparticle formation of atorvastatin calcium by the supercritical antisolvent process.

The aims of this study were to identify how the solvent selection affects particle formation and to examine the effect of the initial drug solution concentration on mean particle size and particle size distribution in the supercritical antisolvent (SAS) process. Amorphous atorvastatin calcium was precipitated from seven different solvents using the SAS process. Particles with mean particle size ranging between 62.6 and 1493.7 nm were obtained by varying organic solvent type and solution concentration. By changing the solvent, we observed large variations in particle size and particle size distribution, accompanied by different particle morphologies. Particles obtained from acetone and tetrahydrofuran (THF) were compact and spherical fine particles, whereas those from N-methylpyrrolidone (NMP) and dimethylsulfoxide (DMSO) were agglomerated, with rough surfaces and relatively larger particle sizes. Interestingly, the mean particle size of atorvastatin calcium increased with an increase in the boiling point of the organic solvent used. Thus, for atorvastatin particle formation via the SAS process, particle size was determined mainly by evaporation of the organic solvent into the antisolvent phase. In addition, the mean particle size was increased with increasing drug solution concentration. In this study, from the aspects of particle size and solvent toxicity, acetone was the better organic solvent for controlling nanoparticle formation of atorvastatin calcium.

Preparation, characterization and in vivo evaluation of amorphous atorvastatin calcium nanoparticles using supercritical antisolvent (SAS) process.

In this work, amorphous atorvastatin calcium nanoparticles were successfully prepared using the supercritical antisolvent (SAS) process. The effect of process variables on particle size and distribution of atorvastatin calcium during particle formation was investigated. Solid state characterization, solubility, intrinsic dissolution, powder dissolution studies and pharmacokinetic study in rats were performed. Spherical particles with mean particle size ranging between 152 and 863 nm were obtained by varying process parameters such as precipitation vessel pressure and temperature, drug solution concentration and feed rate ratio of CO2/drug solution. XRD, TGA, FT-IR, FT-Raman, NMR and HPLC analysis indicated that atorvastatin calcium existed as anhydrous amorphous form and no degradation occurred after SAS process. When compared with crystalline form (unprocessed drug), amorphous atorvastatin calcium nanoparticles were of better performance in solubility and intrinsic dissolution rate, resulting in higher solubility and faster dissolution rate. In addition, intrinsic dissolution rate showed a good correlation with the solubility. The dissolution rates of amorphous atorvastatin calcium nanoparticles were highly increased in comparison with unprocessed drug by the enhancement of intrinsic dissolution rate and the reduction of particle size resulting in an increased specific surface area. The absorption of atorvastatin calcium after oral administration of amorphous atorvastatin calcium nanoparticles to rats was markedly increased.