Fluid bed granulation of a poorly water soluble, low density, micronized drug: comparison with high shear granulation

A 2(4-1) fractional factorial design was used to evaluate the effect of various process variables in fluid bed granulation, on the physico-chemical properties of granule and tablet containing a high dose, poorly water soluble, low density, and micronized drug. The process variables studied were inlet air temperature, inlet air flow, spray rate of the binder solution, and atomization air pressure. Tablets with identical composition, weight, size and hardness were also manufactured in a high shear granulator and their physical properties were determined and compared with those produced by the fluidized bed granulation method. Except for the granule size distribution, other physical properties of granulations and tablets produced in a fluid bed granulator are independent of the selected process variables within the study range. Both atomization air pressure and spray rate of the binder solution had strong impact on granule size distribution. Irrespective of the process conditions used in the fluid bed granulation, granules from this process were more porous, less dense and more compressible than the granules from the high shear granulation process. Comparable tablet dissolution rates to those prepared by the optimized high shear granulation method can be achieved by selecting the appropriate process conditions in fluid bed granulation. These results suggest that wet granulation tablets of a high dose, poorly water soluble, low density, micronized drug can be manufactured using a fluidized bed granulation method, with comparable tablet dissolution rates to those produced with an optimized high shear granulation method.

Effect of oestrogen replacement therapy on bone mass in post-menopausal Bangladeshi women

The female population comprises 48.66% of our total population, of which 10.30% are above the age of 49, many of whom are post-menopausal. Menopause is associated with bone-loss and its consequences. Hormone replacement therapy (HRT), particularly replacement of estrogen, prevents bone-loss. We undertook this prospective case-controlled study to find out whether or not HRT is beneficial to our women. A total of 106 patients were studied, amongst them 60 were cases and 46 were controls. The women in the first group were given either conjugated equine estrogen alone (surgical menopause group) or conjugated equine estrogen plus cyclical progesterone (natural menopause group). Results showed that there was 4.29% increase in bone mineral density in women who received hormone replacement therapy (HRT). This increase was 5.23% in early and 3.56% in late menopause group. Women with natural menopause gained more bone mass (4.22%) than women with surgical menopause (3.9%). Our results also showed that women who denied HRT (controls) lost bone mass (5.26%), the loss was more in those with surgical menopause (6.24%) than those with natural menopause (4.87%). Therefore it can be concluded that post-menopausal hormone replacement therapy prevents bone-loss. However, to evaluate the beneficial effect of long-term HRT, further studies with larger samples are recommended.

Resistance to nonspecific protein adsorption by poly(vinyl alcohol) thin films adsorbed to a poly(styrene) support matrix studied using surface plasmon resonance

Thin films of poly(vinyl alcohol) (PVA) polymer were prepared on a flat, nonporous, poly(styrene) support matrix by adsorption from aqueous solution and were characterized in order to investigate the nonspecific adsorption of proteins to a chromatographically relevant surface. The integrity and surface coverage of the PVA thin films were established by surface analysis and atomic force microscopy imaging. The adsorption of the PVA polymers to the poly(styrene) substrate and the nonspecific adsorption of proteins to the PVA-coated surface were monitored using surface plasmon resonance. PVA was strongly bound to the poly(styrene) surface, but the surface density of the adsorbed PVA polymers was affected substantially by the concentration, molecular weight, and degree of hydrolysis of PVA polymers used. There was evidence of increasing degrees of unfolding of the PVA polymer onto the poly(styrene) surface as the concentration of the the PVA coating solution increased. Complete PVA coverage of the poly(styrene) surface was observed at PVA concentrations of 0.1 mg/mL or greater but with significant influence of both molecular weight and degree of hydrolysis of the PVA polymers. Resistance of the PVA-coated poly(styrene) surface to the nonspecific adsorption of human serum albumin (HSA) correlated with the degree of surface coverage of the PVA. The use of anti-HSA as a probe for adsorbed HSA suggested that HSA was displacing PVA from the poly(styrene) surface at the lower PVA surface coverage. A complete barrier to nonspecific protein adsorption was observed with a PVA coating solution concentration of greater than 0.1 mg/ mL with a degree of hydrolysis of <88%.

