Gopal Potti

Safety And Pharmacokinetics Of A Preservative-free Triamcinolone Acetonide Formulation For Intravitreal Administration

Purpose: The safety and pharmacokinetics of a triamcinolone acetonide (TA) preservative-free (TA-PF) formulation were investigated after intravitreal administration in rabbits. Methods: A TA-PF formulation was prepared as a sterile 40-mg/mL or 160-mg/mL suspension in single-use vials by adding TA powder to 0.5% hydroxypropyl methylcellulose in normal saline. TA-PF (4-mg and 16-mg doses) and Kenalog (Bristol-Myers-Squibb, Princeton, NJ) (4-mg dose) were injected into the vitreous of separate groups of rabbits, and drug levels were measured in the vitreous over time with HPLC. Ocular toxicology (clinical examination, serial electroretinography, and histopathologic analysis) was evaluated in a separate group of animals after intravitreal TA-PF injection. Results: The half-lives of the injection amount in the vitreous, 4-mg TA-PF, 16-mg TA-PF, and 4-mg Kenalog, were found to be 24 days, 39 days, and 23 days, respectively. There were no signs of toxicities by clinical examination after TA-PF injection. Serial electroretinograms of rabbits receiving either 4-mg or 16-mg intravitreal TA-PF injections remained normal over time. Histopathologic analysis showed normal ocular tissues in animals receiving either 4-mg or 16-mg intravitreal TA-PF injections. Conclusion: The half-life of TA in the vitreous after a 4-mg injection of either TA-PF or Kenalog was comparable. A 16-mg dose of TA-PF produced a long vitreous half-life, and this may be of clinical benefit in patients requiring 6 months of drug exposure in the eye for a chronic disease.

Nitrite and nitrate-dependent generation of anti-inflammatory fatty acid nitroalkenes.

A gap in our understanding of the beneficial systemic responses to dietary constituents nitrate (NO3(-)), nitrite (NO2(-)) and conjugated linoleic acid (cLA) is the identification of the downstream metabolites that mediate their actions. To examine these reactions in a clinical context, investigational drug preparations of (15)N-labeled NO3(-) and NO2(-) were orally administered to healthy humans with and without cLA. Mass spectrometry analysis of plasma and urine indicated that the nitrating species nitrogen dioxide was formed and reacted with the olefinic carbons of unsaturated fatty acids to yield the electrophilic fatty acid, nitro-cLA (NO2-cLA). These species mediate the post-translational modification (PTM) of proteins via reversible Michael addition with nucleophilic amino acids. The PTM of critical target proteins by electrophilic lipids has been described as a sensing mechanism that regulates adaptive cellular responses, but little is known about the endogenous generation of fatty acid nitroalkenes and their metabolites. We report that healthy humans consuming (15)N-labeled NO3(-) or NO2(-), with and without cLA supplementation, produce (15)NO2-cLA and corresponding metabolites that are detected in plasma and urine. These data support that the dietary constituents NO3(-), NO2(-) and cLA promote the further generation of secondary electrophilic lipid products that are absorbed into the circulation at concentrations sufficient to exert systemic effects before being catabolized or excreted.

Octanoic acid in alcohol-responsive essential tremor: A randomized controlled study

Objective: To assess safety and efficacy of an oral, single, low dose of octanoic acid (OA) in subjects with alcohol-responsive essential tremor (ET). Methods: We conducted a double-blind, placebo-controlled, crossover, phase I/II clinical trial evaluating the effect of 4 mg/kg OA in 19 subjects with ET. The primary outcome was accelerometric postural tremor power of the dominant hand 80 minutes after administration. Secondary outcomes included digital spiral analysis, pharmacokinetic sampling, as well as safety measures. Results: OA was safe and well tolerated. Nonserious adverse events were mild (Common Terminology Criteria for Adverse Events grade 1) and equally present after OA and placebo. At the primary outcome, OA effects were not different from placebo. Secondary outcome analyses of digital spiral analysis, comparison across the entire time course in weighted and nonweighted accelerometry, as well as nondominant hand tremor power did not show a benefit of OA over placebo. The analysis of individual time points showed that OA improved tremor at 300 minutes (dominant hand, F1,16 = 5.49, p = 0.032 vs placebo), with a maximum benefit at 180 minutes after OA (both hands, F1,16 = 6.1, p = 0.025). Conclusions: Although the effects of OA and placebo at the primary outcome were not different, secondary outcome measures suggest superiority of OA in reducing tremor at later time points, warranting further trials at higher dose levels. Classification of evidence: This study provides Class I evidence that a single 4-mg/kg dose of OA is not effective in reducing postural tremor in patients with ET at a primary outcome of 80 minutes, but is effective for a secondary outcome after 180 minutes.

