Allergy, sensitivity, or absolute contraindications to any of the medications involved in the study
preexisting CNS depression, or taking regularly medication that cause CNS depression
preexisting cognitive deficits, dementia, or delirium
severe respiratory comorbidities (e.g. chronic obstructive pulmonary disease, pneumonia, respiratory failure)
sleep disordered breathing (diagnosed OSA, obesity hypoventilation syndrome)
pregnancy and breast feeding
history of chronic pain or regular (at least once daily) opioid use preoperatively
renal impairment - CrCl =60 mL/minute
not fluent in English to be able to participate in the study process, including consent and phone interview
Body Mass Index >35
inability to take oral medication.

NCT02939209_exc_T1
Condition
Allergy
NCT02939209_exc_T2
Condition
sensitivity
NCT02939209_exc_T3
Condition
contraindications
NCT02939209_exc_T4
Drug
medications
NCT02939209_exc_T5
Qualifier
study
NCT02939209_exc_T6
Scope
Allergy, sensitivity, or absolute contraindications
NCT02939209_exc_T7
Condition
CNS depression
NCT02939209_exc_T8
Drug
medication
NCT02939209_exc_T9
Condition
CNS depression
NCT02939209_exc_T10
Condition
cognitive deficits
NCT02939209_exc_T11
Condition
dementia
NCT02939209_exc_T12
Condition
delirium
NCT02939209_exc_T13
Condition
respiratory comorbidities
NCT02939209_exc_T14
Qualifier
severe
NCT02939209_exc_T15
Condition
chronic obstructive pulmonary disease
NCT02939209_exc_T16
Condition
pneumonia
NCT02939209_exc_T17
Condition
respiratory failure
NCT02939209_exc_T18
Scope
chronic obstructive pulmonary disease, pneumonia, respiratory failure
NCT02939209_exc_T19
Condition
sleep disordered breathing
NCT02939209_exc_T20
Condition
OSA
NCT02939209_exc_T21
Condition
obesity hypoventilation syndrome
NCT02939209_exc_T22
Scope
OSA, obesity hypoventilation syndrome
NCT02939209_exc_T24
Condition
chronic pain
NCT02939209_exc_T25
Drug
opioid
NCT02939209_exc_T26
Multiplier
at least once daily
NCT02939209_exc_T27
Qualifier
preoperatively
NCT02939209_exc_T28
Condition
renal impairment
NCT02939209_exc_T29
Measurement
CrCl
NCT02939209_exc_T30
Value
=60 mL/minute
NCT02939209_exc_T32
Measurement
Body Mass Index
NCT02939209_exc_T33
Value
>35
NCT02939209_exc_T34
Mood
inability
NCT02939209_exc_T35
Drug
oral medication