Calcium pyrophosphatase dihydrate (CPPD) crystal deposition disease in a teaching hospital in Kuwait

OBJECTIVE

A Medline electronic search showed a paucity of reports on calcium pyrophosphate dihydrate crystal deposition disease (CPPD-CDD) from the Gulf region. To date only a single case report has been published from this region. Therefore, this study aimed, firstly, at finding out the prevalence of chondrocalcinosis in adult Arabs in Kuwait presenting with knee arthritis and, secondly, at carrying out an observational study of CPPD-CDD among Arabs in Kuwait.

METHODS

For the study of the prevalence of chondrocalcinosis 100 consecutive adult patients presenting with knee arthritis were radiologically examined. For the observational study the clinical, laboratory, and radiological findings were analysed in patients with CPPD-CDD seen over a period of five years.

RESULTS

This study showed the presence of chondrocalcinosis in two (2%) of the 100 adult Kuwaiti and other Middle-Eastern Arab patients (70 men, 30 women, median age 50 (range 45-80)) who presented to the rheumatology clinic for the evaluation of knee pain. When the younger age of the group (only three patients aged >70) is taken into account the figure was comparable with that reported from Western countries. Over a period of five years a total of 2726 new patients were evaluated at the rheumatology clinic of this institution. A diagnosis of crystal arthritis was made in 85 patients (3%). Fourteen of these 85 (that is, 16.5%, but 0.5% of the total cases) were diagnosed with definite (eight patients) or probable (six patients) CPPD-CDD. Different clinical presentations, including that of acute monarthritis (that is, pseudogout), premature generalised osteoarthritis, and polyarticular rheumatoid-like presentations, were seen in different patients. Overlap with true gout, with the additional presence of monosodium urate crystals in the joint aspirate, was seen in two patients.

CONCLUSION

The present report shows that CPPD-CDD may not be uncommon among Arabs in the Gulf region. A high degree of clinical awareness and routine examination of joint aspirates with careful analysis for crystals may make it a more common diagnosis in this part of the world. In this regard it is interesting to note that cases and case series including familial cases have been reported from North Africa, especially Tunisia, indicating that the disease has been well described in Arabs of other geographical regions.

Glucagon stimulates expression of the inducible cAMP early repressor and suppresses insulin gene expression in pancreatic beta-cells

The hormone glucagon is secreted by the alpha-cells of the endocrine pancreas (islets of Langerhans) during fasting and is essential for the maintenance of blood glucose levels by stimulation of hepatic glucose output. Excessive production and secretion of glucagon by the alpha-cells of the islets is a common accompaniment to diabetes. The resulting hyperglucagonemia stimulates hepatic glucose production, thereby contributing to hyperglycemia of diabetes. The reduced insulin secretion in diabetes and resultant failure to suppress glucagon secretion by intra-islet paracrine mechanisms is believed to cause the hypersecretion of glucagon. Here, we report the discovery of a new mechanism by which glucagon suppresses insulin secretion. We show that glucagon, but not glucagon-like peptide 1 (GLP-1), or pituitary adenylyl cyclase-activating peptide (PACAP) specifically induces the expression of the transcriptional repressor inducible cAMP early repressor (ICER) in pancreatic beta-cells, resulting in a repression of the transcriptional expression of the insulin gene. Remarkably, glucagon, GLP-1, and PACAP all stimulate the formation of cAMP to a comparable extent in rat pancreatic islets, but only glucagon activates the expression of ICER and represses insulin gene transcription in beta-cells. These findings lead us to propose that hyperglucagonemia may additionally aggravate the diabetic phenotype via a suppression of insulin gene expression mediated by the transcriptional repressor ICER.

