Oral Ketamine as an Adjuvant to Oral Morphine for Neuropathic Pain in Cancer Patients

Abstract

To evaluate the role of oral ketamine as an adjuvant to oral morphine in cancer patients experiencing neuropathic pain, 9 cancer patients (5 men, 4 women) taking maximally tolerated doses of either morphine, amitriptyline, sodium valproate, or a combination of these drugs for intractable neuropathic pain, and reporting a pain score of >6 on a 0-10 scale, were studied prospectively to evaluate analgesia and adverse effects. Ketamine in the dose of 0.5 mg/kg body weight three times daily was added to the existing drug regimen. Patients were taught to maintain a pain diary wherein they daily recorded their pain, sedation, and vomiting scores, and other side effects. A decrease of more than 3 from the baseline in the average pain score, or a score of < or =3 was taken as a successful response. Seven patients exhibited a decrease of more than 3. Four patients experienced nausea, of which one had vomiting. Two developed loss of appetite. Eight patients reported drowsiness during the first two weeks of therapy (P = 0.001), and this gradually improved over the next two weeks in 5 of these 8 patients. Three patients withdrew from the study, two owing to excessive sedation and another due to a "feeling of unreality." None of the patients reported visual or auditory hallucinations. This experience suggests that low dose oral ketamine is beneficial and effective in the management of intractable neuropathic pain in patients with advanced cancer. However, its utility is limited in some patients by the adverse effects that accompany its use.

Daily Oral Ketamine for the Treatment of Depression and Anxiety in Patients Receiving Hospice Care: A 28-Day Open-Label Proof-of-Concept Trial

“…50 Significant literature supports its safe use in hospice patients for other symptoms, including pain. 36,37,40,41,[51][52][53][54][55][56] Presented are data from a 28-day, open-label, proof-ofconcept trial of daily oral ketamine administration with the objectives of evaluating and assessing the tolerability, potential efficacy, and time to potential efficacy in the treatment of depression and anxiety in patients receiving hospice care.…”

Oral Ketamine for the Rapid Treatment of Depression and Anxiety in Patients Receiving Hospice Care

“…22 Significant literature supports its safe use in hospice patients for other symptoms, including pain. [23][24][25][26][27][28][29][30][31][32] The cases presented here involved subjects in an on-going open label study that is approved by both the Institute for Palliative Medicine Institutional Review Board and the University of California, San Diego Human Research Protection Program.…”

Avaliação da S(+) cetamina por via oral associada à morfina no tratamento da dor oncológica

“…Em baixas doses, a cetamina não provoca efeitos hemodinâmicos ou depressores respiratórios, não sendo também freqüente ocorrer efeito psicomimético ou sedação 17 . Além disso, foi demonstrado que a cetamina em baixas doses é segura, sendo potente adjuvante dos opióides tanto na qualidade do alívio da dor quanto na redução da quantidade de opióide consumida 18 . O objetivo deste estudo foi avaliar a eficácia analgésica da S(+) cetamina por via oral associada ao uso de morfina no controle da dor crônica oncológica.…”

“…Entretanto, não há um consenso na literatura sobre a dose mais apropriada desse fármaco pela via oral, que tem sido usada em uma ampla faixa, com relatos de doses de 500 mg.dia -1 ou mais. Apesar dessa indefinição, muitos autores têm utilizado doses de cetamina racêmica em torno de 0,5 mg.kg -1 em algumas tomadas por dia 18,31,32 . A farmacocinética da S(+) cetamina por via oral precisa ser mais bem estudada.…”

“…Em estudo desenvolvido com pacientes portadores de dor oncológica refratária de natureza neuropática, alguns autores mostraram que o uso de 0,5 mg.kg -1 de cetamina racêmica por via oral, três vezes ao dia, associada à morfina, amitriptilina e valproato de sódio, foi capaz de reduzir os escores de dor de forma importante. Alguns pacientes tiveram sua terapêutica limitada pelos efeitos colaterais, como náu-sea e sonolência; entretanto, houve baixa incidência de efeitos psicomiméticos, que os autores atribuíram ao uso da via oral e às pequenas doses administradas 18 . Alguns estudos já haviam descrito um perfil mais favorável de efeitos colaterais com a utilização da via oral em relação à via parenteral 34 .…”