Development and validation of a reversed-phase liquid chromatographic method for the assay of lidocaine in aqueous humour samples

Determination of tamsulosin in human aqueous humor and serum by liquid chromatography–electrospray ionization tandem mass spectrometry

A simple, sensitive and selective LC-MS/MS method was developed for the determination of tamsulosin in human aqueous humor and serum to study the recently reported eye-related adverse effects of this alpha(1)-blocker drug. Aqueous humor samples were analyzed by direct injection, after addition of the internal standard, labetalol. Liquid-liquid extraction with ethyl acetate was used for serum sample preparation. The chromatographic separation was performed on a reversed phase column by gradient elution with acetonitrile -0.1% formic acid at a flow-rate of 0.2 ml/min. Detection and quantification of the analytes were carried out with a linear ion trap mass spectrometer, using positive electrospray ionization (ESI) and multiple reaction monitoring (MRM). The limit of quantification was 0.1 ng/ml for both aqueous humor and serum samples and linearity was obtained over the concentration ranges of 0.1-4.7 ng/ml and 0.1-19.3 ng/ml for aqueous humor and serum samples, respectively. Acceptable accuracy and precision were obtained for concentrations within the standard curve ranges. The method has been used for the determination of tamsulosin in aqueous humor and serum samples from patients that were on tamsulosin medication and underwent cataract surgery.

Lidocaine 2% gel versus lidocaine 4% unpreserved drops for topical anesthesia in cataract surgery: a randomized controlled trial

OBJECTIVE

To compare intracameral levels and clinical efficacy of lidocaine 2% gel with lidocaine 4% unpreserved drops.

DESIGN

Double-blind, randomized, one-surgeon, controlled trial.

PARTICIPANTS

One hundred seven consecutive cataract cases eligible for topical anesthesia.

INTERVENTION

Patients were randomly assigned to receive 20 mg of lidocaine either as lidocaine 2% gel (1 ml) or as lidocaine 4% unpreserved eyedrops (0.5 ml) before clear corneal phacoemulsification.

MAIN OUTCOME MEASURES

Aqueous samples were taken to measure lidocaine intraocular levels. Intraoperative pain was quantified a few minutes after surgery using a 0 to 10 visual analog scale.

SECONDARY OUTCOME MEASURES

Patients were asked to grade the degree to which they were bothered by tissue manipulation. The surgeon graded patients' cooperation. The anesthesiologist recorded any increase in pulse or blood pressure and the need for supplemental topical anesthesia or intravenous sedation. Duration of surgery and intraoperative complications were also recorded.

RESULTS

In the gel group intracameral lidocaine levels were significantly higher (P < 0.001) and patient-reported intraoperative pain scores were significantly lower (P = 0.026). Patients in the gel group were bothered by tissue manipulation to a lesser extent (P = 0.028), and their cooperation was better (P = 0.002). Increases in blood pressure were more frequent in the eyedrops group. Supplemental anesthesia was required in two cases (3.70%) in the gel group versus eight cases in the eyedrops group (15.09%). No correlation between intracameral lidocaine levels and intraoperative pain scores was found (r = -0.026, P = 0.789).

CONCLUSIONS

If administered by means of gel, the same amount of lidocaine gives significantly higher intracameral levels of lidocaine, better analgesia, better patient cooperation, and less need for intraoperative supplemental anesthesia. Lower pain scores do not correlate with intracameral lidocaine levels.