Polymer sorption of nitroglycerin and stability of molded nitroglycerin tablets in unit-dose packaging

Nitroglycerin trapping in melamine matrices

Melamine (Mel) was used as host matrix for liquid nitroglycerin (NG), to prepare Mel/NG solid powdered compounds containing up to 45 wt% of this explosive. The two preparation processes used for this purpose consisted in evaporating a solution of both components, either in ambient conditions or under reduced pressure by the Spray Flash-Evaporation (SFE) process. In Mel/NG materials, amorphous nitroglycerin is distributed in the crystallized melamine matrix as inclusions, which were found to be smaller in size in the material prepared by the SFE process. Mel/NG materials are not stable over time: they gradually lose the nitroglycerin they contain by evaporation.

Plastic particles in medicine: A systematic review of exposure and effects to human health

Single-use plastics (SUPs) have become an essential constituent of our daily life. It is being exploited in numerous pharmaceutical and healthcare applications. Despite their advantages and widespread use in the pharma and medical sectors, the potential clinical problems of plastics, especially the release of micro-nanoplastics (MNPs) and additives from medical plastics (e.g. bags, containers, and administrative sets) and sorption of drugs remain understudied. Certainly, the MNPs are multifaceted stressors that cause detrimental effects to the ecosystem and human health. The origin and persistence of MNPs in pharmaceutical products, their administration to humans, endurance and possible health implication, translocation, and excretion have not been reviewed in detail. The prime focus of this article is to conduct a systematic review on the leaching of MNPs and additives from pharmaceutical containers/administrative sets and their interaction with the pharmaceutical constituents. This review also explores the primary and secondary routes of MNPs entry from healthcare plastic products and their potential health hazards to humans. Furthermore, the fate of plastic waste generated in hospitals, their disposal, and associated MNPs release to the environment, along with preventive, and alternative measures are discussed herein.

Open-Label Study of the Stability of Sublingual Nitroglycerin Tablets in Simulated Real-Life Conditions

Contemporary practice favors refilling sublingual nitroglycerin (SL NTG) every 3 to 6 months. This recommendation is based on antiquated data that does not consider the reformulated tablet and the improved manufacturing process. Our objective was to investigate the stability of SL NTG over time using simulated real-life scenarios in comparison to controlled storage conditions. This was an open-label study of 100- and 25-count commercial SL NTG bottles stored in either controlled temperature and relative humidity conditions, or carried in a pocket or purse. SL NTG potency (chemical stability) was assessed using high performance liquid chromatography and physical stability was assessed by changes in tablet weights over time through the labeled expiration date. Both chemical and physical stability of SL NTG were affected by environmental and physical factors. High temperature storage resulted in the most rapid loss of potency. Tablets carried in a pant pocket lost potency faster than those carried in a purse. Potency was also dependent on headspace of the bottle. Tablets stored in the original bottle in a temperate environment could be expected to maintained potency for more than 2 years when carried in a purse, irrespective of package size. When carried in a pant pocket, potency of a 25-count bottle was maintained for 2 years, whereas potency of a 100-count bottle fell below acceptable limits at 12 months. In conclusion, since potency is dependent on temperature, headspace, and carrying practices, frequency of SL NTG refills should be based on individual patient behavior.

Sorptive loss of volatile and gaseous anesthetics from in vitro drug application systems

In in vitro pharmacological experiments, determination of effective concentration values for various anesthetics depends on understanding the exact concentration of the drugs dissolved in physiological solutions. Actual anesthetic concentration may differ from expectations because of drug adsorption, absorption or other loss, especially in tubing. We tested the hypothesis that delivered concentrations of anesthetics decrease when solutions pass through laboratory tubing and investigated such loss by measuring the entering and exiting dissolved concentrations of two volatile (sevoflurane and isoflurane) and two gaseous (nitrous oxide and xenon) anesthetics. We tested solutions passed through tubes (1 m x 2 mm ID x 4 mm OD) made of five different materials (glass, Teflon, polyethylene (PE), polyvinyl chloride (PVC), and silicon rubber). Exiting concentrations of anesthetics were significantly reduced when they were passed through PVC (>33%) and silicon (>43%) tubes. There were no decreases in anesthetic concentrations with glass, Teflon, or PE tubes. When sevoflurane solution flowed through PVC and silicon tubes, it took 20 and 30 min, respectively, after start of flow until the anesthetic loss became negligible. These results indicate that frequently used PVC and silicon tubes, whereas flexible and easy to handle, have serious drawbacks when used in inhaled anesthetic pharmacology experiments.

