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Bioavailability of oral and intramuscular molindone hydrochloride in schizophrenic patients.

This study was designed to assess the bioequivalence of intramuscular molindone hydrochloride and marketed oral molindone. Ten schizophrenic patients (mean age, 30.2 years) received oral molindone in single daily doses of 100 or 150 mg for four to eight days followed by intramuscular molindone in single daily doses of 50 or 75 mg for four days. On the last day each molindone formulation was given, plasma samples were collected at baseline and at 0.5, 1, 2, 4, 6, 8, and 12 hours after administration. The pharmacokinetic measures of area under the curve and maximum concentration show that intramuscular molindone is 1.49 to 1.67 times more bioavailable than oral molindone. This finding indicates that once a patient's acute psychotic episode has been stabilized with intramuscular molindone, therapy can continue without interruption by substituting 1.5 mg of oral molindone for every 1 mg of intramuscular molindone. The time to maximum concentration occurred significantly earlier (P = 0.05) with intramuscular molindone (0.6 hours) than with oral molindone (1.1 hours). Elimination half-life values were approximately two hours for both formulations.

Administration, Oral

Effects of molindone on central dopaminergic neuronal activity and metabolism: similarity to other neuroleptics.

The effect of molindone on the activity of dopaminergic (DA) neurons in the rat midbrain and on DA metabolism in the striatum and olfactory tubercles was studied using extracellular single unit recording and biochemical techniques respectively. Molindone in low intravenous doses (0.4-0.8 mg/kg) was found to reverse d-amphetamine and apomorphine induced depression of DA neurons and to block apomorphine induced depression of these cells. Molindone was also found to increase dopamine synthesis and dihydroxyphenylactic acid levels in the striatum and olfacotry tubercles. In all of these respects molindone behaves identically to most classical neuroleptics. However, unlike most antipsychotic drugs previously tested, molindone failed to increase the baseline firing rate of DA cells and blocked haloperidol induced increases in DA neuron activity. In this regard molindone most closely resembles thioridazine and clozapine. Possible mechanisms of action of molindone are discussed based on these findings.

3,4-Dihydroxyphenylacetic Acid

A comparison of the abilities of chlorpromazine and molindone to interact adversely with guanethidine.

Chlorpromazine and molindone were tested for their abilities to impair conditioned avoidance behavior of rats. Chlorpromazine was effective within the dose range of 0.3 to 7.0 mg/kg (ID50approximately 2.0 mg/kg); molindone was effective within the range of 0.3 to 5.0 mg/kg (ID50 approximately 0.6 mg/kg). Behaviorally relevant doses of chlorpromazine and molindone were then tested for their effects on blood pressure and on adrenergic mechanisms. When given intravenously to anesthetized, hypertensive animals, both drugs (1.0 mg/kg) produced significant but transient vasodepression. When given intraperitoneally to anesthetized or to conscious hypertensive rats, the drugs did not produce significant effects on blood pressure. Both drugs (1.0 mg/kg) blocked responses to an alpha agonist (methoxamine), but chlorpromazine was significantly more potent than molindone. In addition, chlorpromazine produced a dose-dependent (1.0-10.0 mg/kg) inhibition of 3H-l-norepinephrine uptake into heart, but molindone at the same doses produced no inhibition of uptake. In related experiments, it was found that guanethidine (50 mg/kg) was an effective agent for lowering blood pressure of hypertensive rats. When chlorpromazine (3-10 mg/kg) was administered concomitantly with guanethidine, the blood pressure lowering properties of guanethidine were diminished or abolished. When molindone (1-10 mg/kg) was administered concomitantly with guanethidine, there was no loss of blood pressure control. It is concluded that molindone is an important drug, because it is an antipsychotic agent that does not interact adversely with guanethidine.

Animals

Molindone hydrochloride: a review of laboratory and clinical findings.

Molindone hydrochloride, a dihydroindolone neuroleptic, is structurally distinct from other classes of neuroleptics. Molindone exhibits many similarities to other neuroleptics, including dopamine receptor blockade, antipsychotic efficacy, and extrapyramidal side effects. Despite these similarities, molindone also has atypical properties and inhibits the enzyme monoamine oxidase in vitro and in vivo. Several studies have shown that molindone causes less dopamine receptor supersensitivity than other neuroleptics and thus may be less likely to cause tardive dyskinesia. It also appears to have a greater effect on mesolimbic and mesocortical dopamine neurons than on those in the nigrostriatal dopamine system. Clinically, molindone has a tendency to cause weight loss and may have less effect on seizure threshold than conventional antipsychotic agents. The authors review the laboratory and clinical data on molindone and discuss the relevance of atypical research findings to the clinical characteristics of this antipsychotic agent.

