ABSTRACT
In this study, we prepared various matrices of hydrogel patches and studied their cross-linking mechanism by observing their rheological properties, which could provide theoretical basis and deep technical support for further industrial development of hydrogel patch. Rheology method was used to do the amplitude scanning and single-frequency scanning for various hydrogel matrix, under the condition of oscillation mode of the rheometer. Then the linear viscoelastic region, composite modulus value, as well as changes in slope with time of the composite modulus and phase angle of various hydrogel matrix were analyzed in detail. The results showed that the stability of matrix was mainly determined by hydrogel frame; only in acidic environment, the cross-linking reaction between cross-linker and hydrogel frame can occur; elasticity of matrix can be decreased by organic acid and the effect level was related to the ratio of the number of carboxyl and hydroxyl (-COO(-)/-OH) in adjusters: if the ratio was not equal, the higher -COO(-)/-OH in adjusters would be the less elasticity of matrix decreased; the cross-linking speed of matrix was determined by adjuster, the cross-linking speed of matrix contain different adjusters was ranged in following order: matrix containing tartaric acid > matrix containing lactic acid > matrix containing malic acid > matrix containing citric acid; the cross-linking speed of matrix was not uniform in the whole cross-linking process.
Subject(s)
Citric Acid , Chemistry , Cross-Linking Reagents , Chemistry , Hydrogels , Chemistry , Lactic Acid , Chemistry , Malates , Chemistry , Rheology , Tartrates , Chemistry , ViscosityABSTRACT
Objective: To evaluate the value of contrast-enhanced magnetic resonance angiography (CE-MRA) in the diagnosis of vertebral stenosis. Methods: A total of 108 patients (216 vertebral arteries) with clinical ischemic symptoms were examined by CE-MRA, then they were examined with digital subtraction angiography (DSA) within one week after CE-MRA examination. Using DSA as a standard, the accuracy of CE-MRA in the diagnosis of vertebral arteries was evaluated. Results: Circled digit oneOf the 216 vertebral arteries, 188 (87.0%) were consistent with the results of CE-MRA and DSA. The stenosis degree of 24 arteries (11.1%) determined by CE-MRA was higher than those determined by DSA. The stenosis degree of 4 arteries (1.9%) determined by CE-MRA was lower than those determined by DSA. Spearman rank correlation coefficient of the 2 kinds of examination was rs = 0.785 (P <0.001). Circled digit twoIn 168 normal vertebral arteries examined by CE-MRA, 2 were mild stenosis (stenosis rate ≤49%) and 2 were moderate to severe stenosis (stenosis rate 50-99%) examined by DSA. Of the 8 arteries with mild stenosis diagnosed by CE-MRA, DSA confirmed that 6 arteries were normal; of the 30 arteries with moderate to severe Stenosis diagnosed by CE-MRA, DSA confirmed that 10 were mild stenosis and 8 were normal. CE-MRA examination showed that the 10 occluded arteries were all confirmed by DSA. Circled digit threeUsing DSA as the gold standard, the sensitivity, specificity, false positive rate, false negative rate, positive predictive value, negative predictive value, and diagnostic consistent of CE-MRA rate were 89.5% (34/38), 92.1% (164/178), 7.9% (14/178), 10.5% (4/38), 70.8% (34/48), 97.6% (164/168), and 91.7% (198/216) , respectively. The Youden index was Y = 0.816. Conclusion: CE-MRA has high sensitivity in the diagnosis of vertebral artery ostial stenosis, it can be used as a screening means for detection. However, if we want to accurately evaluate the stenotic degree of vertebral artery, a variety of examination methods are needed.
ABSTRACT
Objective: To compare the effects of electret and chemical enhancers in enhancing the transdermal delivery of meloxicam. Methods: The study was divided into 4 groups, including meloxicam patch group (control), chemical enhancer + meloxicam patch group, electret meloxicam patch, and electret + chemical enhancer + meloxicam patch group. The in vitro skin permeation of meloxicam from patches was examined by using a modified Franz diffusion cell. Ultraviolet spectrophotometry (362 nm) was used to analyze the drug concentration in the receptor. The 10 h-cumulated permeation amount of meloxicam from patchs was calculated in 3 experimental groups and were compared with that the control group. The enhancing abilities of electret and chemical enhancers were compared and the synergistic effect of them was assessed. Results: (1) 1%, 3% and 5% azones showed 1.20, 1.33, and 1.26 fold-increases in the 10 h-cumulated permeation of meloxiam respectively as compared with control group(P<0.05). (2) Most of the chemical enhancers used in this study(1%, 3% and 5% azones, 10% ethyl oleate, 1% menthnol,and 30% sulphoxiade),except for 20% propylene glycol,had enhancing effect on transdermal delivery of melocicam. Ethyl oleate(10%) was proven to be the most potent enhancer,showing a 1.86-fold cumulated permeation that of the control group(P<0.05); (3) Electret was more potent than the chemical enhancers in promoting meloxicam transdermal delivery, showing a 2.16-fold cumulated permeation that of control group (P<0.05); (4) Electret improved the enhancing effect of chemical enhancers in this study. The cumulated permeation of meloxicam in electret + chemical enhancer + meloxicam patch group was 1.14-2.82 folds that of the chemical enhancer + meloxicam patch group(P<0.05). Conclusion: Electret has a good promoting effect for transdermal drug delivery and can be used as a novel enhancer in transdermal delivery of drugs.