Stability of Reconstituted Telavancin Drug Product in Frozen Intravenous Bags

Background and Objective:

Intravenous (IV) infusions of telavancin for injection are generally administered in-hospital, but in some circumstances they may be administered in an outpatient environment. In that setting, antibiotics may be premixed and frozen. This study determined the chemical stability of nonpreserved telavancin in various commonly used reconstitution diluents stored in IV bags (polyvinyl chloride [PVC] and PVC-free) at -20°C (-4°F) without light.

Methods:

Telavancin (750 mg/vial) was reconstituted with 5% dextrose injection USP (D5W) or 0.9% sodium chloride injection USP (NS) to obtain drug solutions at approximately 15 mg/mL. Infusion solutions of telavancin at diluted concentrations of 0.6 mg/mL and 8.0 mg/mL covering the range utilized in clinical practice were prepared in both PVC and PVC-free IV bags using D5W or NS solutions. The infusion solutions were stored under frozen conditions (-20°C ± 5°C [-4°F ± 41°F]) and the chemical stability was evaluated for up to 32 days. Telavancin concentration, purity, and degradant levels were determined using a stability-indicating high-performance liquid chromatography (HPLC) method.

Results:

Telavancin IV infusion solutions in D5W or NS at 0.6 mg/mL and 8 mg/mL and stored at -20°C (-4°F) met the chemical stability criteria when tested on days 0, 7, 14, and 32. The assayed telavancin concentration at each time point was within 97% to 103% of the initial mean assay value. The total degradants quantified by the HPLC stability-indicating method did not show any significant change over the 32-day study period.

Conclusion:

Telavancin IV infusion solutions (in D5W or NS) in both PVC and PVC-free IV bags were stable for at least 32 days when stored at -20°C (-4°F) without light. These results provide prolonged frozen stability data further to that previously established for 7 days under refrigerated conditions (2°C-8°C [36°F -46°F]), and for 12 hours at room temperature when diluted into IV bags containing D5W, NS, or lactated Ringer’s solution.     

Isolated pituitary granuloma by atypical Mycobacterium in a nonimmunosuppressed woman

A 32-year-old woman presented with a 10-day history of fever (38.0 degrees C), headaches, nausea, vomiting and a 6-month history of diabetes insipidus and amenorrhoea. Two months previously she had undergone a surgical drilling of the right mastoid area because of mastoiditis. Endocrine investigation showed elevated serum prolactin levels, secondary adrenal and gonadal failure and a normal thyroid function. Cranial MRI scan revealed a contrast enhancing intrasellar mass (approximately 2 cm) of heterogeneous appearance with suprasellar extension and thickening of the pituitary stalk. Lumbar puncture was suggestive of aseptic meningitis. The Ziehl-Neelsen stain of cerebrospinal fluid (CSF) and the tuberculin skin test were both negative. The pituitary mass was removed with a transsphenoidal approach. Histological examination demonstrated destruction of the adenohypophysis by epithelioid granulomas with partial caseous necrosis and microabscess formation, suggestive of a mycobacterial infection. A polymerase chain reaction analysis performed on paraffin-embedded tissue was positive for mycobacterial DNA. According to the individual 16S sequence, it was identified as Mycobacterium malmoense, an atypical nontuberculous mycobacterium (NTM). In conclusion, this is the first case of an isolated pituitary granuloma caused by an NTM infection in a nonimmunosuppressed patient.     

AMP-activated protein kinase regulates hERG potassium channel

Besides their role in cardiac repolarization, human ether-a-go-go-related gene potassium (hERG) channels are expressed in several tumor cells including rhabdomyosarcoma cells. The channels foster cell proliferation. Ubiquitously expressed AMP-dependent protein kinase (AMPK) is a serine-/threonine kinase, stimulating energy-generating and inhibiting energy-consuming processes thereby helping cells survive periods of energy depletion. AMPK has previously been shown to regulate Na⁺/K⁺ ATPase, Na⁺/Ca²⁺ exchangers, Ca²⁺ channels and K⁺ channels. The present study tested whether AMPK regulates hERG channel activity. Wild type AMPK (α1β1γ1), constitutively active ^γR70QAMPK (α1β1γ1(R70Q)), or catalytically inactive ^αK45RAMPK (α1(K45R)β1γ1) were expressed in Xenopus oocytes with hERG. Tail currents were determined as a measure of hERG channel activity by two-electrode-voltage clamp. hERG membrane abundance was quantified by chemiluminescence and visualized by immunocytochemistry and confocal microscopy. Moreover, hERG currents were measured in RD rhabdomyosarcoma cells after pharmacological modification of AMPK activity using the patch clamp technique. Coexpression of wild-type AMPK and of constitutively active ^γR70QAMPK significantly downregulated the tail currents in hERG-expressing Xenopus oocytes. Pharmacological activation of AMPK with AICAR or with phenformin inhibited hERG currents in Xenopus oocytes, an effect abrogated by AMPK inhibitor compound C. ^γR70QAMPK enhanced the Nedd4-2-dependent downregulation of hERG currents. Coexpression of constitutively active ^γR70QAMPK decreased membrane expression of hERG in Xenopus oocytes. Compound C significantly enhanced whereas AICAR tended to inhibit hERG currents in RD rhabdomyosarcoma cells. AMPK is a powerful regulator of hERG-mediated currents in both, Xenopus oocytes and RD rhabdomyosarcoma cells. AMPK-dependent regulation of hERG may be particularly relevant in cardiac hypertrophy and tumor growth.     

Salecan-Clay Based Polymer Nanocomposites for Chemotherapeutic Drug Delivery Systems; Characterization and In Vitro Biocompatibility Studies

Salecan is a microbial polysaccharide suitable to obtain hydrogel for biomedical applications due to the excellent hydrophilicity and biocompatibility properties. In this work, Salecan of different concentrations was introduced into polymethacrylic acid (PMAA) in the presence of clay to form novel semi synthetic hydrogel nanocomposites systems and loaded afterwards with doxorubicin (DOX). The physical–chemical characteristics of the nanocomposites systems and their effect on the viability, and morphology of MDBK (Madin–Darby bovine kidney), HT-29 human colorectal adenocarcinoma and Colo 205 human colon adenocarcinoma cell lines were investigated. DOX release from the nanocomposite systems, cell up-take and subsequent effect on cell proliferation was also analyzed. It was found that Salecan concentration determined the swelling behavior, structural parameters and morphological features of the nanocomposite systems. The hydrogen bonds strongly influenced the formation of PMAA–Salecan–clay systems, each component bringing its own contribution, thus demonstrating the achievement of an advanced crosslinked network and a more compacted hydrogel nanocomposite morphology. All the synthesized nanocomposites had negligible toxicity to normal MDBK cells and chemoresistent HT-29 cell line, whereas in the case of Colo 205 cells a decrease by 40% of the cell viability was obtained for the sample containing the highest amount of Salecan. This effect was correlated with the lowest pore size distribution leading to highest available specific surface area and entrapped amount of DOX which was further released from the nanocomposite sample. Corroborating all the data it can be suggested that the synthesized nanocomposites with Salecan and clay could be good candidates as vehicles for chemotherapeutic agents.