Identification of impurities in polymyxin B and colistin bulk sample using liquid chromatography coupled to mass spectrometry

The European Pharmacopoeia (Ph. Eur.) describes liquid chromatography-ultraviolet (LC-UV) methods using C(18) stationary phases for the analysis of polymyxin B and colistin. Several unknown impurities were detected in commercial samples of those polypeptide complexes. However, the Ph. Eur. does not specify any related substances for polymyxin B and colistin. Since both methods use non-volatile buffers, the mobile phases were incompatible with mass spectrometry (MS). For the identification of related substances in bulk samples by LC/MS, volatile mobile phase systems were developed. However, the LC/MS methods (with volatile additives) showed inferior chromatographic separation compared to the LC-UV method (with non-volatile additives). Moreover, previously identified impurities by LC/MS could not be assigned in LC-UV methods as the separation in both systems was different. In this study, known impurities were traced in the LC-UV methods and new impurities present in polymyxin B and colistin bulk samples were characterized. To achieve this, each peak from the non-volatile system was collected separately and reinjected into an LC system with a volatile mobile phase coupled to MS. This way, collected impurity peaks were rechromatographed on a reversed phase column in order to separate the analyte from the buffer salts. Using this method, out of 39 peaks, five novel related substances were characterized in a polymyxin B bulk sample. Fourteen impurities, which were already reported in the literature were traced as good as possible in the LC-UV method. In the case of colistin, a total of 36 peaks were investigated, among which four new compounds. Additionally, 30 known impurities were traced in the LC-UV method.

Use of a modified anterior inclined plane in the treatment on the dentoskeletal Class II division 2 patient

Class II malocclusions are seen due to the underdevelopment of the mandible in most of the cases. To compensate for the mandible retrusive position, there is flaring of the lower anterior teeth or retroclination of the central incisors as a compensatory mechanism seen in Class II division 2 type of malocclusion. This case report evaluates the skeletal and dental changes when a 12-year-old female patient with Class II div 2 malocclusion was treated with a modified anterior inclined plane. The postreatment data suggested that there were no significant changes in the vertical skeletal parameters. The upper central incisors were significantly realigned by proclination along with retroclination of the lateral incisors. There was significant increase in the mandibular length. The results revealed that the modified anterior inclined plane showed good results in the treatment of a case of Class II div 2 malocclusion.

Advances and potential applications of chitosan derivatives as mucoadhesive biomaterials in modern drug delivery

Pharmaceutical technologists have been working extensively on various mucoadhesive polymeric systems to create an intimate and prolonged contact at the site of administration. Chitosan is one of the most promising polymers because of its non-toxic, polycationic biocompatible, biodegradable nature, and particularly due to its mucoadhesive and permeation enhancing properties. Due to its potential importance in controlled drug delivery applications, pharmaceutical scientists have exploited this mucoadhesive polymer. However, chitosan suffers from limited solubility at physiological pH and causes presystemic metabolism of drugs in intestinal and gastric fluids in the presence of proteolytic enzymes. These inherent drawbacks of chitosan have been overcome by forming derivatives such as carboxylated, various conjugates, thiolated, and acylated chitosan, thus providing a platform for sustained release formulations at a controlled rate, prolonged residence time, improved patient compliance by reducing dosing frequency, enhanced bioavailability and a significant improvement in therapeutic efficacy. We have explored the potential benefits of these improved chitosan derivatives in modern drug delivery.

Potential prospects of chitosan derivative trimethyl chitosan chloride (TMC) as a polymeric absorption enhancer: synthesis, characterization and applications

In recent years, researchers have been working extensively on various novel properties of polymers to develop increased efficiency of drug delivery and improve bioavailability of various drug molecules, especially macromolecules. Chitosan, a naturally occurring polysaccharide, because of its protonated/polymeric nature, provides effective and safe absorption of peptide and protein drugs. Its transmucosal absorption is, however, limited to acidic media because of its strong intermolecular hydrogen bonds. A new partially quaternized chitosan derivative, N-trimethyl chitosan chloride (TMC), has been synthesized with improved solubility, safety and effectiveness as an absorption enhancer at neutral pH and in aqueous environment. It enhances the absorption, especially of peptide drugs, by reversible opening of tight junctions in between epithelial cells, thereby facilitating the paracellular diffusion of peptide drugs. This derivative thus opens new perspectives as a biomaterial for various pharmaceutical applications/drug delivery systems. This review deals with the potential use of the quaternized chitosan derivative as a permeation enhancer for the mucosal delivery of macromolecular drugs along with its other biomedical applications.

