Assessment of non-invasive tear break-up time and tear meniscus height after instillation of three different formulations of anesthetic eye drops by Oculus Keratograph 5M / Avaliação do tempo de ruptura lacrimal não invasivo e da altura do menisco lacrimal após a instilação de três diferentes formulações de colírio anestésico por Oculus Keratograph 5M

Abstract Purpose: To assess the non-invasive tear break-up time (NITBUT) and tear meniscus height (TMH) after instilling the three different types of anesthetic eye drops by Oculus Keratograph 5M. Methods: In this prospective study, 85 healthy subjects (85 eyes) were randomly divided into three groups. The groups were randomly received lidocaine hydrochloride 2%, proparacaine hydrochloride 0.5%, and tetracaine hydrochloride 0.5%. The qualitative and quantitative parameters of tear film were assessed using NITBUT and TMH, respectively. In all groups, the quantity of tear film using TMH was measured in the right eye of subjects, while the quality of tear film using NITBUT was assessed in the left eye. The analysis of variance (ANOVA) was used to compare the difference between before and after the intervention. A P-value < 0.05 was considered significant. Results: Differences for TMH and NITBUT between before and after applying lidocaine hydrochloride 2% were not statistically significant (P > 0.05). The mean values of NITBUT and TMH after the instillation of proparacaine hydrochloride 0.5% showed a significant decrease than before the intervention (P < 0.05). Also, after the use of tetracaine hydrochloride 0.5%, the mean value of NITBUT was significantly increased (P < 0.05), but the mean value of TMH was significantly decreased than before the intervention (P < 0.05). Conclusion: Our study showed that lidocaine hydrochloride 2% as an anesthetic eye drops can be an appropriate choice for eye examinations due to a lack of significant effect on the quantity and quality of tear film.

Resumo Objetivo: Avaliar o tempo de ruptura lacrimal não invasivo (NITBUT) e a altura do menisco lacrimal (TMH) após instilar os três tipos diferentes de colírio anestésico pelo Oculus Keratograph 5M. Métodos: Neste estudo prospectivo, 85 indivíduos saudáveis (85 olhos) foram divididos aleatoriamente em três grupos. Os grupos receberam aleatoriamente cloridrato de lidocaína a 2%, cloridrato de proparacaína a 0.5% e cloridrato de tetracaína a 0.5%. Os parâmetros qualitativos e quantitativos do filme lacrimal foram avaliados utilizando NITBUT e TMH, respectivamente. Em todos os grupos, a quantidade de filme lacrimal utilizando TMH foi medida no olho direito dos sujeitos, enquanto a qualidade do filme lacrimal usando NITBUT foi avaliada no olho esquerdo. A análise de variância (ANOVA) foi utilizada para comparar a diferença entre antes e depois da intervenção. Um valor de P < 0.05 foi considerado significativo. Resultados: Diferenças para TMH e NITBUT entre antes e depois da aplicação de cloridrato de lidocaína a 2% não foram estatisticamente significantes (P > 0.05). Os valores médios de NITBUT e TMH após a instilação de cloridrato de proparacaína a 0.5% mostraram uma diminuição significativa do que antes da intervenção (P < 0.05). Além disso, após o uso de cloridrato de tetracaína a 0.5%, o valor médio de NITBUT foi significativamente aumentado (P < 0.05), mas o valor médio de TMH foi significativamente menor do que antes da intervenção (P < 0.05). Conclusão: Nosso estudo mostrou que o cloridrato de lidocaína a 2% como colírio anestésico pode ser uma escolha apropriada para exames oftalmológicos devido à falta de efeito significativo sobre a quantidade e a qualidade do filme lacrimal.

