The Experts below are selected from a list of 42 Experts worldwide ranked by ideXlab platform
Stephen T. Gancher - One of the best experts on this subject based on the ideXlab platform.
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Effect of Long-term Therapy on the Pharmacodynamics of Levodopa: Relation to on-off Phenomenon
Archives of neurology, 1992Co-Authors: John G. Nutt, William R. Woodward, Julie H. Carter, Stephen T. GancherAbstract:To determine how the response to levodopa is altered by long-term therapy, we examined the dose response to 2-hour infusions of levodopa in three groups of parkinsonian patients: those who were previously untreated, those who exhibited stable responses, and those who exhibited fluctuating responses to levodopa therapy, using tapping speed as an index of bradykinesia. The baseline tapping speed was greater in the patients with stable responses than in the untreated patients, probably representing a "long-duration response" to levodopa therapy. A "short-duration response," indicated by an increase in tapping speed lasting hours, was observed in most patients in all groups. The onset of the short-duration effect was more rapid and the incremental increase in tapping speed was twice as large in the patients with fluctuating responses compared with the untreated patients and patients with stable responses. The duration of the short-duration effect was greatest in the untreated group but did not differ between the groups with stable and fluctuating responses. Dyskinesia was not observed in any of the de novo patients but was observed in three of 12 patients with stable responses and eight of nine patients with fluctuating responses to levodopa therapy. Dyskinesia appeared before or with the antiparkinsonian effects in patients with stable responses, giving no indication of a higher threshold for dyskinesia in these patients compared with those with fluctuating responses. The plasma half-life clearance, volume of distribution, and maximum plasma concentrations of levodopa did not differ among groups.(ABSTRACT TRUNCATED AT 250 WORDS)
John G. Nutt - One of the best experts on this subject based on the ideXlab platform.
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Effect of Long-term Therapy on the Pharmacodynamics of Levodopa: Relation to on-off Phenomenon
Archives of neurology, 1992Co-Authors: John G. Nutt, William R. Woodward, Julie H. Carter, Stephen T. GancherAbstract:To determine how the response to levodopa is altered by long-term therapy, we examined the dose response to 2-hour infusions of levodopa in three groups of parkinsonian patients: those who were previously untreated, those who exhibited stable responses, and those who exhibited fluctuating responses to levodopa therapy, using tapping speed as an index of bradykinesia. The baseline tapping speed was greater in the patients with stable responses than in the untreated patients, probably representing a "long-duration response" to levodopa therapy. A "short-duration response," indicated by an increase in tapping speed lasting hours, was observed in most patients in all groups. The onset of the short-duration effect was more rapid and the incremental increase in tapping speed was twice as large in the patients with fluctuating responses compared with the untreated patients and patients with stable responses. The duration of the short-duration effect was greatest in the untreated group but did not differ between the groups with stable and fluctuating responses. Dyskinesia was not observed in any of the de novo patients but was observed in three of 12 patients with stable responses and eight of nine patients with fluctuating responses to levodopa therapy. Dyskinesia appeared before or with the antiparkinsonian effects in patients with stable responses, giving no indication of a higher threshold for dyskinesia in these patients compared with those with fluctuating responses. The plasma half-life clearance, volume of distribution, and maximum plasma concentrations of levodopa did not differ among groups.(ABSTRACT TRUNCATED AT 250 WORDS)
Julie H. Carter - One of the best experts on this subject based on the ideXlab platform.
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Effect of Long-term Therapy on the Pharmacodynamics of Levodopa: Relation to on-off Phenomenon
Archives of neurology, 1992Co-Authors: John G. Nutt, William R. Woodward, Julie H. Carter, Stephen T. GancherAbstract:To determine how the response to levodopa is altered by long-term therapy, we examined the dose response to 2-hour infusions of levodopa in three groups of parkinsonian patients: those who were previously untreated, those who exhibited stable responses, and those who exhibited fluctuating responses to levodopa therapy, using tapping speed as an index of bradykinesia. The baseline tapping speed was greater in the patients with stable responses than in the untreated patients, probably representing a "long-duration response" to levodopa therapy. A "short-duration response," indicated by an increase in tapping speed lasting hours, was observed in most patients in all groups. The onset of the short-duration effect was more rapid and the incremental increase in tapping speed was twice as large in the patients with fluctuating responses compared with the untreated patients and patients with stable responses. The duration of the short-duration effect was greatest in the untreated group but did not differ between the groups with stable and fluctuating responses. Dyskinesia was not observed in any of the de novo patients but was observed in three of 12 patients with stable responses and eight of nine patients with fluctuating responses to levodopa therapy. Dyskinesia appeared before or with the antiparkinsonian effects in patients with stable responses, giving no indication of a higher threshold for dyskinesia in these patients compared with those with fluctuating responses. The plasma half-life clearance, volume of distribution, and maximum plasma concentrations of levodopa did not differ among groups.(ABSTRACT TRUNCATED AT 250 WORDS)
William R. Woodward - One of the best experts on this subject based on the ideXlab platform.