Quality of life after accelerated partial breast irradiation in early breast cancer: matched pair analysis with protracted whole breast radiotherapy

AIMS

To compare the quality of life of women with early breast cancer treated with either accelerated partial breast irradiation (APBI) or whole breast radiotherapy (WBRT).

MATERIALS AND METHODS

After matching for the American Brachytherapy Society criteria, the general European Organization for Research and Treatment of Cancer (EORTC) QLQ-C30 and the breast cancer-specific BR23 modules were given to 48 women (23 APBI and 25 WBRT) who attended the radiotherapy clinic between May 2006 and December 2006 at Tata Memorial Hospital.

RESULTS

The median follow-up of patients in both groups was 3 years. The reliability and validity of the English and translated versions of the questionnaires were tested by Cronbach alpha (0.67-0.96) and Pearson's correlation for scale-scale correlation statistic (0.013-0.505). The scores for social functioning and financial difficulties in QLQ-C30 showed a trend towards a better outcome in the APBI group (P=0.025 and 0.019, respectively) and body image in BR23 was significantly better in the APBI group as compared with the WBRT group (P=0.005). When the analysis was restricted to women receiving chemotherapy in order to eliminate the confounding effect of the heterogeneous use of chemotherapy in the WBRT group, the difference in social functioning was not significant. However, financial difficulties and body image showed a trend towards a worse outcome in the WBRT group.

CONCLUSION

Favourable long-term results of APBI in terms of superior body image perception and lesser financial difficulties compared with WBRT need to be confirmed in larger prospective studies investigating the effect of APBI on quality of life and health economics in different ethnic groups and health care set-ups.

Results of liver resection in combination with radiofrequency ablation for hepatic malignancies

INTRODUCTION

Liver tumors should be surgically treated whenever possible. In the case of bilobar disease or coexisting liver cirrhosis, surgical options are limited. Radiofrequency ablation (RFA) has been successfully used for irresectable liver tumors. The combination of hepatic resection and RFA extends the feasibility of open surgical procedures in patients with liver metastases and hepatocellular carcinoma (HCC).

PATIENTS AND METHODS

RFA was performed with two different monopolar devices using ultrasound guidance. Intraoperative use of RFA for the treatment of liver metastases or HCC was limited to otherwise irresectable tumors during open surgical procedures including hepatic resections. Irresectability was considered if bilobar disease was treated, the functional hepatic reserve was impaired or appraised marginal for allowing further resection.

RESULTS

Ten patients with both liver metastases and HCC, and two patients with cholangiocellular carcinoma were treated. Complete initial tumor clearance was achieved in all patients. Two patients of the metastases group and five patients of the HCC group suffered from local recurrence after a median of 12 months (1-26) (local recurrence rate 32%). Five patients of the metastases group and six patients of the HCC group developed recurrent tumors in different areas of the ablation site after a median time of 4 months (2-18) (distant intrahepatic recurrence in 55%). Survival at 31 months was 36%.

CONCLUSION

RFA extends the scope of surgery in some candidates with intraoperatively found irresectability.

Liquid chromatographic analysis of oxytocin and its related substances

A selective gradient liquid chromatographic (LC) method for the determination of oxytocin (OT) and its related substances in bulk drugs has been developed. The method uses a reversed-phase C18 column (25 cm x 4.0 mm i.d.), 5 microm kept at 40 degrees C. The mobile phases consist of acetonitrile, dihydrogen phosphate solution pH 4.4 and water. The flow rate is 1.0 ml/min. UV detection is performed at 220 nm. A system suitability test (SST) was developed to govern the quality of the separation. The separation towards OT components was investigated on different C18 columns. The developed method was further validated with respect to robustness, precision, sensitivity and linearity. A central composite design was applied to examine the robustness of the method. The method shows good precision, sensitivity, linearity and robustness. Two commercial OT samples were examined using this method. Furthermore, the method proved to be successful when applied to analyze a marketed OT formulation for injection.