Development of carbamazepine:phospholipid solid dispersion formulations

Abstract This study is concerned with the development of a carbamazepine (CBZ):phospholipid (PL) solid dispersion formulation with improved dissolution characteristics. CBZ powders were blended with PL to produce CBZ:PL physical mixtures or made into solid dispersions with PL by the solvent method. CBZ exhibited significantly improved dissolution rates in PL coprecipitate (coppt) as compared to the physical mixtures or CBZ alone. Dissolution studies suggested that less than 10:1 ratio of CBZ to PL (9.1% PL) was required to disperse amorphous CBZ completely in the carrier. The coppt yielded a 3.6-fold greater initial dissolution rate (computed over the 5 min of dissolution) than the pure CBZ. Also, the total amount dissolved after 60 min was 2.1-fold greater at a CBZ:dimyristoylphosphatidylglycerol (DMPG) of 10:1 ratio (9.1% DMPG) than for the corresponding pure drug. Increasing the DMPG concentration to 4:1 (20% DMPG) compositions resulted in only a further 10% increase in the initial dissolution rate and 8.5% increase in the limiting concentration. Thus, a small amount of PL improved the dissolution of CBZ to a significant level. Some effect was also observed by changing the composition of the PLs. The coppts were formulated into tablets in order to compare the dissolution profile with that of TegretolR, a commercially available tablet of CBZ. It was found that the total amount dissolved after 60 min was two-fold higher in our tablet formulation than the commercial product, TegretolR. Powder X-ray diffraction spectra showed no changes in the diffraction patterns of CBZ in the coppt. It is concluded that CBZ:PL solid dispersions may have clinical advantages of quick in-vivo release to yield better bioavailability than existing commercial formulations.

Conjugated Linoleic Acid Modulates Clinical Responses to Oral Nitrite and NitrateNovelty and Significance

Dietary NO3− (nitrate) and NO2− (nitrite) support ˙NO (nitric oxide) generation and downstream vascular signaling responses. These nitrogen oxides also generate secondary nitrosating and nitrating species that react with low molecular weight thiols, heme centers, proteins, and unsaturated fatty acids. To explore the kinetics of NO3−and NO2−metabolism and the impact of dietary lipid on nitrogen oxide metabolism and cardiovascular responses, the stable isotopes Na15NO3 and Na15NO2 were orally administered in the presence or absence of conjugated linoleic acid (cLA). The reduction of 15NO2− to 15NO was indicated by electron paramagnetic resonance spectroscopy detection of hyperfine splitting patterns reflecting 15NO-deoxyhemoglobin complexes. This formation of 15NO also translated to decreased systolic and mean arterial blood pressures and inhibition of platelet function. Upon concurrent administration of cLA, there was a significant increase in plasma cLA nitration products 9- and 12-15NO2-cLA. Coadministration of cLA with 15NO2− also impacted the pharmacokinetics and physiological effects of 15NO2−, with cLA administration suppressing plasma NO3−and NO2−levels, decreasing 15NO-deoxyhemoglobin formation, NO2−inhibition of platelet activation, and the vasodilatory actions of NO2−, while enhancing the formation of 9- and 12-15NO2-cLA. These results indicate that the biochemical reactions and physiological responses to oral 15NO3−and 15NO2−are significantly impacted by dietary constituents, such as unsaturated lipids. This can explain the variable responses to NO3−and NO2−supplementation in clinical trials and reveals dietary strategies for promoting the generation of pleiotropic nitrogen oxide-derived lipid signaling mediators. Clinical Trial Registration— URL: http://www.clinicaltrials.gov. Unique identifier: NCT01681836.

Stability of alemtuzumab solutions at room temperature

PURPOSE The 24-hour stability of alemtuzumab solutions prepared at concentrations not included in the product label and stored in glass or polyolefin containers at room temperature was evaluated. METHODS Triplicate solutions of alemtuzumab (6.67, 40, and 120 μg/mL) in 0.9% sodium chloride were prepared in either glass bottles or polyolefin containers and stored at room temperature under normal fluorescent lighting conditions. The solutions were analyzed by a validated stability-indicating high-performance liquid chromatography (HPLC) assay at time zero and 8, 14, and 24 hours after preparation; solution pH values were measured and the containers visually inspected at all time points. Stability was defined as the retention of ≥90% of the initial alemtuzumab concentration. RESULTS HPLC analysis indicated that the percentage of the initial alemtuzumab concentration retained was >90% for all solutions evaluated, with no significant changes over the study period. The most dilute alemtuzumab solution (6.67 μg/mL) showed some degradation (91% of the initial concentration retained at hour 24), whereas the retained concentration was >99% for all other preparations throughout the study period. Solution pH values varied by drug concentration but did not change significantly over 24 hours. No evidence of particle formation was detected in any solution by visual inspection at any time during the study. CONCLUSION Solutions of alemtuzumab 6.67 μg/mL stored in glass bottles and solutions of 40 and 120 μg/mL stored in polyolefin containers were stable for at least 24 hours at room temperature.

