Topical Gabapentin Amitriptyline and Lignocaine (ToGA) ointment trial for post­haemorrhoidectomy analgesia

Treating team or surgeon will perform initial assessment of patients with grade III or IV haemorrhoids referred from the community by their general practitioner or through the emergency department. They will then indicate the suitability of patients for a formal haemorrhoidectomy. Patients will receive a standard surgical treatment for management of grade III or IV haemorrhoids, after verbal and written informed consent performed by the consultant surgeon of the unit, or the treating surgical registrar after consultation with the on-call surgeon. On the day of surgery, patients will undergo standardised general anaesthesia by Monash Health anaesthetic unit prior to surgical procedure, along with associated standard monitoring. Patients will be placed in the lithotomy position to undergo formal Milligan-Morgan or Ferguson haemorrhoidectomy using diathermy. Our routine immediate post-operative analgesia includes performing a bilateral pudendal nerve block. We use 20 ml of a 0.75% Ropivacaine solution for the pudendal block. This is infiltrated first superficially under the skin and then deeper along the submucosa and intramuscular spaces into all four quadrants. In the post-anaesthesia care unit (PACU), VAS (Numerical pain scoring system between 0 – 10) will be assessed by nursing staff, and recorded. Rescue opioid pro re nata will be provided. Post-operative analgesic regimen will comprise of oral Paracetamol 1g every 6 hours, and opioid analgesia pro re nata will be provided for patients in the ward. All patients will also receive the conventional oral metronidazole 400mg thrice daily for five days, stool softeners, and smear of glyceryl trinitrate ointment thrice daily. Daily measurement of additional pro re nata opioid required will be recorded. Participants requiring opioid analgesia as inpatient, would also be discharged on oral opioid, and be required to document the number of tablets of oral opioid they require per day, in their pain diary. A biostatistician will prepare a computer-generated randomisation schedule using random permuted blocks, in order to allocate the 166 study medications (and also study participants) to either Group A or B. The first group (A) — will receive the compound topical Gabapentin, Amitriptyline and Lignocaine ointment, and the second group (B)— will receive topical placebo ointment, made up of paraffin. The proposed topical ointment consists of: Gabapentin 6%, Amitriptyline 2%, and Lignocaine 5%. Both ointments will be produced by Department of Pharmacy, Monash Health. Both ointments will be labelled with the study number according to the randomisation allocation and dispensed by the Department of Pharmacy. Provision of labelled ointments by the pharmacy will ensure blinding of the patients and the treating team. Our ward pharmacist or member of the treating team will provide careful instructions on how to apply ointment, and monitoring of any side effects. The application of the ointment involves smearing a small amount of ointment onto patient's index finger and applying this directly onto the anus post-operative wound three times daily from day 1 post-operative for 2 weeks duration. Patients will be discharged from hospital once comfortable ambulating and showing no acute signs of urinary retention or faecal impaction as assessed by the treating team. Each patient will be provided with the Pain Diary post-op. Pain scoring will be performed and recorded by individual patients in the Pain Diary at post-operative day 1, 3, 7 and finally at 2 weeks outpatient follow-up.