Dissolution Testing of Hardly Soluble Materials by Surface Sensitive Techniques: Clotrimazole from an Insoluble Matrix

Purpose

The low aqueous solubility of many drugs impedes detailed investigation as the detection limit of standard testing routines is limited. This is further complicated within application relevant thin films typical used in patches or stripes for buccal or topical routes.

Methods

In this work a model system is developed based on spin – casting technique allowing defined clotrimazole and clotrimazole – polystyrene composite films preparation at a solid surface. Various highly sensitive techniques including quarz crystal microbalance (QCM), X-ray reflevtivity (XRR) and X-ray photon spectroscopy (XPS) are used to investigate the drug release over time into an aqueous media.

Results

The results reveal a steady drug release for both samples over the course of the experiments but with the release from the composite being significantly slower. In addition the dissolution rate of the clotrimazole sample initially increases up to 30 min after which a decrease is noted. XRR shows that this is a result of surface roughening together with film thickness reduction. The results for the composite show that the release in the composite film is a result of drug diffusion within the matrix and collapsing PS film thickness whereby XPS shows that the amount of clotrimazole at the surface after 800 min immersion is still high.

Conclusion

It can be stated that the applied techniques allow following low mass drug release in detail which may also be applied to other systems like pellets or surface loaded nano-carriers providing information for processing and application relevant parameters.     

Establishment,characterization and fibre outgrowth of isolated bovine adrenal medullary cells in long-term cultures

Medullary cells were enzymatically dissociated from adult bovine adrenal medullae by a perfusion technique using collagenase and maintained in culture for up to 4 weeks. The perfusion technique was a simplified modification of that described by Livett & Co-Workers (Fenwick, Fajdiga, Howe & Livett, 1978) and included cyclical perfusions of cortex-free medullae via the central vein at 37 C for up to 90 min with three 30 ml batches of 0.5% collagenase-containing phosphate buffered saline or Hanks's balanced salt solution and a final trituration step of the minced tissue. The cells were cultured on collagen-coated glass coverslips in modified Rose chambers, on collagen-coated Petri dishes or in Falcon flasks, studied by phase contrast and electron microscopy, catecholamine cytochemistry and assayed for adrenaline and noradrenaline.When grown on collagen about 50% of the catecholamine-storing cells extended short, broad processes as judged by catecholamine cytochemistry using the glyoxylic acid method. These processes rarely grew longer than 60 μm and many of them were seen to retract after 1 week in culture. Process formation was more pronounced and increased with time, when cells were grown on plastic surfaces. Fifteen to 20% of these cells formed long varicose axons after 18 days in culture. Fibre outgrowth from bovine chromaffin cells was also observed, when pieces of medullary tissue were transplanted on to the sympathetically denervated iris in the anterior eye chamber of Nunu mice.Addition of either nerve growth factor (10–1000 ng/ml 2.5S nerve growth factor) or antibodies to nerve growth factor (1.5 μg/ml) did not affect fibre outgrowth in vitro.Ultrastructural examinations revealed that the vast majority of cells in our cultures were typical chromaffin cells. Using the different densities of primary and secondary amine storing granular vesicles as a criterion for distinguishing noradrenaline- and adrenaline-containing cells we found a significant decrease in the number of adrenaline-containing cells with time. By 3 weeks virtually all chromaffin cells contained storage vesicles typical of noradrenaline. Chromaffin storage vesicles appeared to be more densely packed and the amount of rough endoplasmic reticulum was increased in cells treated with nerve growth factor.Results obtained by biochemical analyses indicated that chromaffin cells lost about 50% of their original amine content and stored equal amounts of noradrenaline and adrenaline from day 9 onwards compared to an initial noradrenaline/adrenaline ratio of approximately 1:6. Administration of nerve growth factor did not significantly alter the proportion and levels of adrenaline and noradrenaline in cultured bovine chromaffin cells.This investigation reveals that the capacity of bovine catecholamine-storing cells to form neurite-like processes differs considerably from that which corresponding cells from young rat adrenal medullae exhibit in vitro (Unsicker, Krisch, Otten & Thoenen, 1978 b). Chromaffin cells from adult bovine adrenal medullae kept in culture retain a large number of features typical of differentiated cells over a considerable length of time. Thus they may be profitably used to study long-term effects of drugs and interactions with other cells at morphological and biochemical levels.     

