Guthrie Stuart, Jensen Thomas, Hartley Richard C, Ramaesh Kanna, Lockington David
Tennent Institute of Ophthalmology, Gartnavel General Hospital, 1053 Great Western Road, Glasgow, G12 0YN, UK.
WestCHEM School of Chemistry, University of Glasgow, Glasgow, G12 8QQ, UK.
Eye (Lond). 2018 Oct;32(10):1615-1620. doi: 10.1038/s41433-018-0143-y. Epub 2018 Jun 15.
Unpreserved phenylephrine is often used as an off-licence intracameral surgical adjunct during cataract surgery to assist with pupil dilation and/or stabilise the iris in floppy iris syndrome. It can be delivered as a neat 0.2 ml bolus of either 2.5 or 10% strength, or in a range of ad-hoc dilutions. We wished to assess the accuracy of intracameral phenylephrine preparation in clinical practice.
Phenylephrine 0.2 ml was analysed both neat (2.5 and 10%) and in diluted form (ratio of 1:1 and 1:3). Samples were analysed using the validated spectrophotometric method.
A total of 36 samples were analysed. The standard curve showed linearity for phenylephrine (R = 0.99). Wide variability was observed across all dilution groups. There was evidence of significant differences in the percentage deviations from intended results between dilutions (p < 0.001). Mean percentage deviation for 1:3 dilution was significantly greater than neat (p = 0.003) and 1:1 dilution (p = 0.001). There was no evidence of a significant difference between 1:1 and neat (p = 0.827).
Current ad-hoc dilution methods used to prepare intracameral phenylephrine are inaccurate and highly variable. Small volume 1 ml syringes should not be used for mixing or dilution of drug. Commercial intracameral phenylephrine products would address dosage concerns and could improve surgical outcomes in cases of poor pupil dilation and/or floppy iris syndrome.
未保存的去氧肾上腺素常作为白内障手术中的一种超适应证前房内手术辅助药物，用于在虹膜松弛综合征中辅助瞳孔扩张和/或稳定虹膜。它可以以2.5%或10%浓度的0.2毫升原液推注形式给药，或以一系列临时稀释液的形式给药。我们希望评估临床实践中前房内去氧肾上腺素制剂的准确性。
对0.2毫升去氧肾上腺素进行原液（2.5%和10%）和稀释形式（1:1和1:3比例）分析。使用经过验证的分光光度法对样品进行分析。
共分析了36个样品。标准曲线显示去氧肾上腺素具有线性关系（R = 0.99）。在所有稀释组中观察到广泛的变异性。有证据表明各稀释液与预期结果的百分比偏差存在显著差异（p < 0.001）。1:3稀释的平均百分比偏差显著大于原液（p = 0.003）和1:1稀释（p = 0.001）。没有证据表明1:1稀释和原液之间存在显著差异（p = 0.827）。
目前用于制备前房内去氧肾上腺素的临时稀释方法不准确且高度可变。不应使用1毫升小容量注射器进行药物混合或稀释。商业化的前房内去氧肾上腺素产品将解决剂量问题，并可改善瞳孔扩张不良和/或虹膜松弛综合征病例的手术效果。
