Clinical trials open studies

Gabapentin is effective as an adjunct against partial seizures and generalized tonic-clonic seizures at dosages that range up to 2400 mg/d in controlled clinical trials. Open follow-on studies permitted... 

There is much controversy over the use of open or open-label studies. It is a golden rule of clinical trial design that, wherever practicable and possible, open studies should not be conducted, but there are circumstances when they can or must be used (see Box 6.2). 

Clinical trials are sometimes continued for an open extension period. This is permissible, provided there are genuine scientific reasons for continuing the study (rather than commercial reasons, such as attempting to create demand for the product) and that the appropriate regulatory clearance has been obtained. If the company does not wish to do this, it would be open to the doctor to request further supplies of the product, but the company must not invite him to do this. Any further supply to the doctor would then need to comply with the provisions regarding particular patient supply, unless the doctor has decided to carry out his own clinical trial. 

Ad.TNF gene therapy is presently in clinical trials in patients receiving radiotherapy. An open-label, phase I, dose-escalation study of tumor necrosis factor-alpha (TNFerade) gene transfer with radiation therapy for locally advanced, recurrent, or metastatic solid tumors is currently accruing patients and has several endpoints (82), including toxicity and tolerable dose. Pharmacokinetics will be evaluated and biological correlates will determine the histologic response to therapy. 

As with carbamazepine, the historical use of valproate for anxiety is not supported by robust clinical trials. A randomised study showed efficacy in panic disorder (Lum et al. 1991) and benefit has been reported in open studies in OCD and PTSD. The major side-effects are tremor, nausea, ataxia and weight gain and there is the potential for drug interactions via inhibition of hepatic enzymes. 

There have been three randomized clinical trials and multiple case reports and open-label trials with the tricyclic antidepressants (TCAs) in PTSD, although only one study of childhood PTSD (Southwick et al., 1994) has been reported. Robert et al. (1999) reported the use of low-dose imipramine (1 mg/kg) to treat symptoms of ASD in children with burn injuries. In this study, 25 children ages 2 to 19 years were randomized to receive either chloral hydrate or imipramine for 7 days. Ten of 12 subjects receiving imipramine experienced from half to full remission of ASD symptoms, whereas 5 of 13 subjects responded to chloral hydrate. Sleep-related flashbacks and insomnia appeared to be particularly responsive to treatment. 

To our knowledge, there have been no reports of controlled clinical trials of valproate as a prophylactic agent in bipolar disorder. Results from a number of open trials suggest that perhaps half of patients treated with valproate experience prophylactic benefit (reviewed in Keck et al. 1992a]. A placebo-controlled, double-blind study of the efficacy of the divalproex form of valproate is under way and may provide additional information regarding the use of this drug in the maintenance therapy of bipolar disorder. 

Well known for their clinical role as antimanic agents, anticonvulsants such as carbamazepine and valproate have also been used in both bipolar and unipolar TRD (Post et al. 1994a, 1994b). In one series. Post et al. (1994a) found a greater response in patients with bipolar (15/40) versus those with unipolar (2/17) TRD. Open studies of valproate also suggest limited antidepressant efficacy, but only a paucity of data with anticonvulsants on TRD exists. More recently, in open trials, lamotrigine (a partial anticonvulsant that inhibits glu-... 

Another open trial of fluoxetine was reported by Van Ameringen et al. (1993). In this study, 16 subjects with a primary diagnosis of social phobia were entered into a 12-week clinical trial. Treatment started at a dose of 20 mg/day and was increased every 4 weeks, according to clinical response and side effects, to a maximum daily dose of 60 mg. Of the 16 subjects, 10 were considered responders, 3 were nonresponders, and 3 dropped out of the trial as a result of adverse effects related to the medication. The response rate of the different subtypes of social phobia was not reported in this study. 

Clinically, haloperidol decanoate has been administered to hundreds of chronic schizophrenic patients in several open studies to determine its efficacy, pharmacokinetics, safety, and adverse effects. The trials ranged from 4 months to 2 years, with dosages ranging from 25 to 500 mg given once every 4 weeks. The results of these studies have consistently shown that depot haloperidol ... 

Lambert et al. (16) first investigated VPA in a series of clinical trials including a wide variety of patients. Twelve subsequent open-design studies, representing 297 acutely ill patients, found an overall moderate-to-marked response rate to VPA of 56%. Only one study, however, met more rigorous double-blind, placebo-controlled conditions, with a total of 17 patients on VPA (131). 

Schou et al. (159) also compared the relapse rate of patients in their double-blind clinical trial with those in their naturalistic open study and found a similar rate. 

Recently, Calabrese (240) reviewed the use of topiramate in bipolar disorder and also presented the results of two additional studies. He noted that, thus far, topiramate had been studied in 12 open clinical trials involving a total of 224 patients, mainly in manic and mixed states, and generally as an augmentation strategy. 

Risperidone Acute Clinical Trials. Hillert et al. (107) found risperidone to have both antipsychotic and antidepressive properties in 10 patients with schizoaffective disorder, depressed type. These investigators prescribed 2 to 10 mg/day for 6 weeks in an open-label pilot study, and found marked improvement in psychosis in all patients and clinically significant overall improvement in psychosis in 7 to 10 patients. Two patients required antiparkinsonian drugs otherwise risperidone was well tolerated by the group. 

Most studies in children and adolescents have been conducted with neuroleptics. A computerized literature search for the period 1974 to 1999 identified only five double-blind, placebo-controlled clinical trials that investigated the use of atypical antipsychotic medications in children and adolescents ( 166, 167). These studies involved a total of 105 patients. Numerous open-label and case series were also found. 

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