Theoretical approaches to physical transformations of active pharmaceutical ingredients during manufacturing processes

Processing-induced transformations (PITs) during pharmaceutical manufacturing are well known but difficult to predict and often difficult to control. This review of the concepts of transformations is couched in terms of the issues associated with identifying rate-controlling events from the materials side and the processing side. Specifically, the approach is reconciling the characteristic time scale of the structural change(s) in the material with the time scale of the processing-induced stress. This is definitely a model (or rather a melding of a group of existing theories) in development. This overview is a 'snapshot' of the authors' attempts to identify the categories of existing theories needed to encompass all of the relevant events for each possible PIT. The ultimate goal is to establish a framework of concepts and theories for consideration, discussion, and modeling of PITs as well as to locate much of the relevant literature in the framework.     

Fimbrolide-coated antimicrobial lenses: their in vitro and in vivo effects

PURPOSE: To examine the ability of contact lenses coated with fimbrolides, inhibitors of bacterial quorum sensing, to prevent microbial adhesion and their safety during short-term clinical assessment. METHODS: A fimbrolide was covalently attached to commercially available high Dk contact lenses. Subsequently Pseudomonas aeruginosa, Staphylococcus aureus, Serratia marcescens, or Acanthamoeba sp. were added to the lenses and control uncoated contact lenses. Lenses plus microbes were incubated for 24 h, then washed thoroughly to remove non-adherent microbes. Lenses were macerated and resulting slurry plated onto agar plates. After appropriate incubation, the numbers of colony forming units of bacteria (or numbers of Acanthamoeba trophozoites measured using a hemocytometer) from fimbrolide-coated and uncoated lenses were examined. A Guinea Pig model of lens wear was used to assess the safety of lenses worn on a continuous basis for 1 month. In a separate study, 10 subjects wore fimbrolide-coated lenses for 24 h. The responses of the Guinea Pigs and human volunteers to the lenses were assessed by slit lamp examination. RESULTS: The fimbrolides-coated lenses reduced the adhesion of all bacterial strains tested, with reductions occurring of between 67 and 92%. For Acanthamoeba a reduction of 70% was seen. There were no significant differences in ocular responses to fimbrolide-coated lenses compared with controls in either the 1 month animal model or overnight human trial. CONCLUSIONS: Fimbrolide-coated lenses show promise as an antibacterial and anti-acanthamoebal coating on contact lenses and appear to be safe when worn on the eye in an animal model.     

Hematopathological features of acute erythremia (morbus Di Guglielmo). A contribution to the classification and differential diagnosis of erythroid neoplasias

Classification and differential diagnosis of erythroid neoplasias still are a matter of discussion. Eleven cases of primary acute erythremia were diagnosed between 1981 and 1984 at the Institute of Pathology, University of Kiel. Erythremia represented 0.5% of all hematological diagnoses and 1.0% of the myeloproliferative disorders. The male-to-female ratio was 1:1. Incidence peaked in the 7th decade. Evaluation of clinical data, of cytological and histological findings in blood and bone marrow, and of occasional immunophenotyping of blast cells (anti-glycophorin A+) revealed two variants of acute erythremia: a first, blastic one and a second, more differentiated form. Acute erythremia must be strictly distinguished from mixed erythroid/myeloid erythroleukemia and from secondary erythroid neoplasias, especially the erythremic 'blast crisis' of chronic myeloid leukemia or polycythemia vera rubra. Distinguishing the myelodysplastic variant of sideroblastic anemia from anerythremic acute erythremia can be extremely difficult. We discuss the differential diagnosis and classification of erythroid neoplasias based upon reproducible hematological criteria to facilitate the gathering and comparison of epidemiological and clinical data on these rare malignancies.     

Immobilized liposome layers for drug delivery applications: inhibition of angiogenesis

Liposomes were immobilized onto the surface of perfluorinated polymer tape samples and tissue culture polystyrene well-plates using a multilayer immobilization strategy. In the first step, a thin interfacial bonding layer with surface aldehyde groups was deposited from a glow discharge struck in acetaldehyde vapour. Polyethylenimine was then covalently bound onto the aldehyde groups by reductive amination, followed by covalent binding of NHS-PEG-biotin molecules onto the surface amine groups by carbodiimide chemistry. Next, NeutrAvidin™ protein molecules were bound onto the PEG-biotin layer. Finally, liposomes containing PEG-biotinylated lipids were docked onto the remaining binding sites of the surface-immobilized NeutrAvidin™ molecules. AFM was used to image surface-bound liposomes and revealed a density well below close packing. The release characteristics of the surface-bound liposomes were measured by the fluorescence intensity changes of carboxyfluorescein upon release. Liposomes filled with sodium orthovanadate were surface immobilized and used in two in vitro angiogenesis assays. Marked differences compared to various control samples were observed, demonstrating the utility of drug-filled, surface-bound liposomes for evoking localized, controlled biological host responses proximal to an implanted biomedical device.     

