Ketamina
DisociativosC62-(2-chlorophenyl)-2-(methylamino)cyclohexan-1-one
Estructura molecular
Datos: PubChem CID 3821 — National Library of Medicine
Efectos
Mecanismo de acción
Antagonista no competitivo del receptor NMDA de glutamato, bloqueando el canal iónico en estado abierto. También interactúa con receptores opioides, monoaminérgicos, muscarínicos, receptores sigma y canales de calcio y sodio voltaje-dependientes. El bloqueo NMDA produce anestesia disociativa, analgesia y efectos antidepresivos rápidos. La ketamina S(+) es 3-4 veces más potente que la forma R(-).
Vida media
Vida media de distribución alfa de 10-15 minutos. Vida media de eliminación beta de 2-3 horas. La norketamina (metabolito activo) tiene una vida media de 12 horas.
Toxicidad
IDENTIFICATION AND USE: Ketamine is a cyclohexanone derivative used as an anesthetic agent in human and veterinary procedures. Ketamine hydrochloride injection, USP is indicated as the sole anesthetic agent for diagnostic and surgical procedures that do not require skeletal muscle relaxation. HUMAN STUDIES: Ketamine is a unique anesthetic because it has both hypnotic and analgesic effects and also potential hallucinogenic side effects. Lack of cardiopulmonary depression makes the drug a popular choice for anesthesia in the prehospital setting. In recent years ketamine has been found to have anti-hyperalgesic and opioid saving effects, opening to new ways of managing post-operative and chronic pain states. Ketamine has been used as a drug of abuse. Ketamine produces a variety of symptoms including, but not limited to, anxiety, dysphoria, disorientation, insomnia, flashbacks, hallucinations, and psychotic episodes. Ketamine dependence and tolerance are possible following prolonged administration. A withdrawal syndrome with psychotic features has been described following discontinuation of long-term ketamine use. Frequent recreational users of ketamine have been found to have impaired memory 3 days after their last dose, compared with infrequent users. Flashbacks have also been reported. Frequent use result in tolerance and the need to increase the dose in order to maintain similar effects. Respiratory depression may occur with overdosage or too rapid a rate of administration of ketamine, in which case supportive ventilation should be employed. Mechanical support of respiration is preferred to administration of analeptics. ANIMAL STUDIES: Ketamine hydrochloride administration altered the hemogram of rhesus monkeys when compared to physical restraint for venipuncture. The alterations were decreases in the leukocyte count, total plasma proteins, and hematocrit. The decrease in the leukocyte count was due primarily to a decrease in lymphocytes with a smaller decrease in
Farmacología
Anestésico disociativo con propiedades analgésicas y antidepresivas. Aprobada como anestésico y, en forma de esketamina intranasal (Spravato), para depresión resistente al tratamiento. A dosis subanestésicas produce disociación, alteraciones perceptuales y experiencias extracorporales ('k-hole'). Riesgo de cistitis intersticial con uso crónico. Menor depresión respiratoria que otros anestésicos.
Efectos en el organismo
Farmacocinética
Vida media de distribución alfa de 10-15 minutos
IV: 1-2 minutos; IM: 5-15 minutos; Oral: 30-60 minutos
IV/IM: 1-2 horas (anestésico), efectos disociativos pueden durar 4-6 horas; Oral: 4-6 horas
IV: 30 segundos-2 minutos; IM: 3-4 minutos; Oral: 15-30 minutos
IV: 100%; IM: ~93%; Oral: ~17-20%; Nasal: ~45%
Hígado
Renal (>90% como metabolitos)
3-5 L/kg
Cronología farmacocinética
Riesgos para la salud — Calculadora de dosis
Advertencias
- Alto potencial de abuso y dependencia
- Cistitis ketamínica irreversible con uso crónico
- Deterioro cognitivo persistente
- Riesgo de accidentes por disociación
Combinaciones peligrosas
Riesgo Individual (IPRS)
Moderado
IPRS v4 · escalar normalizado [0, 1]
ModeradoModelo IPRS calculado: 20 de octubre de 2018
Fuentes de datos de dosificación
Los rangos de dosificación fueron compilados a partir de Goodman & Gilman's (14ª ed.), Rang & Dale (9ª ed.) y publicaciones indexadas en PubMed. Los valores representan promedios poblacionales para la vía de administración principal y no consideran variabilidad individual, tolerancia, peso corporal ni interacciones.