Plasma Concentration of Ketamine and Norketamine .
Condition: Chronic Pain
MeSH terms: Chronic Pain
Study type: Interventional

Summary: 
      Oral ketamine is increasingly used by doctors to both reduce the amount of narcotic pain
      medication consumed and to improve chronic pain management in difficult cases. How much is
      absorbed when taken orally, as opposed to intravenously ,is unknown. Ketamine may cause
      sedation, and occasionally cognitive impairment. Therefore, there are safety concerns
      associated with its usage as an out-patient may engage in activities where cognitive
      impairment is dangerous,such as driving. This study is designed to measure the plasma
      concentrations of ketamine and its active metabolite, norketamine, in people taking low dose
      oral ketamine for chronic pain. The goal of the study is to verify that low dose oral
      ketamine produces plasma concentrations below the level associated with toxic symptoms,and
      thus can be safely used long-term for the treatment of chronic pain .
    

Detailed description: 
      This is a non-randomized, cohort study to measure the serum uptake of low dose oral ketamine
      in chronic pain patients. The SJHC pharmacy has a list of patients to whom they dispense oral
      ketamine. We plan to recruit fifteen patients from this patient group.

      This is a pilot study and very little information is available to help with sample size
      calculations. We also plan to measure change in mean pain score from Day to Day 14 using the
      Brief Pain Inventory (BPI) This data will aid the design and calculation of sample size in
      future studies. Study Design: Days 1-7: Following informed consent, the patient's demographic
      information and initial assessment will be completed on Day 1 at the first visit. They will
      be allowed to continue all usual systemic analgesic medications. They will be given
      instructions on how to take the study medication and will be given a list of foods that could
      possibly induce or inhibit the enzyme, Cyp3A4 or Cyp2B6 (i.e. grapefruit or grapefruit
      juice). Subjects will be given a 7 day supply of 10 mg ketamine tablets. The patients will be
      instructed to take one ketamine tablet three times per day at specified times for seven days
      and to return to clinic on Day 7. They will be instructed not to take their morning dose of
      ketamine and to eat a light breakfast on Day 7. Upon arrival, the patients will complete the
      Brief Pain Inventory and side effects questionnaire. The patient will have a 20 gauge (saline
      locked) IV started in the antecubital fossa to allow for five blood samples: Time Zero, 30,
      60, 90 and 120 minutes. The first blood sample at Time 0 will be obtained just before the
      patient takes his/her oral dose of ketamine (trough concentration). The four remaining
      samples will be taken after the patient ingests his/her 10 mg ketamine dose. Time Activity
      Arrival Complete BPI, side effect questionnaire Time Zero Blood draw, then take 10mg oral
      ketamine dose 30 minutes post ingestion Blood draw 60 minutes post ingestion Blood draw 90
      minutes post ingestion Blood draw 120 minutes post-ingestion Blood Draw Days 8-14: The
      subjects will be given a supply of 20 mg ketamine capsules and instructed to take them three
      times per day, at specified times, and to return to clinic on Day 14. The instructions and
      procedures at the second clinic visit will be the same as on Day 7.
    

Intervention name(s): Ketamine
Intervention type(s): Drug
Intervention description(s): The St.Joseph's Heath Care Pharmacy will supply the compounded oral ketamine capsules. Patients who are going to participate in this study are already taking this oral ketamine as a part of their chronic pain medications. No new patient will start oral ketamine for the sake of this study. Two doses of oral ketamine will be used for the same patient, 10 mg and 20 mg every 8 hours. These doses are the standard doses in our clinic. Other clinics using much higher doses.
Intervention MeSH terms: Ketamine
Intervention model: Single Group Assignment
Masking: None (Open Label)
Keywords: Chronic Pain, Ketamine, Safety