Evaluation of caries experience in 3-6-year-old children, and dental attitudes amongst the caregivers in the Ludhiana city

Early Childhood Caries (ECC) is a lifestyle disease that begins when the child's teeth erupt in the oral cavity. The distinctive pattern of decay rapidly spreads from one tooth to another and involves the surfaces of teeth that are usually not at risk. Detection of disease is crucial to control the oral condition using preventive and therapeutic regimes. The aim of this study was to determine the prevalence of caries in children of age 3-6 years in Ludhiana and to examine the relationship between age and caries experience. A total of 609 children in the age group of 3-6 years were examined using def index. To determine dental care seeking attitude, 105 caregivers were interviewed. Results revealed that 52.87% of children in the age group of 3-3.11 years, 45.1% of children in the age group of 4-4.11 years and 58.55% of children in 5-5.11 age groups suffered from caries. The mean def index was 1.82, 1.57 and 2.21, respectively. Interview of caregivers of children revealed that out of 105 only 12 (11.4%) children had previously been to a general dentist. None of them knew about Pedodontics as a specialty. The results of the present study can be used mainly for screening child populations in need of treatment, helping public workers and planners to develop dental health programs to aid early intervention and prevention.

Role of intraventricular sodium nitroprusside in vasospasm secondary to aneurysmal subarachnoid haemorrhage: a 5-year prospective study with review of the literature

OBJECTIVE

Cerebral vasospasm remains an important cause of permanent neurological injury and death following aneurysmal subarachnoid haemorrhage, despite the best current medical therapy. Sodium nitroprusside was recently suggested as a treatment option for cerebral ischaemia in patients with severe medically refractive vasospasm after subarachnoid haemorrhage.

METHODS

Twenty patients of aneurysmal SAH with severe vasospasm, corroborated on transcranial Doppler (TCD), were included in this prospective study. The neurological condition of all patients was classified as Hess and Hunt grade II or higher. The diagnosis of severe delayed cerebral vasospasm refractory to conventional treatment (HHH therapy and nimodipine) was established before treatment. Ten patients received intraventricular sodium nitroprusside (SNP), while the other 10 had either major systemic illness or did not consent, formed the control group of the study. SNP was instilled in escalating doses with a starting dose of 4 mg/mL and reversal of vasospasm was monitored on neurological examination along with TCD in a basic ICU setting without the need for neurophysiological or invasive monitoring.

RESULTS

All patients in the study group showed an improvement in TCD velocities post-SNP instillation. Adverse effects were vomiting and hypotension in the SNP group which responded to medical management. The overall neurological outcome was good or excellent in 7/10 patients in the SNP group. Comparison between the two groups revealed improvement in TCD velocities and GCS in the SNP group thus affecting the long-term prognosis.

CONCLUSION

Intraventricular sodium nitroprusside represents a promising method of treatment for established delayed cerebral vasospasm and cerebral ischaemia refractory to conventional treatment.

Selective cervical nerve root blockade: prospective study of immediate and longer term complications

BACKGROUND AND PURPOSE

Selective cervical nerve root blockade (SCNRB) is a useful procedure for evaluating and treating patients with cervical radiculopathy. Reports of complications related to injections within the cervical nerve root foramen have raised serious doubts regarding the safety of this procedure. This study was performed to prospectively evaluate the safety of fluoroscopically guided outpatient diagnostic and therapeutic SCNRB.

MATERIALS AND METHODS

Eight hundred two consecutive fluoroscopically guided diagnostic and/or therapeutic SCNRBs in 659 patients were performed during a 14-month period (November 2006-December 2007) at affiliated outpatient imaging centers. Each examination was performed by 1 of 8 experienced procedural radiologists by using an anterior oblique approach, with the needle position confirmed with radiographic contrast before injection of an admixture of local anesthetic and steroid. All patients were assessed immediately and at 30 minutes following the procedure. Additionally, 460 patients were called by telephone 30 days following the procedure. All complications were recorded.

