Bromocriptine Neuroleptics

DA receptors are classified as D1 to D5. Bromocriptine and pergolide act as agonists at certain subtypes, and neuroleptics such as haloperidol and thorazine act as antagonists. It is produced by several nuclei in the brain, but most notably the substantia nigra and the ventral tegmental area (VTA) of the midbrain. The substantia nigra mainly projects to the basal ganglia and the VTA supplies limbic and cortical structures. 

Neuroleptic malignant syndrome is an acute iatrogenic condition caused by neuroleptics, characterized by tremor, catatonia, fluctuating consciousness, hyperthermia, and cardiovascular instability. It is relatively uncommon, occuring in 1-1.5% of patients but is fatal in 11-38%, most often due to cardiovascular collapse (Jahan et al. 1992). The pathogenesis of neuroleptic malignant syndrome is poorly understood, but it is believed to result from altered dopamine and serotonin transmission in the hypothalamus, spinal cord, and striatum. Treatment includes discontinuation of neuroleptics and administration of drugs that increase dopamine transmission bromocriptine or L-dopa (Jahan etal. 1992 Baldessarini 1996). 

Immediate discontinuation of the antipsychotic and the use of bromocriptine when needed to manage symptoms if a neuroleptic malignant syndrome develops... 

The interpretation of the mechanism of the influence of neuroleptics on ethanol reinforcement and the appraisal of the precise role of DA is complicated by the fact that DA receptor agonists either direct (e.g. bromocriptine) or indirect (e.g. amphetamine), similarly to neuroleptics, reduce ethanol drinking (Samson et al., 1993). 

The dopamine-blocking activity of neuroleptic drugs can antagonize the effects of dopamine receptor agonists, such as bromocriptine. Conversely, bromocriptine has been reported to cause exacerbation of schizophrenic symptoms (633). 

Mueller PS, Vester JW, Fermaglich J. Neuroleptic malignant syndrome. Successful treatment with bromocriptine. JAMA 1983 249(3) 386-8. 

Frye PE, Pariser SF, Kim MH, O Shaughnessy RW. Bromocriptine associated with symptom exacerbation during neuroleptic treatment of schizoaffective schizophrenia. J din Psychiatry 1982 43(6) 252-3. 

All basic and advanced life-support measures should be implemented. Gastric decontamination should be performed. Butyrophenones are readily absorbed by activated charcoal. Aggressive supportive care should be instituted. Dystonic reactions respond well to intravenous benztropine or diphenhydramine. Oral therapy with diphenhydramine or benztropine should be continued for 2 days to prevent recurrence of the dystonic reaction. For patients suffering from neuroleptic malignant syndrome, a potentially fatal condition associated with the administration of antipsychotic drugs, dantrolene sodium, and bromocriptine have been used in conjunction with cooling and other supportive measures. Arrhythmias should be treated with lidocaine or phenytoin. Diazepam is the drug of choice for seizures phenytoin is used to prevent recurrence. Hemodialysis and hemoperfu-sion have not been shown to be effective. 

The treatment of neuroleptic malignant syndrome consists of inunediately discontinuing the neuroleptic agent and administering dantrolene sodium and dopamine-functionenhancing substances such as levodopa-carbidopa, bromocriptine, or amantadine. 

Accepted therapies include the administration of dantrolene to reduce muscle rigidity, and antiparkinson drugs such as bromocriptine and amantadine to mediate extrapyramidal symptoms. Supportive therapy is also instituted. Withdrawal of the neuroleptic drug is mandatory. 

Despite the response to dantrolene, there is no evidence of an abnormality of Ca transport in skeletal muscle with lingering neuroleptic effects, bromocriptine may be tolerated in large doses (10-40 mg/day). 

Temperature regulation problems (neuroleptic malignant syndrome [NMS], treated with dantrolene and bromocriptine)... 

---