Glucagon-like peptide 1 increases glucose-dependent activity of the homeoprotein IDX-1 transactivating domain in pancreatic beta-cells

Both glucose and glucagon-like peptide 1 (GLP-1) stimulate insulin gene transcription in endocrine pancreatic beta-cells within the islets of Langerhans. The effects of glucose are mediated by the homeodomain transcription factor islet duodenum homeobox -1 (IDX-1) that binds to two adenine thymidine-rich (A1 and A2/3) motifs within the rat insulin promoter. Glucose stimulates the activity of the transactivation domain of IDX-1 that lies within the first 80 amino acids of the IDX-1 protein. The effects of GLP-1 on insulin gene expression are primarily conferred by the cAMP responsive element (CRE) within the insulin promoter. GLP-1 stimulates glucose-dependent insulin release from beta-cells. We hypothesize that GLP-1 may augment the effects of glucose on insulin gene transcription. Here we show that GLP-1 stimulates insulin gene transcription independent of the CRE and is glucose-dependent. Furthermore, we show that GLP-1 stimulates the transactivational activity of IDX-1.

Glucagon-like peptide 1 stimulates insulin gene promoter activity by protein kinase A-independent activation of the rat insulin I gene cAMP response element

Glucagon-like peptide 1 (GLP-1), a hormonal activator of adenyl cyclase, stimulates insulin gene transcription, an effect mediated by the cAMP response element (CRE) of the rat insulin I gene promoter (RIP1). Here we demonstrate that the signaling mechanism underlying stimulatory effects of GLP-1 on insulin gene transcription results from protein kinase A (PKA)-independent activation of the RIP1 CRE. Although GLP-1 stimulates cAMP production in rat INS-1 insulinoma cells, we find accompanying activation of a -410-bp RIP1 luciferase construct (-410RIP1-LUC) to exist independently of this second messenger. GLP-1 produced a dose-dependent stimulation of -410RIP1-LUC (EC50 0.43 nmol/l), an effect reproduced by the GLP-1 receptor agonist exendin-4 and abolished by the antagonist exendin(9-39). Activation of RIP1 by GLP-1 was not affected by cotransfection with dominant-negative Gs alpha, was not blocked by cAMP antagonist Rp-cAMPS, and was insensitive to PKA antagonist H-89. Truncation of -410RIP1-LUC to generate -307-, -206-, and -166-bp constructs revealed 2 segments of RIP1 targeted by GLP-1. The first segment, not regulated by forskolin, was located between -410 and -307 bp of the promoter. The second segment, regulated by both GLP-1 and forskolin, included the CRE and was located between -206 and -166 bp. Consistent with these observations, stimulatory effects of GLP-1 at RIP1 were reduced after introduction of delta-182 and delta-183/180 inactivating deletions at the CRE. The action of GLP-1 at -410RIP1-LUC was also reduced by cotransfection with A-CREB, a genetically engineered isoform of the CRE binding protein CREB, which dimerizes with and prevents binding of basic-region-leucine-zipper (bZIP) transcription factors to the CRE. In contrast, the action of GLP-1 at the CRE was not blocked by cotransfection with M1-CREB, an isoform that lacks a consensus serine residue serving as substrate for PKA-mediated phosphorylation. On the basis of these studies, it is proposed that PKA-independent stimulatory actions of GLP-1 at RIP1 are mediated by bZIP transcription factors related in structure but not identical to CREB.

Insulinotropic glucagon-like peptide 1 agonists stimulate expression of homeodomain protein IDX-1 and increase islet size in mouse pancreas

Diabetes is caused by a failure of the pancreas to produce insulin in amounts sufficient to meet the body's needs. A hallmark of diabetes is an absolute (type 1) or relative (type 2) reduction in the mass of pancreatic beta-cells that produce insulin. Mature beta-cells have a lifespan of approximately 48-56 days (rat) and are replaced by the replication of preexisting beta-cells and by the differentiation and proliferation of new beta-cells (neogenesis) derived from the pancreatic ducts. Here, we show that the insulinotropic hormone glucagon-like peptide (GLP)-1, which is produced by the intestine, enhances the pancreatic expression of the homeodomain transcription factor IDX-1 that is critical for pancreas development and the transcriptional regulation of the insulin gene. Concomitantly, GLP-1 administered to diabetic mice stimulates insulin secretion and effectively lowers their blood sugar levels. GLP-1 also enhances beta-cell neogenesis and islet size. Thus, in addition to stimulating insulin secretion, GLP-1 stimulates the expression of the transcription factor IDX-1 while stimulating beta-cell neogenesis and may thereby be an effective treatment for diabetes.

