The analgesic efficacy of lidocaine/prilocaine cream during fine-needle aspiration biopsy of thyroid nodules

Study of the analgesic effect of lidocaine/prilocaine cream during FNA of thyroid nodule

The study has two parallel groups. It is performed using a randomized, double-blind, phase 3 method on 80 patients.

Patients who meet the entry criteria are accepted by the secretary of the ultrasound department and randomization is done by sealed cards using a block of 6 method. The professor in charge, who is not blind, will use the intervention cream or placebo for the patients. The patients will undergo FNA by the clinical assistant who is blind, and then will be asked about the amount of pain with a numerical rating scale.

In this study, 80 people who have been referred for needle biopsy of thyroid nodules for the first time with a minimum age of 18 years and a maximum age of 70 years will be included. Patients with nodules larger than one centimeter will be examined. Patients with altered mental status or inability to understand the questions, a history of long-term use of opioids or analgesics, or an allergy to the drug used in the study will be excluded.

Intervention group: lidocaine + prilocaine 5% local anesthetic cream of Tehran Chemical Pharmaceuticals in the amount of 2.5 ml (~2.5 g) will be used in a thick layer on the biopsy site of the nodule 60 minutes before the procedure. Creams will be applied to the biopsy site in a specified and equal amount by the supervisor who knows the type of cream. Control group: Placebo cream consists of a white lotion (containing lubricant and Oserin) that is similar to lidocaine/prilocaine cream and will be used in the same amount and method as local anesthetic cream.

Pain level

In this study, the permutation random block method will be used for randomization. For this purpose, a block of 6 will be used. In each block, the letter L (Lidocaine) is written on three cards, and the letter P (Placebo) is also written on three cards and is placed in a sealed envelope, the envelopes are selected randomly by Simple random sampling. The random blocks of 6 selected are as follows: PLPLLP, PPLPLL, LPPLLP, PLPLPL, LPPLLP, LPLLPP, PLLLPP, LPPLLP, PLLPPL, PPLPLL, LPLLPP, LLPLPP, LPPLLP. For example, the method of random allocation in the PLPLLP block of 6 is as follows: the first patient is assigned to treatment P, the second patient is assigned to treatment L, the third patient is assigned to treatment P, the fourth patient is assigned to treatment L, the fifth patient is assigned to treatment L, and the sixth patient is assigned to treatment P randomly.

The supervisor who is the main researcher, is responsible for giving different creams and she is not blind. A specialist clinical assistant is responsible for pain assessment and FNA procedure and he is blind. Information about the grouping of patients is not provided to the statistical analyst of the data and the study. The participants are fully informed about the procedure and the fact that they could be subject to treatment by analgesic cream or placebo cream. However, they are not aware of the type of cream used for them and this information is hidden from them.