A Study to Find Out if the Medicine Called Rimegepant is Safe for Adults in India

Inclusion Criteria

Participants are eligible to be included in this study only if all of the following criteria apply:

Age and Reproductive Status:

1. 18 years of age or older who meet the reproductive criteria.

   Disease Characteristics:
2. Participant has at least a 1-year history of migraine (with or without aura) consistent with a diagnosis according to the International Classification of Headache Disorders, 3rd Edition, including the following:

   1. At least 5 attacks fulfilling criteria 1-3:

      1. Headache attacks lasting 4-72 hours (when untreated or unsuccessfully treated).
      2. Headache has at least 2 of the following 4 characteristics:

         * Unilateral location
         * Pulsating quality
         * Moderate or severe pain intensity
         * Aggravation by or causing avoidance of routine physical activity (eg, walking or climbing stairs)
      3. During headache, at least 1 of the following:

         -Nausea and/or vomiting
         * Photophobia and phonophobia
   2. Not better accounted for by another ICHD-3 diagnosis.
3. Participants experience 4-14 migraine days / month and fewer than 7 non-migraine headache days / month on average and overall, less than 15 days with headache (migraine or non-migraine) per month across the 3 months prior to screening.
4. Participants on prophylactic migraine medication (non-CGRP) are permitted to remain on therapy if they have been on a stable dose for at least 3 months prior to screening visit, and the dose is not expected to change during the study.
5. Participants have previous insufficient response and/or prior intolerance to at least one triptan or documented contraindication to the use of triptan.

   1. Insufficient response - Previous treatment with one or more triptan has yielded no, unsatisfactory or inconsistent therapeutic effect (eg, recurrent, incomplete relief of migraine related symptoms \[including pain, nausea, photophobia, phonophobia etc\] at 2 hours post dose, non-sustained relief of migraine related symptoms through 24 hours post dose, etc), after repeated dosing (≥2 attempts) at recommended dose level.
   2. Prior intolerance - treatment with triptan has been interrupted because of an adverse event that made continuation of the drug intolerable for the individual.

      -Prior triptan associated overuse headache

      -Arrhythmia associated with prior triptan use

      -Chest/throat/neck/jaw pain, tightness, pressure or heaviness associated with prior use of triptan

      -Gastrointestinal ischemia or peripheral vasospastic reaction associated with prior use of triptan
      * Serotonin syndrome associated with prior triptan use
   3. Documented contraindication to triptans -

      1. Documented hypersensitivity to triptan
      2. Cardiovascular events, conditions and procedures considered contraindications to the use of triptan medications.

   i. Events: Myocardial infractions, prior cardiac arrest, transient ischemic attack, cerebrovascular accident (Intracerebral haemorrhage, intracranial haemorrhage, subarachnoid haemorrhage, ischemic stroke) ii. Conditions: Angina pectoris, coronary artery vasospasm, ischemic coronary artery disease, peripheral artery disease, ischemic bowel disease, cardiac conduction disorders (life threatening arrhythmia/heart block) iii. Procedure: Angioplasty, coronary artery bypass grafting, carotid endarterectomy 3) Uncontrolled hypertension

Exclusion Criteria

Participants are excluded from the study if any of the following criteria apply:

Medical Conditions:

1. Any medical or psychiatric condition including any active suicidal ideation in the past year or suicidal behavior in the past 5 years or laboratory abnormality that may increase the risk of study participation or, in the investigator's judgment, make the participant inappropriate for the study.

   * PHQ-8 total score ≥15
   * Suicidal ideation and behavior (one, or more, of the below is exclusionary):

     * a positive response to item 1 or 2 of the C-SSRS within 30 days prior to Screening;
     * suicidal ideation associated with actual intent and/or a method or plan at any time in their lifetime: any positive response on items 3, 4 or 5 of the C-SSRS;
     * any previous lifetime history of suicidal behavior: "Yes" to answer to any of the suicidal behavior items of the C-SSRS.
   * Current diagnosis of schizophrenia, bipolar, or borderline personality disorder.
   * History of severe drug allergy, including anaphylaxis or known hypersensitivity or intolerance to rimegepant or any of its excipients.
2. Any of the following:

   * History of any trigeminal autonomic cephalalgia (eg. cluster headache, Short-lasting, Unilateral, Neuralgiform headache attacks with Conjunctival injection and Tearing \[SUNCT\], Short-lasting unilateral neuralgiform headache attacks with cranial autonomic symptoms \[SUNA\], hemicrania continua, paroxysmal hemicrania).
   * Active chronic pain syndrome (such as fibromyalgia, chronic pelvic pain, complex regional pain syndrome \[CRPS\]); Other pain syndromes (including trigeminal neuralgia), dementia, or significant neurological disorders (other than migraine) that, in the Investigator's opinion, interfere with study assessments of safety.

   Prior/Concomitant Therapy:
3. Current use of any prohibited concomitant medication(s).
4. History of use of ergotamine medications or triptans for greater than/equal to 10 days per month on a regular basis for greater than/equal to 3 months, or history of non-narcotic analgesic intake for greater than/equal to 15 days per month for greater than/equal to 3 months (eg, acetaminophen, non-steroidal anti-inflammatory drugs \[NSAIDs\], gabapentin) for other pain indications.

   Prior/Concurrent Clinical Study Experience:
5. Participation in clinical trial with non-biological investigational agents or interventional treatments (last study visit occurring) within the 30 days or 5 half-lives of investigational drug (whichever is longer) prior to Baseline Visit. Participation in clinical trial with biological investigational agents (last study visit occurring) within 90 days or 5 half-lives (whichever is longer) prior to Baseline Visit. Participation in any other investigational clinical trial while participating in this clinical trial.

   Diagnostic Assessments:
6. ANY of the following findings at the Screening Visit and laboratory tests as assessed by the study-specific laboratory:

   * eGFR (using CKD-EPI-Scr-Scys Combined) \<30 mL/min/1.73m²
   * Total bilirubin \>1.5 × ULN (may be repeated once, with fractionation, for confirmation during the Screening Phase, and direct bilirubin \>ULN is exclusionary if Gilbert's syndrome is suspected)
   * AST (SGOT) or ALT (SGPT) \>2.0 × ULN

   Other Exclusion Criteria:
7. Investigator site staff directly involved in the conduct of the study and their family members, site staff otherwise supervised by the investigator, and sponsor and sponsor delegate employees directly involved in the conduct of the study and their family members.