A Pilot Clinical Trial of Oral Ketamine for Acute Pain Management After Amputation Surgery

Inclusion Criteria:

1. Adults of at least 18 years of age, but not older than 80 years
2. Due to undergo elective major amputation of the lower extremity (above the knee amputation (AKA), below the knee amputation (BKA), total knee amputation (TKA), transmetatarsal amputation (TMA), toe amputation) from all causes.

Exclusion Criteria:

1. Pregnancy
2. Increased intracranial pressure or intraocular pressure
3. Allergy to ketamine
4. Morbid obesity (BMI \> 40 kg/m2)
5. Significant comorbidity (ASA physical status classification \> 3)
6. Inability to communicate with the investigators
7. Any history of known or suspected drug or alcohol abuse
8. History of impaired liver function
9. Significant history of hallucinations, delusions or other psychiatric medical condition the investigator feels will prevent assessment of adverse events of study drug.
10. Significant psychiatric history; a diagnosis of schizophrenia, bipolar disorder, or severe depression.
11. Exposure to cytochrome P450 3A4 inhibitors or inducers (including grapefruit products) within 2 weeks before enrollment; the inability to avoid these products during ketamine administration.
12. Poorly-controlled hypertension