RESULTS

Of the 802 attempted procedures, 799 were successfully completed. Three procedures were aborted due to anxiety, challenging body habitus, or persistent venous opacification observed during contrast injection and despite needle repositioning. There were no serious complications, such as stroke, spinal cord insult, permanent nerve root deficit, infection, or significant hematoma. There were 33 minor complications occurring within 30 minutes of the procedure; the most common was vasovagal symptoms. Three hundred forty-five patients were successfully contacted by telephone at 30 days postinjection, 9 of whom reported increased or new pain symptoms.

CONCLUSIONS

With our technique, fluoroscopically guided SCNRB is a safe outpatient procedure with a low immediate and delayed complication rate.

Syndromes associated with labiopalatine clefting: a report of three cases

Clefts of the lip and palate are a common craniofacial anomaly, The etiology is thought to be multifactorial, with both genetic and environmental factors playing a role. Because of the frequent manifestation of cleft lip and palate in association with some syndromes, it is essential that a detailed examination of these patients be carried out. This facilitates early formulation of preventive and treatment advice and aids in overcoming gross deformities in the early stages of development. In this paper, we review three such patients who presented with cleft lip and palate in association with a syndrome.

Simple, sensitive, selective and validated spectrophotometric methods for the estimation of a biomarker trigonelline from polyherbal gels

Simple, accurate, reproducible, selective, sensitive and cost effective UV-spectrophotometric methods were developed and validated for the estimation of trigonelline in bulk and pharmaceutical formulations. Trigonelline was estimated at 265 nm in deionised water and at 264 nm in phosphate buffer (pH 4.5). Beer's law was obeyed in the concentration ranges of 1-20microg mL(-1) (r2=0.9999) in deionised water and 1-24 microg mL(-1) (r2=0.9999) in the phosphate buffer medium. The apparent molar absorptivity and Sandell's sensitivity coefficient were found to be 4.04 x 10(3)L mol(-1)cm(-1) and 0.0422 microg cm(-2)/0.001A in deionised water; and 3.05 x 10(3)L mol(-1)cm(-1) and 0.0567 microg cm(-2)/0.001A in phosphate buffer media, respectively. These methods were tested and validated for various parameters according to ICH guidelines. The detection and quantitation limits were found to be 0.12 and 0.37 microg mL(-1) in deionised water and 0.13 and 0.40 microg mL(-1) in phosphate buffer medium, respectively. The proposed methods were successfully applied for the determination of trigonelline in pharmaceutical formulations (vaginal tablets and bioadhesive vaginal gels). The results demonstrated that the procedure is accurate, precise, specific and reproducible (percent relative standard deviation <2%), while being simple and less time consuming and hence can be suitably applied for the estimation of trigonelline in different dosage forms and dissolution studies.

Validated spectrophotometric methods for the estimation of moxifloxacin in bulk and pharmaceutical formulations

New, simple, cost effective, accurate and reproducible UV-spectrophotometric methods were developed and validated for the estimation of moxifloxacin in bulk and pharmaceutical formulations. Moxifloxacin was estimated at 296 nm in 0.1N hydrochloric acid (pH 1.2) and at 289 nm in phosphate buffer (pH 7.4). Beer's law was obeyed in the concentration range of 1-12 microg ml(-1) (r2=0.9999) in hydrochloric acid and 1-14 microg ml(-1) (r2=0.9998) in the phosphate buffer medium. The apparent molar absorptivity and Sandell's sensitivity coefficient were found to be 4.63 x 10(4) l mol(-1) cm(-1) and 9.5 ng cm(-2)/0.001 A in hydrochloric acid; and 4.08 x 10(4) l mol(-1) cm(-1) and 10.8 ng cm(-2)/0.001 A in phosphate buffer media, respectively indicating the high sensitivity of the proposed methods. These methods were tested and validated for various parameters according to ICH guidelines. The detection and quantitation limits were found to be 0.0402, 0.1217 microg ml(-1) in hydrochloric acid and 0.0384, 0.1163 microg ml(-1) in phosphate buffer medium, respectively. The proposed methods were successfully applied for the determination of moxifloxacin in pharmaceutical formulations (tablets, i.v. infusions, eye drops and polymeric nanoparticles). The results demonstrated that the procedure is accurate, precise and reproducible (relative standard deviation <2%), while being simple, cheap and less time consuming and hence can be suitably applied for the estimation of moxifloxacin in different dosage forms and dissolution studies.