Re-evaluation of anion-exchange HPLC for the analysis of acidic compounds

A number of weak and strong anion-exchange HPLC phases have been evaluated for the analysis of acidic drugs and related compounds. Using eluents with high organic content, reasonable chromatography could be obtained and widely differing compounds easily separated in isocratic mode. Retention was related to solute pKa and concentration of ammonium acetate in the eluent. All the phases showed an unexplained loss in retention with repeated use, although with one material; nucleosil SAX, this was low (15%) and considered acceptable. This material was also shown to be relatively stable under typical bioanalytical conditions.

Consolidation behavior of an experimental, cross-linked polyalkyl ammonium polymer

The effect of various factors (i.e., particle size, lubricant, moisture, and excipients) on the tableting properties of DMP 504 powder, an experimental, cross-linked polyalkyl ammonium polymer, was studied using an instrumented single-punch tablet press. The results indicate that plastic deformation is the primary consolidation mechanism for DMP 504. Lubrication of DMP 504 with magnesium stearate resulted in negative interaction in compactibility. The increase in tablet hardness with increase in water content of DMP 504 (up to 2.5%) could be attributed to the lubricating effect of water. Increasing the water content above the optimum moisture range (i.e., 2.5% to 4.0%) caused a drastic reduction in tablet crushing strength due to the hydrodynamic resistance. A mixture of DMP 504 with microcrystalline cellulose or starch led to a positive interaction with respect to compactibility. A deviation in tablet strength from the linear interpolated value did not correspond to a deviation in tablet thickness. The improved compactibility for the mixture of DMP 504 and microcrystalline cellulose or starch is not related directly to the facilitated densification.

Glucagon gene transcription activation mediated by synergistic interactions of pax-6 and cdx-2 with the p300 co-activator

In the endocrine pancreas, alpha-cell-specific expression of the glucagon gene is mediated by DNA-binding proteins that interact with the proximal G1 promoter element, which contains several AT-rich domains. The homeodomain transcription factors brain-4, pax-6, and cdx-2 have been shown to bind to these sites and to transactivate glucagon gene expression. In the present study, we investigated the interaction of cdx-2 and pax-6 with p300, a co-activator coupled to the basal transcription machinery. In transient transfection-expression experiments, we found that the transactivating effects of cdx-2 and pax-6 on the glucagon gene were greatly enhanced by the additional expression of p300. This enhancement was due to direct protein-protein interactions of both pax-6 and cdx-2 with the N-terminal C/H1 domain of p300. pax-6 and cdx-2 also directly interacted with one another at the protein level. pax-6, bound to its DNA recognition site in the glucagon G1 promoter element, tethered cdx-2 to the molecular complex of pax-6 and p300. Further, we found that the presence of cdx-2 enhanced the interaction of pax-6 with p300, thus establishing a molecular complex of transcription factors implicated in tissue-specific glucagon gene expression with the basal transcriptional machinery.

