A contribute to the comprehension of complexing agents and salt solutions reaction mechanism on chemical attack of type I molded glass containers

The commonly named ″glass delamination″ that is flakes or particles' appearance in injectables, is an important issue sometime at the origin of recalls from the market and of possible health issues to patients. In a previous work (1) the enhancement of glass surface chemical attack was shown in type I tubing and molded borosilicate glass containers, due to the presence of complexing agents in the aqueous solution in synergy with basic pH. In any case neither flakes development nor cloudy solutions were found also in the present work, to emphasize that flakes development (delamination) is not easily correlated even with a strong glass surface chemical attack. To understand the correlation between complexing agent chemical structure and the rate of glass chemical attack, a few homologue series of carboxylic and dicarboxylic acids were investigated. We considered the presence of functional groups (NH2, COOH, OH), alkyl chain length (3 to 6 carbon atoms) and the presence of double C=C bonds. Testing conditions were performed at 0.024M constant concentration, in the 5.8 - 10 pH range, in small-volume 23 mL type I molded glass containers, by autoclaving for 1 h at 121 °C according to the European Pharmacopoeia or United States Pharmacopoeia. The extracted silicon was analyzed by inductively coupled plasma atomic emission spectrometry. The collected data confirm that both dissociation constant pKa and molecular structure of the complexing agent are determinant enhancing factors of glass surface chemical attack. The second part of the work concerns with the glass surface chemical attack in the 5.8 - 9 pH range by alkali chloride solutions (NaCl and KCl 0.9% w/v and 0.0154M) widely used in parenteral therapies. For reason of completeness, this last research was extended also to LiCl and CsCl even if not used in injectables, to evaluate a possible influence of the molecular weight on the glass chemical attack. A correlation between alkali chlorides molecular weight and glass chemical attack as a function of pH was found. Therefore, in a preliminary way also acetic acid and EDTA (ethylenediaminetetraacetic acid) complexing power were examined in presence of Na or Li ions, showing some different chelating propensity as a function of the alkali ion. The present research can give precious information to the chemist involved in new pharmaceutical formulation or new molecules development, to prevent or consider some possible compatibility limitation with the packaging in type I borosilicate glass containers

When listening to rain sounds boosts arithmetic ability.

Studies in the literature have provided conflicting evidence about the effects of background noise or music on concurrent cognitive tasks. Some studies have shown a detrimental effect, while others have shown a beneficial effect of background auditory stimuli. The aim of this study was to investigate the influence of agitating, happy or touching music, as opposed to environmental sounds or silence, on the ability of non-musician subjects to perform arithmetic operations. Fifty university students (25 women and 25 men, 25 introverts and 25 extroverts) volunteered for the study. The participants were administered 180 easy or difficult arithmetic operations (division, multiplication, subtraction and addition) while listening to heavy rain sounds, silence or classical music. Silence was detrimental when participants were faced with difficult arithmetic operations, as it was associated with significantly worse accuracy and slower RTs than music or rain sound conditions. This finding suggests that the benefit of background stimulation was not music-specific but possibly due to an enhanced cerebral alertness level induced by the auditory stimulation. Introverts were always faster than extroverts in solving mathematical problems, except when the latter performed calculations accompanied by the sound of heavy rain, a condition that made them as fast as introverts. While the background auditory stimuli had no effect on the arithmetic ability of either group in the easy condition, it strongly affected extroverts in the difficult condition, with RTs being faster during agitating or joyful music as well as rain sounds, compared to the silent condition. For introverts, agitating music was associated with faster response times than the silent condition. This group difference may be explained on the basis of the notion that introverts have a generally higher arousal level compared to extroverts and would therefore benefit less from the background auditory stimuli

Percentages of correct recognition of right and wrong arithmetic results as a function of operation difficulty and type of background auditory stimuli.

<p>There was no effect of the background auditory stimuli on hits during the solving of easy arithmetical operations (the “ceiling effect)”.</p

Mean scores obtained by the two groups of participants in the three dimensions measured by the <i>Eysenck Personality Inventory</i> (Eysenck & Eysenck, 1965): Standard deviation values are reported in italics.

<p>Mean scores obtained by the two groups of participants in the three dimensions measured by the <i>Eysenck Personality Inventory</i> (Eysenck & Eysenck, 1965): Standard deviation values are reported in italics.</p

Percentages of correct recognition of right and wrong arithmetic results as a function of operation difficulty (left).

<p>Response times relative to the correct recognition of right and wrong arithmetic results as a function of operation difficulty (right).</p

Mean response times (in ms) recorded as a function of the type of background auditory stimuli and operation difficulty.

<p>Notably, the background auditory stimuli had no effect on RTs during the solving of easy arithmetical operations (the “floor effect”).</p

Mean response times (in ms) recorded as a function of group (extroverts vs. introverts) and background auditory stimuli.

<p>The auditory stimulation had a stronger “Mozart” (alerting) effect on extroverts.</p

Mean response times (in ms) recorded as a function of background auditory stimuli, result correctness and operation difficulty.

<p>Auditory stimulation quickened responses only when the operations were difficult.</p