Influence of intravenous administration set composition on the sorption of isosorbide dinitrate

The influence of the composition of administration sets on the sorption of isosorbide dinitrate was investigated in-vitro. Isosorbide dinitrate solutions (250 micrograms mL-1) in 0.9% NaCl or 10% glucose were stored in glass containers and administered at a flow rate of 20 mL h-1. The influence of the concentration of different plasticizers (di-ethylhexylphthalate, tri-ethylhexyltrimelitate) in polyvinylchloride tubings was determined. Polybutadiene tubings of different mol. wt coextruded laminates of these polybutadienes with PVC of different composition and a polyethylene tubing were evaluated. The higher the Shore hardness of the PVC tubing, the lower the sorption. The infusion fluid played an additional role only for the tubings with high Shore hardness (greater than 70). The sorption of isosorbide dinitrate to polybutadiene tubings of different mol. wt was less than 2.5% after 5 h and was comparable with the sorption to the polyethylene tubing. When polybutadiene/PVC laminates were used, the sorption increased significantly and was in most cases dependent on the Shore hardness of the PVC (higher Shore hardness gave lower sorptions) and on the mol. wt of the polybutadiene (lower mol. wt resulted in higher sorption). Sorption was not dependent on the type of PVC plasticizer.

The sorption of isosorbide dinitrate to intravenous delivery systems

The sorption of isosorbide dinitrate from 0.9% sodium chloride and 10% glucose solutions, by intravenous delivery systems has been investigated under simulated infusion conditions. Isosorbide dinitrate was stable in both 0.9% sodium chloride and 10% glucose solutions. Intravenous fluid containers, burettes, a syringe, infusion sets and end-line filters were evaluated. Glass containers, methacrylate butadiene styrene burettes and polybutadiene giving sets did not sorb isosorbide dinitrate. Neither did polypropylene syringes when a 10% glucose solution was used. The sorption of isosorbide dinitrate to end-line filters was unimportant but there was a significant loss to the PVC tubing used to connect the filter housing to the catheter.

Effect of nitroglycerin-soluble additives on the stability of molded nitroglycerin tablets

Nitroglycerin vapor pressures at 25 degrees C were determined for additive-nitroglycerin systems over the additive-nitroglycerin weight ratio range of 0.5 to 3.0 for 16 additives exhibiting solubility in nitroglycerin. The effects of the additives on nitroglycerin chemical stability at 25 degrees C and 50 degrees C were also studied. Tablet stability characteristics, i.e., content uniformity, open-dish stability, and chemical decomposition were evaluated for selected tablet formulations. Most additives lowered the vapor pressure of nitroglycerin sufficiently to stabilize content uniformity when used at additive-nitroglycerin weight ratios near 1. Higher additive levels are needed for significant potency stabilization in open-dish stability tests, but these levels normally decrease the chemical stability of nitroglycerin. However, stabilization of content uniformity, a twofold reduction of potency loss in an open-dish stability test, and chemical stability are possible with at least three of the additives studied.

Pharmaceutical considerations of nitroglycerin

During the past few years, there have been rapid changes in the pharmaceutical uses of nitroglycerin. New dosage forms and new delivery systems have become available, which have resulted in potential confusion to all concerned with the proper use of these systems. The goal of this review is to prevent confusion and to bring all the relevant information together. The various analytical techniques available for quality control of the dosage forms and for the study of the pharmacokinetics are reviewed, with the intent of enabling the reader to identify pertinent references rapidly. The interaction of nitroglycerin with packaging and plastic delivery devices is also reviewed so that the reader can make informed choices. Finally, the clinical pharmacy and pharmacokinetics are reviewed so as to bring the reader up to date in that area. After reading this article, the areas of nitroglycerin research that still need to be explored should be apparent.