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Effect of Long-term Therapy on the Pharmacodynamics of Levodopa: Relation to on-off Phenomenon
Archives of neurology, 1992Co-Authors: John G. Nutt, William R. Woodward, Julie H. Carter, Stephen T. GancherAbstract:To determine how the response to levodopa is altered by long-term therapy, we examined the dose response to 2-hour infusions of levodopa in three groups of parkinsonian patients: those who were previously untreated, those who exhibited stable responses, and those who exhibited fluctuating responses to levodopa therapy, using tapping speed as an index of bradykinesia. The baseline tapping speed was greater in the patients with stable responses than in the untreated patients, probably representing a "long-duration response" to levodopa therapy. A "short-duration response," indicated by an increase in tapping speed lasting hours, was observed in most patients in all groups. The onset of the short-duration effect was more rapid and the incremental increase in tapping speed was twice as large in the patients with fluctuating responses compared with the untreated patients and patients with stable responses. The duration of the short-duration effect was greatest in the untreated group but did not differ between the groups with stable and fluctuating responses. Dyskinesia was not observed in any of the de novo patients but was observed in three of 12 patients with stable responses and eight of nine patients with fluctuating responses to levodopa therapy. Dyskinesia appeared before or with the antiparkinsonian effects in patients with stable responses, giving no indication of a higher threshold for dyskinesia in these patients compared with those with fluctuating responses. The plasma half-life clearance, volume of distribution, and maximum plasma concentrations of levodopa did not differ among groups.(ABSTRACT TRUNCATED AT 250 WORDS)
Steven Dubovsky - One of the best experts on this subject based on the ideXlab platform.
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Oxcarbazepine-induced reversible anorgasmia and ejaculatory failure: a case report.
The Primary Care Companion to The Journal of Clinical Psychiatry, 2009Co-Authors: Kamaljeet Boora, Kimberley Chiappone, Steven DubovskyAbstract:To the Editor: Psychotropic drugs are well known to affect sexual functioning1 and may contribute to patient noncompliance. The serotonin reuptake inhibitor antidepressants are particularly known for their effects on orgasm.2 Much less is known about adverse sexual effects of anticonvulsants, although a few case reports suggest that topiramate,3 gabapentin,4 and carbamazepine5 may cause ejaculatory failure, though these cases are mainly from patient populations with epilepsy. Here, we report a case of oxcarbazepine-induced anorgasmia and ejaculatory failure in a patient with schizoaffective disorder. Case report. Mr A, a 28-year-old man, has a long history of DSM-IV schizoaffective disorder. Upon his initial presentation to the outpatient mental health clinic in 2008, he was being prescribed quetiapine 600 mg/d and paliperidone 6 mg/d. Despite this, he remained preoccupied by paranoid delusions and complained of feeling depressed and hopeless with neurovegetative symptoms, sleep disturbance, and severe anxiety. Though he endorsed intermittent passive death wishes, he denied suicidal thoughts, intent, or plan to harm himself or others. His history revealed episodic increased energy, decreased need for sleep, increased goal-directed activities, disorganized behavior, and worsening psychotic symptoms that seemed consistent with mania. To better control the psychotic symptoms, Mr A's paliperidone was increased to 9 mg/d. At his next appointment, Mr A felt his psychotic symptoms were largely under control with the paliperidone and the quetiapine but continued to complain of low mood, anxiety, sleep disturbance, and low energy. It was recommended that Mr A undergo a trial with a mood stabilizer. Mr A initially refused to take lithium, valproic acid, or carbamazepine, as he did not want to undergo the laboratory work required to monitor the blood levels of these drugs. However, he was agreeable to a trial of oxcarbazepine 300 mg PO bid, despite the fact that this medication would still require occasional laboratory work. Within a week, Mr A felt that his mood had improved, but he complained of concerning sexual side effects, specifically an inability to experience orgasm or ejaculate. He denied having cloudy urine after sexual activity, making retrograde ejaculation less likely. Neither libido nor erection was affected. Mr A stopped oxcarbazepine treatment due to these concerns, and within a few days the sexual side effects abated. After a few days, he resumed oxcarbazepine 300 mg twice daily. Again, he experienced anorgasmia and ejaculatory failure. Due to these symptoms, which Mr A found intolerable, oxcarbazepine treatment was stopped at the next visit. At the following appointment, orgasm and ejaculatory abilities had returned to normal. During this time period, Mr A denied taking any illicit drugs or any alcohol abuse, and no other new medications had been initiated. This case demonstrated a clear on/off phenomenon of anorgasmia and ejaculatory failure related to oxcarbazepine. We have found no previous reports of anorgasmia and ejaculatory failure associated with oxcarbazepine, although it has been associated with sexual side effects. In a study of its use in epilepsy, 17% of men reported sexual dysfunction.6 Anticonvulsant medications may interact with sex hormones,6 and central-acting drugs such as oxcarbazepine may cause anorgasmia in conjunction with sedation. It is difficult to determine a mechanism by which oxcarbazepine (keto analogue of carbamazepine with no significant anticholinergic or sympatholytic activity) could cause ejaculatory failure, but its use should be reconsidered if troublesome ejaculatory failure develops. We usually ask questions about decreased sexual function with selective serotonin reuptake inhibitors, but not with anticonvulsants. Physicians should be vigilant and should evaluate patients for sexual dysfunction with anticonvulsant treatment.
