Clinical trial NCT03525509: Epidural Methadone in Healthy Volunteers
Official title: Investigation of Pharmacokinetics and Pharmacodynamics of Epidural Methadone in Healthy Volunteers
Study type: INTERVENTIONAL
Overall status: COMPLETED
Phase: EARLY_PHASE1
Conditions: Pain, Acute
Keywords: Methadone
Morphine
Quantitative sensory testing
Epidural
Lead sponsor: Washington University School of Medicine
Sponsor class: OTHER
First posted: 2018-05-15
Enrollment: 13
Sex: ALL
Minimum age (years): 18
Standard ages: ADULT
OLDER_ADULT
Accepts healthy volunteers: yes
Allocation: RANDOMIZED
Intervention model: CROSSOVER
Intervention model description: Randomized, double-blinded, crossover design in healthy volunteers
Primary purpose: TREATMENT

Brief summary: Epidurally administered opioid pain medications are important tools for postoperative pain control, but each agent has its own limitations. Methadone's properties suggest that it may provide a long duration of pain control with minimal side effects related to spread to the brain or absorption into the blood stream. In this study, the investigators aim to compare the relative pain relieving effects, markers of side effects, and concentrations in the blood of epidurally administered methadone as compared to another long-acting opioid which is commonly administered epidurally, morphine.

Detailed description: Acute postoperative pain control remains a major challenge in healthcare, with a need to balance analgesic effectiveness, patient safety, and cost. Excellent analgesia is a universal clinical imperative, but our current approaches are often inadequate. Epidural opioids can be useful tools, but each carries its own strengths and limitations. Bolus morphine is long lasting but exhibits rostral spread in the cerebrospinal fluid, which raises risks of adverse effects, particularly late-onset respiratory depression. Lipophilic opioids such as fentanyl and sufentanil exhibit selective segmental analgesia but are of short duration due to systemic absorption. As such, they require continuous epidural administration via an indwelling epidural catheter and a pump (patient-controlled or continuous infusion), which has implications for nursing, pain management services, and hospital cost. Methadone's physico-chemical properties suggest that epidural methadone administration would be ideal in providing long-duration analgesia with fewer of the adverse effects seen with medications like morphine.

The aim of this study is to compare the effects of two medications given epidurally: morphine and methadone. We will do so using a randomized, double-blinded, crossover design study. During each of two study visits, participants will receive a single epidural bolus of either morphine or methadone. We will examine the ability of the medication to blunt pain from heat or pressure using quantitative sensory testing at both the dermatome of injection (leg) and a distant dermatome (face); in doing so, we will demonstrate relative segmental versus supraspinal or systemic opioid activity. Additionally, we will assess signs and symptoms of supraspinal opioid activity, which may predispose to adverse effects, and blood concentrations of each medication. Each of the aforementioned measurements will be conducted at multiple points over a 24 hour period. Following a washout period, patients will return for a second visit, at which time the protocol will be repeated using the other medication.

Eligibility criteria: Inclusion Criteria:

1. Age ≥18;
2. Body mass index between 18.5 and 30
3. Good general health with no remarkable medical conditions;
4. Able and willing to provide informed consent.

Exclusion Criteria:

1. Known history of hepatic, renal, and cardiac disease;
2. Known history of diabetes mellitus;
3. Chronic pain;
4. A skin or spine condition preventing safe epidural catheter placement;
5. Current pregnancy or lactation;
6. Known coagulopathy or ongoing anticoagulant use which contraindicates epidural catheter placement;
7. Known allergic reactions to opioids or local anesthetics;
8. History of current or prior substance use disorder or positive screen using the 4-question Simple Screening Instrument for Substance Abuse (SSI-SA).

Primary outcomes:
measure: Selective segmental analgesia for heat pain - methadone
timeFrame: 0 -12 hours after medication administration
Secondary outcomes:
measure: Selective segmental analgesia for heat pain - morphine
timeFrame: 0 -12 hours after medication administration
measure: Selective segmental analgesia for pressure pain - methadone
timeFrame: 0 - 12 hours after medication administration
measure: Selective segmental analgesia for pressure pain - morphine
timeFrame: 0 - 12 hours after medication administration
Other outcomes:
Locations:
city: Saint Louis
country: United States
facility: Washington University in St. Louis
state: Missouri
Study officials:
affiliation: Washington University in Saint Louis
name: Simon Haroutounian, PhD
role: PRINCIPAL_INVESTIGATOR
affiliation: Washington University in Saint Louis
name: Yehuda Ginosar, MBBS
role: PRINCIPAL_INVESTIGATOR
References:
citation: Shir Y, Rosen G, Zeldin A, Davidson EM. Methadone is safe for treating hospitalized patients with severe pain. Can J Anaesth. 2001 Dec;48(11):1109-13. doi: 10.1007/BF03020377.
citation: Haroutiunian S, Kagan L, Yifrach-Damari I, Davidson E, Ratz Y, Hoffman A. Enhanced antinociceptive efficacy of epidural compared with i.v. methadone in a rat model of thermal nociception. Br J Anaesth. 2014 Jan;112(1):150-8. doi: 10.1093/bja/aet234. Epub 2013 Jul 10.
citation: Bernards CM, Shen DD, Sterling ES, Adkins JE, Risler L, Phillips B, Ummenhofer W. Epidural, cerebrospinal fluid, and plasma pharmacokinetics of epidural opioids (part 1): differences among opioids. Anesthesiology. 2003 Aug;99(2):455-65. doi: 10.1097/00000542-200308000-00029.
citation: Gedney JA, Liu EH. Side-effects of epidural infusions of opioid bupivacaine mixtures. Anaesthesia. 1998 Dec;53(12):1148-55. doi: 10.1046/j.1365-2044.1998.00636.x.