Photoinduced particulate matter in a parenteral formulation for bisnafide, an experimental antitumor agent

This paper assesses the cause of particulate formation in vials of the experimental antitumor agent bisnafide and investigates pharmaceutical techniques to reduce the number of particulates in the product. Solution preparation and particulate isolation were performed under Class 100 laminar air flow. Reversed-phase HPLC and infrared microscopy were used to characterize drug and isolated particulate matter, whereas a Hiac particle counter was used to quantify the particulate matter. Particulate matter was observed following agitation of the drug solutions and was found to be associated with specific lots of drug substance. HPLC of the isolated particulate matter indicated that the particulates consisted largely of bisnafide and impurities that were identified as the products of photodegradation, confirmed to be the result of the photolytic cleavage of bisnafide to form a poorly soluble aldehyde. The aldehyde may, in turn, interact with bisnafide molecules to form the particulate matter as suggested by the observed pH-dependent reversibility of the particulate phenomenon. The particulate matter could be reduced by protecting solutions of bisnafide from light during chemical synthesis and production of the dosage form and, alternatively, by reducing the solution pH to 3.0 or less, addition of surfactants below their critical micelle concentration, and removal of impurities by froth flotation of the bisnafide solutions.

Simultaneous chemotherapy and radiotherapy with escalating doses of chemotherapy in patients with advanced esophageal carcinoma

From January 1992 to January 1995, 39 patients were diagnosed with esophageal carcinoma at the Department of Veterans Affairs Medical Center in Washington, D.C. All of the patients were men aged 44 to 78, and the median age was 66. Staging included a physical examination, serum chemistries, barium swallow, endoscopy with biopsy, and computed tomographic scans of the chest and abdomen. Seven patients were ineligible for the study because they had poor performance status, refused treatment, or received treatment at another medical center. All the patients treated had a performance status of 1 to 2. In 1992, 15 patients received 400 mg/m2/d 5-fluorouracil; in 1993, eight patients received 500 mg/m2/d 5-fluorouracil; and in 1994, nine patients received 600 mg/m2/d 5-fluorouracil as a continuous intravenous infusion during radiotherapy, which consisted of 60 Gy over 6 to 8 weeks. The complete response rates were 26%, 25%, and 22% for 1992, 1993, and 1994, respectively. The median survival was 11 months, 14 months and 9 months for those same years, respectively. The major toxicities were hematologic. Three patients died of pneumonia during treatment. Simultaneous chemotherapy and radiotherapy is an effective mode of therapy for localized esophageal carcinoma. However, escalating doses of chemotherapy did not increase the complete response rate.

Intranasal antiplatelet/antithrombotic efficacy of a novel platelet GPIIB/IIIA receptor antagonist DMP755

This article describes the equivalent antiplatelet/antithrombotic effects of DMP755 at comparable doses by intranasal and i.v. administration but required substantially higher doses with the oral administration route. Antiplatelet and antithrombotic efficacy of DMP755 or its free acid form XV459 were determined in dogs. Arterial thrombosis models were induced either electrolytically (200 microA anodal current) in the carotid artery or mechanically by external clamping of femoral artery along with stenosis, which result in either total occlusive thrombus formation or cyclic flow reduction (CFR), respectively. Either DMP755 or its free acid form, XV459 demonstrated maximal and comparable antiplatelet efficacy at 0.025-0.1 mg/kg, intravenous (i.v.) or intranasal but not oral (PO) in mongrel dogs. The antiplatelet efficacy of DMP755 at 0.1 mg/kg, intranasal, or i.v. was determined in a cross-over design (n=8 in each group). In this study, a comparable and maximal antiplatelet efficacy for DMP755 after intranasal or i.v. was demonstrated suggesting 100% intranasal bioavailability as compared with the modest antiplatelet efficacy at 0.1 mg/kg, p.o. DMP755 administered at 0.1 mg/kg, intranasally or i.v. or at 0.3 mg/kg, p.o. prevented the incidence of electrolytic injury-induced arterial thrombosis in the carotid artery thrombosis model and prevented the incidence of cyclic flow reduction in mechanically injured and stenosed femoral artery. In conclusion, DMP755 has a comparable intranasal and intravenous antiplatelet/antithrombotic profiles along with a significant improvement over its oral profiles. These data also suggest the potential utility of intranasal DMP755 in various acute and chronic thromboembolic disorders. This is the first report of intranasal bioavailability of a glycoprotein receptor antagonist.