The effect of hypotonicity, glutamine, and glycine on red cell preservation

BACKGROUND : Red cells (RBCs) stored in hypo-os-molar additive solutions with the same concentrations of adenine, dextrose, mannitol, and sodium chloride and varied amounts of ammonium, phosphate, glycerol, and glutamine were better preserved than RBCs in the standard additive solution (Adsol). Cell swelling occurred in all the experimental additives. This observation prompted the evaluation of glutamine and glycine alone, as well as a combination of glutamine and glycine, all of which have been described as producing swelling of rat liver cells. STUDY DESIGN AND METHODS : Aliquots of RBCs were stored at 4°C in Adsol or experimental additive solutions (EASs) all containing adenine, 2 mM; dextrose, 110 mM; mannitol, 55 mM; and sodium chloride, 50 mM. EAS 42 had, in addition, glutamine, 10 mM; glycine 5 mM; and phosphate, 20 mM. EAS 43 had glutamine, 10 mM; glycine, 10 mM; and phosphate 20 mM. EAS 44 had glutamine, 10 mM; EAS 45 had glutamine, 10 mM, and phosphate, 20 mM; and EAS 46 had only glycine, 10 mM. At intervals, measurements were made of mean corpuscular volume, mean corpuscular hemoglobin concentration, morphology, ATP, hemolysis, supernatant potassium, ammonia, pH, and microvesicles shed. RESULTS : The initial mean corpuscular volumes were larger in all EASs than in Adsol, but the greatest difference was between EASs 44 and 46 (108 fL) and Adsol (86 fL) (p<0.001). The morphology scores were significantly better in all the EASs (p<0.04). The ATPs were significantly greater in all the EASs (p<0.001), and highest in those with phosphate. Potassium leakage and hemolysis were less in the EASs (p<0.001). The ammonia levels were higher in all the EASs than in Adsol, with the exception of EAS 46. During storage, the extracorpuscular and intracorpuscular pH levels were essentially identical. The shedding of microvesicles was greatly reduced in all the EASs. CONCLUSION : Cell swelling induced in RBCs after collection appears to improve preservation. Ammonia and phosphate enhance RBC ATP maintenance. Glycine decreases the formation of ammonia by RBCs stored in a hypotonic medium.     

Development of Marjolin's ulcer within one month of burn injury with synchronous primary lung squamous cell carcinoma in an elderly patient: report of a case with allelotyping

Marjolin's ulcer defines the occurrence of malignancy, usually squamous cell carcinoma, in the setting of a post-traumatic scar often following thermal injury. The latency period from the time of injury to the onset of malignant transformation averages 30 years with the earliest documented incidence occurring 6 weeks after injury. In addition, the occurrence of multiple primary malignancies is a rare event. To our knowledge, we report the first case in the literature of a well-differentiated squamous cell carcinoma developing within 1 month of thermal injury to an elderly patient's right index finger with an incidental synchronous primary lung moderately differentiated squamous cell carcinoma that was morphologically and genetically different as confirmed by allelotyping. There is scant precedent literature on acute Marjolin's ulcers, and the most acute cases have arisen 6 weeks post-burn. There is also little published literature on the incidence of multiple primary malignancies. The quoted incidence of this event is <1%. Clinicians should be aware of the possibility of malignant transformation at the site of prior thermal injury. Biopsy remains the gold standard for diagnosis for Marjolin's ulcer. MRI is the most important diagnostic imaging tool because it will demonstrate the margins and extent of the lesion. Due to the aggressive nature of Marjolin's ulcer, treatment is usually surgical and dependent upon grading. When multiple lesions are detected after staging of a presumed neoplasm, the possibility of multiple primary maligancies should be considered. Allelotyping is a process that can be utilized to determine if multiple masses are related.