Stability of intravenous nitroglycerin solutions

The stability of intravenous nitroglycerin solutions prepared from either sublingual tablets or a 10% nitroglycerin-lactose adsorbate (powder) was examined under various conditions. Nitroglycerin concentration was measured by high-pressure liquid chromatography. Nitroglycerin stock solutions (0.8-1.0 mg/ml) prepared from tablets or powder in either 0.9% saline were stored upright in refrigerated multidose vials for 6 months without a significant decrease in concentration. Storage of the solutions at room temperature resulted in a 20% loss after 3 months. Intravenous nitroglycerin solutions (0.2 mg/ml) prepared from tablets or powder in 0.9% saline or 5% dextrose in water were stored in glass intravenous bottles at temperatures between 6 and 38 degrees for 24 hr with a maximum loss of 18%. Stability was not affected by light. Solutions in contact with rubber stoppers, plastic intravenous bags, or plastic administration sets exhibited decreased nitroglycerin concentration characteristic of sorption. Nitroglycerin concentrations decreased to a greater extent when the administration sets were equipped with plastic burets. Brief contact of nitroglycerin solutions with a plastic syringe did not result in decreased concentration. The stability of intravenous nitroglycerin solutions packaged in glass was not dependent on light, the vehicle, or the source of nitroglycerin. Contact with rubber or plastic surfaces should be minimized.

Nitroglycerin stability: effects on bioavailability, assay and biological distribution

The solution, absorptive, and adsorptive properties of nitroglycerin are related to problems encountered in the intravenous use of solutions of the drug and in its assay in biological tissues. Solutions of the drug in usual intravenous fluids are quite stable to hydrolysis under neutral conditions. Loss to plastic intravenous delivery set components by rapid adsorption and slower absorption processes present a significant clinical problem. Assay of the drug and its major metabolites is complicated by problems of extraction related to the solubility of nitroglycerin, its metabolites and substances in the plasma. Loss of nitroglycerin incubated with red blood cells is a very rapid process (half-life 4.0 min. at 10 ng/ml). The mechanism appears to be a physical process rather than an enzymatic one. The loss to blood cells and perhaps other biological materials should be considered in an analysis of the distribution of the drug.

The availability of nitroglycerin from parenteral solutions

The availability of nitroglycerin from solution infused from Viaflex plastic infusion bags or glass infusion bottles through Buretrol plastic giving sets has been examined. Each of the individual components of the infusion bag/giving set system (i.e. infusion bag, burette and infusion tubing) sorbed nitroglycerin to a significant extent. It was found that the event and rate of nitroglycerin disappearance from solutions stored in each of the components were in the rank order: tubing greater than burette greater than infusion bag. The disappearance kinetics of nitroglycerin from solutions stored in each component was more accurately described by a 'diffusion' model than by the 'two compartment kinetic' model reported previously. The dimensions of the components and the volume of solution used were determinants of the rate and extent of nitroglycerin disappearance. In simulated infusions of nitroglycerin through plastic infusion bag (or glass bottle)/giving set system the flow rate of solution through the plastic infusion tubing affected the concentration of nitroglycerin in the effluent and the extent of sorption by the components of the infusion delivery system. The loss of nitroglycerin in these studies could be accounted for solely by the sorption of nitroglycerin by the plastic components of the infusion bag/giving set system.

Rapid and accurate stability-indicating assay for nitroglycerin

A rapid high-pressure liquid chromatographic method for determining the nitroglycerin concentration in liquid dosage forms and intravenous admixture solutions is presented. A coefficient of variation of less than 1.8% was achieved over the concentration range most commonly encountered (50-500 microgram/ml). A variable wavelength detector (lambda = 218 nm) and a micro-alkyl phenyl column were employed. The mobile phase was acetonitrile-tetrahydrofuran-water (26:10:64). Total analysis time was 12 min.