LETTERS TO EDITOR
Successful high dose of naltrexone on pediatric self-injury
Uso de naltrexona en dosis elevadas para el tratamiento de la autoagresividad en niños
Dear editor:
Naltrexone is a long acting opioid antagonist that has been used to treat self-injurious behavior (SIB) based on hypotheses that abnormal opioid systems mediate such behavior.1 Both positive and negative reports of naltrexone's efficacy can be found in the literature. We present a case with severe SIB who showed remarkable improvement on high dose naltrexone (3 mg/kg).
CASE
An autistic 8 year-old male with Down's syndrome and unspecified mental retardation was treated for SIB. SIB included head banging, skin picking, punches to head, eyes, mouth and face, hand biting, eye poking. These caused multiple visits to emergency rooms, scheduled tooth extractions, and use of a helmet. He also displayed aggression, poor socialization, and repetitive behavior. His previous pharmacologic interventions included guanfacine, citalopram, buspirone, mirtazapine, and risperidone without response. He was on risperidone 0.75 mg daily and naltrexone was initiated at a dose of 12.5 mg twice a day (0.85 mg/kg). Two weeks later his SIB had decreased, sleep improved and mood stabilized. His attention was increased and he seemed to be happier. One month later, at this dose the patient showed an increase in communicative language by the use of several signs and using words like "sorry" in an appropriate context. However, he experienced worsening of head banging, self-biting, skin picking, and eye poking. Therefore naltrexone was titrated up to 50 mg in the morning and 12.5 mg in the afternoon (2.62 mg/kg). Nevertheless, during the following 2 weeks head banging and skin picking worsened. The dose was increased to 50mg twice a day (3.50 mg/kg). After two weeks, the frequency of SIB had decreased. His attention, alertness and use of signs improved. He displayed increased interaction with family members and the treatment team. He improved his compliance with parental commands. The parents reported that he was calmer, happier, and able to sit and watch children's videos without constant re-direction. No liver function abnormalities, seizures, or side effects occurred.
DISCUSSION
The dose used on this patient is far above the consensus dose of 0.5mg/kg to 2mg/kg. However, several studies support positive responders to naltrexone having a higher baseline of SIB2 and higher doses may be more helpful in subjects with severe SIB.3 Therefore, the severity and dangerous nature of his SIB demanded rapid attenuation. Interestingly naltrexone blocks mu receptors, but at high doses blocks kappa receptors as well. Kappa agonists induce analgesia, but produce dysphoria4 rather than euphoria, and are negatively rather than positively reinforcing. In summary, naltrexone may be beneficial in a subset of SIB patients who engage in severe SIB.
REFERENCES
1. Schroeder SR, Reese RM, Hellings J, et al. The causes of self-injurious behavior and their clinical implications. In: Wieseler NA, Hanson RH, eds. Challenging behavior of persons with mental health disorders and severe developmental disabilities. Washington, DC: American Association on Mental Retardation; 1999. pp. 65-87.
2. Sandman CA, Hetrick WP, Taylor DV, Barron JL, Touchette P, Lott I, et al. Naltrexone reduces self-injury and improves learning. Exp Clin Psychopharmacol 1993;1:242-58.
3. Thompson T, Hackenberg T, Cerutti D, Baker D, Axtel S. Opioid antagonist effects on self-injury in adults with mental retardation: response form and location as determinants of mediation effects. Am J Mental Retard 1994;99:85-102.
4. Shippenberg TS, Herz A, Spanagel R, Bals-Kubik R, Stein C. Conditioning of opioid reinforcement: neuroanatomical and neurochemical substrates. Ann N Y Acad Sci 1992;654:347-56.
Ohel Soto-Raices
Research Fellow, American Psychiatric Institute for Research and Education (APIRE), Child and Adolescent Psychiatry, University of Florida, Gainesville, Florida.
Via Santo Domingo C-37 Plaza 24
Estancia, Bayamon
00961 - Puerto Rico
Publication Dates
-
Publication in this collection
13 Sept 2005 -
Date of issue
Aug 2004