Effect of tetracaine on intraocular pressure in normal and hypertensive rabbit eyes

Purpose: To evaluate the effect of tetracaine on intraocular pressure [IOP] in normal and hypertensive rabbit eyes

Methods: The study was conducted on 12 healthy rabbits as controls and 6 healthy rabbits in which an experimental model of ocular hypertension [OHT] was induced by administration of 70 mL/kg of tap water through an orogastric tube. One drop of tetracaine was instilled in the left eye while a drop of normal saline [placebo] was applied to the right eye of the control group. IOP was measured before and 0, 5, 10, 15, 20, 25, 30, 35 and 40 minutes after drop administration in this group. The OHT group also received one drop of tetracaine and normal saline in the left eyes and right eyes respectively, immediately after water loading; the instillation of drops was repeated after 55 minutes. IOP was measured before and 0, 5, 10, 15, 20, 25, 30, 35, 40, 55, 70, 85, 100 and 115 minutes after water loading in this group

Results: Tetracaine treated eyes in both groups [ocular hypertensive and normal controls] demonstrated significant IOP reduction at time zero [immediately after drop instillation] which was sustained up to 20 minutes, as compared to placebo treated eyes [P<0.05]. In ocular hypertensive rabbits, repeat instillation of tetracaine significantly reduced IOP at 55 minutes up to 30 minutes thereafter

Conclusion: Topical tetracaine can reduce IOP; this fact should be considered in experiments evaluating IOP reducing agents

Influence of antibiotics on the mechanical responses of guinea-pig ileum to acetycholine and histamine

The side effects of antibiotics have been extensively described during the last decades, however, their role on digestive motility must be better investigated. Following a line research, the influence of penicillin, chloranfenicol tetracycline and gentamicine on longitudinal snooth muscle response to acetylcholine and histamine were studied on guinea-pig ileum. There were no differences between the responses before and after the addition of each antibiotic. Further investigations must be performed in order to find a possible influence of antibiotics on digestive motility.

Antibacterial effect of tetracaine hydrochloride (Pontocaine(R)) in the aspect of exposure time: in vitro study

Antibacterial effect of tetracaine hydrochloride was studied. Tetracaine hydrochloride (preservative free) were incubated with Staphylococcus aureus, coagulase negative staphylococcus and Pseudomonas aeruginosa respectively, for 18 hours and for 2 minutes. Then it was diluted and cultured on nutrient agar plate. Colony counts were done after 18 hours. In case of 18 hours incubation, there was no growth of microbials in 0.5%, 0.1% tetracaine hydrochloride, but there was no inhibitory effect of 0.02% tetracaine hydrochloride on growth of microbials, irrespective of inoculum amount. In case of 2 minutes incubation with 0.5% tetracaine hydrochloride, there was no difference between the amount of microbial inoculum and colony count. Above indicates that tetracaine hydrochloride has no inhibitory effect on bacterial growth after short exposure of less than 2 minutes.

Estudio comparativo de la acción anestésica tópica de Bupivacaína, Etidocaína y Tetracaína / Comparative study of the topical anesthetic action of Bupivacaine, Etidocaine and Tetracaine

Los anestésicos locales Bupivacaína y Etidocaína, aunque poseen una gran actividad y prolongada duración de su efecto, no tienen aplicación clínica como anestésicos de uso tópico. En esta investigación se estudia comparativamente con Tetracaína, la capacidad de estas sustancias de bloquear los impulsos sensitivos que se generan en la superficie corneal. Se utilizó el test de inhibición de reflejo corneal en el conejo, método que permite determinar tanto la duración como la intensidad del efecto anestésico tópico. Los resultados confirmaron observaciones previas y mostraron que Bupivacaína y Etidocaína bloquean la vía aferente de este reflejo con concentraciones milimolares y su actividad fue semejante a la de Tetracaína. La duración del efecto máximo (anestesia completa) varió entre 22 y 24 minutos, mientras que la depresión parcial del reflejo corneal se prolongó 80 a 100. Estos resultados sugieren que Bupivacaína y Etidocaína ejercen una potente acción anestésica sobre las superficies mucosas y por consiguiente, es necesario su estudio clínico en la mucosa bucal

Action of acetylcholine on the atropinised frog heart during the winter months.

During the winter months, high doses of acetylcholine produced positive inotropic action without any chronotropic action on the perfused atropinised frog heart, in 5 out of 24 preparations. In the remaining preparations acetylcholine failed to produce any action and positive inotropic effect of acetylcholine on these preparations was noticed if they were perfused with the medium containing excess of calcium. However, the rate remained unchanged. The positive inotropic action was blocked by the local anaesthetic amethocaine and thus may be due to increased penetration of calcium into the cardiac cell.