Metamizole versus placebo for panretinal photocoagulation pain control: a prospective double-masked randomized controlled study

Abstract

BackgroundDiabetic retinopathy is one of most common and threatening ocular diseases. Many of these patients need to be submitted to panretinal photocoagulation (PRP), experiencing a significant level of pain. The purpose of this study is to evaluate the effectiveness of oral metamizole in reducing pain during PRP in patients with proliferative diabetic retinopathy (PDR) and very severe non-proliferative diabetic retinopathy (VSNDR).MethodsPatients from a single center with PDR or VSNDR and indication of bilateral PRP were recruited for a double-masked, controlled, prospective study. The treated eyes were randomly assigned in two groups, and each patient had one eye assigned per group. Group A received 1000 mg of metamizole and group B received a placebo pill 40 min before the laser treatment. The groups were switched for the treatment of the fellow eye. Each patient scored the pain sensation immediately after each PRP section using Scott’s visual analogue scale (VAS). The paired Student t test was used to measure the significance between the two groups VAS scores, with significance level adopted of p < 0.05.ResultsTwenty-one patients were recruited. The level of pain was significantly lower when submitted to PRP after oral metamizole treatment compared to placebo (p = 0.002). The mean pain scores for groups A and B were 4.72 ± 1.708 and 5.89 ± 1.967, respectively. The minimum/maximum scores within groups A and B were 1/8 and 1/10, respectively.ConclusionsThe use of 1000 mg of metamizole 40 min before PRP significantly reduces the pain associated with the procedure in patients with PDR or VSNDR.

Efeito analgésico da música durante a fotocoagulação retinal a laser em diabéticos: Um estudo cruzado, randomizado e controlado por placebo

“…Acute procedural pain is still a neglected phenomenon in health care (Cakmak et al, 2017;Lee, 2016;Song et al, 2018), particularly in ophthalmic procedures (Araújo et al, 2015;Castro et al, 2014;Chen et al, 2012;Chiu & Wu, 2011;Quigley et al, 2019;Ramezani et al, 2017;Santo et al, 2016). These findings corroborate our results, since most of the patients who underwent argon LRP reported pain, despite the anesthetic used, which demonstrates the nociceptive nature of the procedure.…”

“…In order for the analyses to be comparable, the technique to encircle the posterior pole of the retina (around the vascular arches) was standardized. The LRP technique in our test was standardized for bias reduction and was based on previous studies that showed no significant difference in the presence of pain in relation to the power of the laser shots provided (Araújo et al, 2015;Castro et al, 2014;Chiu & Wu, 2011;Ko, Shim, Lee, & Cho, 2009;Ramezani et al, 2017;Richardson & Waterman, 2009).…”

“…Randomized clinical trials have investigated the pharmacological management of LRP-related pain (Araújo et al, 2015;Pirelli et al, 2019;Ramezani et al, 2017;Santo et al, 2016). However, there is still little evidence to recommend the best non-pharmacological management practices for pain associated with LRP (Ribeiro, Ribeiro, Pinto, & Ribeiro, 2020).…”

Preventive Analgesia, Hemodynamic Stability, and Pain in Vitreoretinal Surgery

“…The findings in our study are contrary to the findings of some other studies evaluating the efficacy of COX-3 inhibitors on the rates of PIPP in comparison with control groups. In patients undergoing panretinal photocoagulation, intravenous infusion of 1 g of metamizole 40 min before the induction of GA resulted in a statistically significant reduction in pain perception associated with the procedure in comparison to the placebo control group [ 70 ]. The analgesic potencies of intravenous PA using paracetamol and metamizole at a dose of 1 g proved their similar efficacies for postoperative analgesia after retinal surgery in comparison to the control group [ 32 ].…”

Efficacy of Oral Alprazolam and Mefenamic Acid in Relieving Pain During Pan Retinal Photocoagulation

“…In a study conducted at Ophthalmology Service of the Hospital das Clínicas University of São Paulo Medical School by Rafael Barbosa de Araújo et al They concluded that the use of 1000 mg of Metamizole 40 minutes before PRP significantly reduced pain associated with the procedure in patients with PDR. 15 Similarly, Hazem et al in their study reported lower degree of pain associated with a better hemodynamic response in patients given 150 mg Pregabalin before photocoagulation. 16 The laser energy is focused on the retinal tissue and is absorbed by the underlying retinal pigment epithelium (RPE) and choroid.…”