Dose-escalation study of octanoic acid in patients with essential tremor

BACKGROUND Recently, 1-octanol has been shown to have efficacy in treating patients with essential tremor (ET). The primary metabolite of 1-octanol is octanoic acid (OA), which is now thought to be the active substance that mediates tremor suppression. Our aim was to describe the maximum tolerated dose (MTD) of oral OA in patients with ET and assess the pharmacokinetics (PK) and pharmacodynamics (PD) profile of OA. METHODS The MTD was studied using an open-label, single-ascending 3 + 3 dose-escalation design. Predefined single doses ranged from 8 to 128 mg/kg, with grade 2 adverse events (AEs) defined as dose-limiting toxicity. Tremor was assessed using accelerometry, digital spiral analysis, and a standard clinical rating scale at baseline and up to 600 minutes after intake. Safety assessments and PK sampling were also performed. RESULTS Dose-limiting toxicity was not reached. The most frequent AE was mild abdominal discomfort. Exposure (AUC) increased linearly with the dose. Secondary efficacy measures suggested a dose-dependent reduction of tremor. Accordingly, a single unified PK/PD model with an effect compartment and sigmoid maximum effect (Emax) response could be built that accounted well for the time profiles of plasma concentrations as well as effects on tremor severity across the 5 dose levels. CONCLUSION Although our trial did not reach an MTD, a dose-dependent effect was demonstrated in the PK/PD model as well as in secondary efficacy outcomes. Future studies are needed to explore the safety in higher dose ranges and to confirm dose-dependent efficacy in a placebo-controlled design. TRIAL REGISTRATION Clinicaltrials.gov NCT01468948FUNDING. NINDS Intramural Research Program; TG Therapeutics Inc.

Stability of isoniazid injection in i.v. solutions

Purpose Results of an assessment of the chemical stability of isoniazid injection in 0.9% sodium chloride injection and 5% dextrose injection are reported. Methods Triplicate solutions of isoniazid (0.5 and 6.0 mg/mL) in the 2 diluents were prepared in ethylene and propylene copolymer i.v. containers and stored under light protection at room temperature (20–25 °C) or under refrigeration (2–8 °C). Standard aliquots were removed from each solution at time points up to 72 hours and analyzed via high‐performance liquid chromatography (HPLC). Stability was defined as retention of >90% of the initial isoniazid concentration; pH, osmolality, and visual appearance were assessed. Results Isoniazid 0.5‐ and 6.0‐mg/mL solutions in 0.9% sodium chloride injection were stable for up to 72 hours at room temperature or under refrigeration. HPLC analysis of isoniazid 0.5‐mg/mL solutions in 5% dextrose injection revealed a decrease to less than 90% of the initial concentration at 8 hours at room temperature and at 30 hours under refrigeration. Isoniazid 6.0‐mg/mL solutions in 5% dextrose injection were stable for 24 hours at room temperature and for 48 hours under refrigeration. The pH, osmolality, and visual appearance of the solutions were not affected. Conclusion Isoniazid solutions of 0.5 and 6.0 mg/mL in 0.9% sodium chloride injection were stable under light protection for up to 72 hours when stored at room temperature or under refrigeration. Isoniazid injection was less stable in 5% dextrose injection, especially at a concentration of 0.5 mg/mL at room temperature.

Stability of tacrolimus solutions in polyolefin containers

PURPOSE Results of a study to determine the stability of tacrolimus solutions stored in polyolefin containers under various temperature conditions are reported. METHODS Triplicate solutions of tacrolimus (0.001, 0.01, and 0.1 mg/mL) in 0.9% sodium chloride injection or 5% dextrose injection were prepared in polyolefin containers. Some samples were stored at room temperature (20-25 °C); others were refrigerated (2-8 °C) for 20 hours and then stored at room temperature for up to 28 hours. The solutions were analyzed by stability-indicating high-performance liquid chromatography (HPLC) assay at specified time points over 48 hours. Solution pH was measured and containers were visually inspected at each time point. Stability was defined as retention of at least 90% of the initial tacrolimus concentration. RESULTS All tested solutions retained over 90% of the initial tacrolimus concentration at all time points, with the exception of the 0.001-mg/mL solution prepared in 0.9% sodium chloride injection, which was deemed unstable beyond 24 hours. At all evaluated concentrations, mean solution pH values did not change significantly over 48 hours; no particle formation was detected. CONCLUSION During storage in polyolefin bags at room temperature, a 0.001-mg/mL solution of tacrolimus was stable for 24 hours when prepared in 0.9% sodium chloride injection and for at least 48 hours when prepared in 5% dextrose injection. Solutions of 0.01 and 0.1 mg/mL prepared in either diluent were stable for at least 48 hours, and the 0.01-mg/mL tacrolimus solution was also found to be stable throughout a sequential temperature protocol.

Assays for biological agents

We thank Dr. Kolesar and Mr. Vermeulen for their observation about potential differences in determining the stability of biological compounds versus simple chemical molecules. We agree that guidelines should be developed for conducting stability studies for biological agents that include a