Radiation dosimetry of N-([11C]methyl)benperidol as determined by whole-body PET imaging of primates.

PURPOSE: N-([(11)C]methyl)benperidol ([(11)C]NMB) can be used for positron emission tomography (PET) measurements of D(2)-like dopamine receptor binding in vivo. We report the absorbed radiation dosimetry of i.v.-administered (11)C-NMB, a critical step before applying this radioligand to imaging studies in humans. MATERIALS AND METHODS: Whole-body PET imaging with a CTI/Siemens ECAT 953B scanner was done in a male and a female baboon. After i.v. injection of 444-1221 MBq of (11)C-NMB, sequential images taken from the head to the pelvis were collected for 3 h. Volumes of interest (VOIs) were identified that entirely encompassed small organs (whole brain, striatum, eyes, and myocardium). Large organs (liver, lungs, kidneys, lower large intestine, and urinary bladder) were sampled by drawing representative regions within the organ volume. Time-activity curves for each VOI were extracted from the PET, and organ residence times were calculated by analytical integration of a multi-exponential fit of the time-activity curves. Human radiation doses were estimated using OLINDA/EXM 1.0 and the standard human model. RESULTS: Highest retention was observed in the blood and liver, each with total residence times of 1.5 min. The highest absorbed radiation doses were to the heart (10.5 µGy/MBq) [DOSAGE ERROR CORRECTED] and kidney (9.19 µGy/MBq), [DOSAGE ERROR CORRECTED] making these the critical organs for [(11)C]NMB. A heart absorption of 50 mGy would result from an injected dose of 4,762 MBq [(11)C]NMB. CONCLUSIONS: Thus, this study suggests that up to 4,762 MBq of [(11)C]NMB can be safely administered to human subjects for PET studies. Total body dose and effective dose for [(11)C]NMB are 2.82 µGy/MBq [DOSAGE ERROR CORRECTED] and 3.7 mSv/kBq, respectively.

[Hypothermia caused by neuroleptics. 2 case reports and review of the literature]. / Hypothermie durch Neuroleptika. Zwei kasuistische Darstellungen und Literaturübersicht.

The present paper discusses appearance and course of neuroleptic induced hypothermia of a 36 years old woman suffering from periodic catatonia and a 38 years old seriously mentally handicapped man. Analysis of clinical studies and pharmacological tests with animals about body temperature changes caused by neuroleptics yields that these may lead to hypothermia as well as hyperthermia, depending on individual disposition and dose, which is mainly a result of their effect through dopaminergic neurons of the hypothalamus, which controls thermoregulation, and of their influence on vasomotoric mechanisms of vessels of the skin. Though hyperthermic changes are more hazardous and occur more frequently hypothermia by neuroleptic agents is clinically relevant as shown by the summarizing presentation of previously released case reports: hypothermia is found at neuroleptic medicated healthy volunteers and at psychiatric patients with or without physical illness, at which hypothyreosis and impair of the brain seem to represent special risks.

[Neuroleptic malignant syndrome--a case report on diagnosis, differential diagnosis and therapy of a life threatening complication of treatment with neuroleptics]. / Das maligne neuroleptische Syndrom--ein kasuistischer Beitrag zur Diagnose, Differentialdiagnose und Therapie einer lebensbedrohlichen Komplikation der Behandlung mit Neuroleptika.

The neuroleptic malignant syndrome is a potentially lethal consequence of treatment with neuroleptics. It is possible that a patient, suffering from neuroleptic malignant syndrome now, had no such illness in the past, while being treated with neuroleptics; furthermore he may respond well to rechallenge with the original agent in the future. The malignant neuroleptic syndrome of a 29 year old man, whom we treated with benperidole, is described. The course of the disease and the differential-diagnosis is stated. The ways of treatment with bromocriptine, dantrolene sodium and amantadine, as described in the literature, are presented. As the neuroleptic malignant syndrome ist rare many cases should be collected in order to enhance the knowledge of the etiology and the pathogenesis of that life--threatening complication of treatment with neuroleptic drugs.