Clinical Trial Exploring the Outpatient Treatment of Phantom Limb Pain With Ketamine Administration in a Six Month Study With a Minimum Remission Period of 7 Days Between Treatment Session. 25-30 Subjects With an Ongoing History of Significant PLP.--FDA and IRB Approved.

Inclusion Criteria:

• Presence of phantom limb pain at the time of administration of ketamine.

• Willingness to participate in the study and follow-up over a year long period.Living Within a 50 mile radius of our study sites: Bay Area, Los Angeles,Albuquerque, Sacramento, Los Angeles

• Provision of signed and dated, written informed consent prior to any study-specificprocedures.

• If female, must have a negative pregnancy test at Screening and any subsequentadministration of ketamine. Sexually active females and male partners must be usingadequate birth control measures during the duration of the study when ketamine willbe administered and for one week after the last administration of ketamine.

• Patient agrees to withhold alcohol, marijuana, nicotine products, and any otherintoxicants for at least 24 hours

• Normotensive-defined as Abnormal VS, after 5 minutes supine rest at Screening or onDay -1, defined as any of the following:

Systolic BP> 150 mmHg.

• Diastolic BP> 105 mmHg.

• HR <50 or >110 bpm.

• Not on Medications that would blunt ketamine's effects

• 18-65

• No prior history of treatment with ketamine for PLP.

Exclusion Criteria:

Exclusion Criteria

• History of any clinically important disease or disorder which, in the opinion of theInvestigator, may either put the patient at risk because of participation in thestudy, or influence the results or the patient's ability to participate in thestudy.

• Vulnerable persons are Excluded from the study. This includes subjects with knownpsychotic illness, mania, significant neurologic disorders, elevated intraocular andor intracranial pressures

• Exclusion of subjects with abnormal baseline hepatic and renal lab tests.

• Exclusion of subjects with cardiovascular disease, arrythmias, or abnormal EKGs.

• The presence of any medication that might cause an adverse reaction with ketamine.

• The Ketalar Label as cited by FDA includes Drug Interactions particular toanesthesia and the use of IV boluses at far higher dosages than those used in ourstudy. In Review of these:

Theophylline Or Aminophyline --Excluded

• Sympathomimetics And Vasopressin-Excluded

• Benzodiazepines-PLP patients may be on benzodiazepines or other anxiolyticmedications, Subjects will be asked to suspend daytime use of these wheneverpossible recognizing that anxiety is an often present symptom within the PLPcomplex. Recognition of a possible increase in sedation due to the concomitantpresence of a benzodiazepine with ketamine may lead to a lowering of the ketaminedosage. Nighttime use of a benzodiazepine for treatment of insomnia will not bediscontinued unless the dosage is high and considered to have a sedating effect onthe degree of ketamine's sedation the next day. The length of time between nighttimeuse and administration of ketamine during the day should diminish the effects of thenighttime medication.

• Opioid Analgesics -PLP subjects most likely will have been or will be receivingopiates for pain relief, Concomitant use of ketamine and opiates in outpatientsettings for analgesia is a common and accepted practice. Withdrawing opiates forketamine administered in subanesthetic doses is not appropriate. In several studiesketamine has been shown to reduce the amount of opioids needed for analgesia, It isthe hope of this study that successful treatment with ketamine will enable reductionor cessation of opioid use, In our vast clinical experience, we have treated withketamine at subanesthetic doses patients on opiates without adverse effects.

• Subjects on long-acting opioids such as methadone or extended-release opioids areexcluded.

• Subjects with opioid use 50 mg/day MME (morphine milliequivalents) within 1 week ofinitial ketamine administration are excluded.

• Subjects with +UDS (urine drug screen) for ketamine, cocaine, methamphetamine, PCP,or other substances of abuse are excluded.

• Subjects who have used THC may be enrolled but must have abstained from THC for atleast 3 days prior to each ketamine session

Concomitant medications:

• Oral IR (immediate release) opioid mu agonists up to 50 mg/day MME (morphinemilliequivalents) are allowed (e.g., hydromorphone, oxycodone, morphine, andhydrocodone).

• No increases of any opioids or other concomitant medications, or addition of newmedications or therapies for PLP will be allowed during the study.

• All concomitant medications, including type and amount, will be recorded by studyparticipants in their daily diaries and reviewed by study staff before eachtreatment session and any scheduled telephone calls.

• Participants will not receive opioids 4 hours before or after ketamineadministration.

• Laboratory assessments: Subjects with abnormal baseline hepatic or renal lab testsare to be excluded. In addition, obtain the following laboratory tests at thefollowing times: CBC, hepatic and renal labs at 3 months and 6 months. Follow-upabnormal laboratory values.

• Or Other CNS Depressants-gabapentin may well be prescribed for patients with PLP asis true for pregabalin, Whenever possible subjects will be asked to withhold thesefor at least 4 hours prior and not resume for at least 4 hours after the lastadministration of ketamine. This is consistent with two half-lives of ketamine

• Alcohol-Daily use exceeding 2 US Standard drinks. No alcohol use in 24 hourspreceding a ketamine session.

• Stimulants-Subjects will be asked to withhold stimulants for 5-12 hours prior toadministration of ketamine depending on the duration of action of the particularpreparation and not resume until the next day after treatment.

Inclusion Criteria: