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  • 1
    Electronic Resource
    Electronic Resource
    Prolonged antidopaminergic actions of single doses of butyrophenones in the rat (1985)
    Springer
    Psychopharmacology 87 (1985), S. 161-166 
    Details
    ISSN: 1432-2072
    Keywords: Apomorphine ; Butyrophenones ; Dopamine receptors ; Duration of drug action ; Droperidol ; Haloperidol ; Neuroleptics ; Stereotypy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Rats were treated once with doses of haloperidol or of droperidol below and above the acute ID50 vs the dopamine agonist apomorphine; they were later challenged with an acute dose of apomorphine (0.3mg/kg, SC) and rated for stereotyped behavioral responses. The two neuroleptics were similar in acute anti-apomorphine potency (ID50=0.12 and 0.18mg/kg for haloperidol and droperidol, respectively). The antidopaminergic effects of droperidol persisted for nearly 1 week and those of haloperidol lasted for 20–40 days, depending on the dose given. The computed half-time of disappearance of their antidopaminergic effects was 7.6±1.0 days and 0.59±0.17 days for haloperidol and droperidol, respectively, following a dose of 0.3 mg/kg, and these indices of duration of action did not vary significantly at doses between 0.1 and 1.0mg/kg. Haloperidol reduced the acute entry of 3H-apomorphine into brain by 21.5% 1 week later. Treatment with apomorphine alone just prior to haloperidol (both at 0.3 mg/kg) prevented the prolonged antidopaminergic effects of the neuroleptic evaluated 1 week later. These results indicate that some neuroleptics may have very prolonged activity or retention in tissue at sites of action, even after moderate, single doses. Caution is recommended in the interpretation of studies which assume “neuroleptic-free” conditions of subjects previously exposed to a neuroleptic agent.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00431801
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  • 2
    Electronic Resource
    Electronic Resource
    Effects of maturation and aging on behavioral responses to haloperidol in the rat (1981)
    Springer
    Psychopharmacology 73 (1981), S. 219-222 
    Details
    ISSN: 1432-2072
    Keywords: Aging ; Catalepsy ; Haloperidol ; Maturation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Male Sprague-Dawley rats were evaluated between ages 18 and 825 days for responses to doses of haloperidol (0 and 0.05–10 mg/kg, IP). Catalepsy, ptosis, and inhibition of general motor activity showed steady decreases in sensitivity to the drug with age during the first 1.5 years of maturation, while rats older than 1.5 years had strikingly increased sensitivity to the activity-inhibiting and cataleptic effects of the drug. The efficacy of haloperidol on all tests in 110-day old rats was indistinguishable whether food was available continuously, or restricted to reduce body weight by 55%, indicating that the effects of maturation are due to aging and not to increasing body weight. The effects may be due to altered drug metabolism or altered sensitivity of the central nervous system to neuroleptic agents. Clinical impressions too, indicate that immature and elderly patients are more sensitive to these and other psychotropic drugs than are young adults.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00422406
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Circadian changes in behavioral effects of haloperidol in rats (1982)
    Springer
    Psychopharmacology 77 (1982), S. 150-155 
    Details
    ISSN: 1432-2072
    Keywords: Catalepsy ; Chronopharmacology ; Circadian rhythms ; Haloperidol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Circadian changes in behavioral responses to haloperidol were evaluated in rats under normal and altered lighting cycles. There was a 5.5-fold change in ED50 between the maximum (4 PM) and minimum (4 AM) cataleptic response to the drug under normal lighting (lights on 7 AM-7 PM). The rhythm was present whether the same rats were tested repeatedly, or fresh rats were used at each time to avoid drug effects which persist for at least several days. Under normal lighting, the maximum cataleptic effect of haloperidol corresponded closely to the light-phase minimum of spontaneous motor activity in untreated rats. Measures of sedation (ptosis and motor inhibition) induced by haloperidol yielded small circadian rhythms under normal lighting and were highly dependent on the baseline level of arousal. A month of constant light or dark, or reversed dark-light cycles had small effects on the sedative actions of haloperidol, although inhibition of locomotion tended to phase-shift with general arousal; these changes did not alter the catalepsy rhythm. While the circadian rhythm of spontaneous activity underwent a complete reversal within 1 month (t 1/2=17 days) of reversed lighting cycles, the catalepsy rhythm changed very gradually (t 1/2=82 days) and required nearly 6 months for complete reversal. Thus, catalepsy is a robust endogenously regulated circadian response that is only slowly influenced by altered lighting conditions which dissociate this rhythm of neuroleptic response from that of spontaneous general arousal. Endogenous neurobiologic and pharmacokinetic factors may contribute to circadian changes in neuroleptic responses.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00431938
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Differences between antipsychotic drugs in persistence of brain levels and behavioral effects (1992)
    Springer
    Psychopharmacology 108 (1992), S. 338-344 
    Details
    ISSN: 1432-2072
    Keywords: Haloperidol ; Brain levels ; Bromperidol ; Chlorpromazine ; Fluphenazine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract After a single dose of the butyrophenone neuroleptic haloperidol, behavioral effects and detectable drug levels in rat brain can last for several weeks. To determine if such persistence is a general property of neuroleptics, we compared drug levels and effects after IP administration of two butyrophenones (haloperidol and bromperidol), a high potency (fluphenazine) and a low potency (chlorpromazine) phenothiazine. Drug levels in brain tissue were measured by high pressure liquid chromatography and behavioral effects monitored as inhibition of apomorphine-induced stereotypy. Estimated near terminal elimination half-lives (t1/2) from brain for acutely administered chlorpromazine (20 mg/kg) and fluphenazine (1 mg/kg) were 0.41 and 0.62 days, respectively, and neither drug was detectable after 4 days. Fluphenazine given daily for 5 days showed an only slightly slower elimination (t1/2=1.1 days). In contrast, near-terminal elimination half-lives from brain for haloperidol and bromperidol (both at 1 mg/kg, IP) were much longer (6.6 and 5.8 days, respectively), and each was detectable for 21 days after dosing. Inhibition of apomorphine-induced stereotypy correlated highly (r=0.95) with brain levels of haloperidol. For fluphenazine, given once or repeatedly, early inhibition was replaced within 1 week by supersensitivity to apomorphine which persisted for up to 3 weeks. These findings, indicating marked differences in clearance and recovery times after dosing with butyrophenones and phenothiazines, have clear implications for studies of the effects of neuroleptic drugs in rats. While there are limits to the extrapolation of these findings to other species, our results and those from studies in human subjects suggest similarly persistent drug levels and effects may be seen when patients are withdrawn from neuroleptic drugs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02245121
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    Paper (German National Licenses)
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