Adult

Relation of serum molindone levels to serum prolactin levels and antipsychotic response.

The antipsychotic drug molindone is considered to be atypical in its mode of action and to have mild side effects. Currently no data are available on the range of serum levels of this drug during treatment. By means of a high performance liquid chromatographic technique, serum molindone levels were measured in 14 psychotic patients receiving a wide range of doses of this drug. Molindone levels as high as 350 ng/mL were obtained and were not associated with any toxic effects. Significant relations were noted between the serum level of the drug and both serum prolactin level and treatment response. The authors suggest that molindone may have a range of serum levels consistent with therapeutic benefit. Serum molindone and prolactin levels might help assess resistance to molindone treatment.

Adult

Down-regulation of tryptamine binding sites following chronic molindone administration. A comparison with responses of dopamine and 5-hydroxytryptamine receptors.

The present study assessed changes of tryptamine, dopamine D2, 5-HT1 and 5-HT2 binding sites in rat brain following chronic treatment with low (5 mg/kg/day) and high (40 mg/kg/day) doses of molindone, a clinically effective psychotropic drug. The high-dose molindone treatment produced a decrease in the number of tryptamine binding sites while both high and low doses caused an increase in the number of dopamine D2 binding sites in the striatum. No significant changes were observed in either 5-HT1 or 5-HT2 binding sites in the cerebral cortex. Competition binding experiments showed that molindone was a potent inhibitor at dopamine D2 but less effective at tryptamine, 5-HT1 and 5-HT2 binding sites. The inhibition activity of molindone towards type A monoamine oxidase produced a significant increase in endogenous tryptamine accumulation rate which was much higher than that of dopamine and 5-HT. These findings suggest that the reduction in the number of tryptamine binding sites produced by chronic molindone administration is related to monoamine oxidase inhibition and that the increase in the number of dopamine D2 binding sites is correlated to receptor blocking activity of the drug.

Animals

Molindone: effects in pigeons responding under conditional discrimination tasks.

Pigeons were trained to respond under three conditional discrimination procedures; 1) a fixed-consecutive-number procedure with (FCN 8-SD) and without (FCN 8) an added external discriminative stimulus, 2) a delayed matching-to-sample (DMTS) procedure using 0-sec, 2-sec and 8-sec delay intervals, and 3) a repeated acquisition of behavioral chains (RA) procedure using a four-link response chain with three stimulus keys. The atypical neuroleptic agent molindone decreased accuracy under the FCN 8 at doses that had no effect on accuracy under the FCN 8-SD. Under the DMTS procedure, molindone-induced decreases in accuracy were directly related to the delay interval, with the largest relative decrements obtained at the 8-sec delay and the smallest at the 0-sec delay. Under the RA procedure, molindone decreased accuracy at doses that had little or no effect on the number of correct responses emitted. Relative to control values, molindone-induced decreases in accuracy were smallest under the DMTS and FCN 8-SD procedures and largest under the FCN 8 and RA procedures. The differential effects obtained with molindone under each of these procedures illustrate the need to employ a variety of assays when determining the behavioral actions of neuroleptics. In addition, this battery of behavioral tests may provide a useful tool for assessing the different neurochemical actions of neuroleptic compounds.

Animals

Molindone hydrochloride treatment of hospitalized children with conduct disorder.

Treatment-emergent symptoms and behavioral changes were assessed during an 8-week double-blind study comparing molindone and thioridazine in 31 aggressive hospitalized children (ages 6-11). Molindone was found to be as effective as thioridazine in this sample. Adverse effects differed (nonsignificantly) for the two groups, with more sedation in the thioridazine-treated children. Clinical records from 6 adolescent inpatients treated with molindone were reviewed as a comparison group. Molindone is a relatively safe neuroleptic for child and adolescent inpatients because of its short half-life and minimal prolonged tissue accumulation. Additional studies on different child populations are necessary before the proper indications for molindone usage in the pediatric group can be established.

Adolescent

Combined use of molindone and guanethidine in patients with schizophrenia and hypertension.

Human sympathetic nerves have a high-affinity norepinephrine uptake system. This uptake system is inhibited competitively by chlorpromazine but not by molindone, which suggests that molindone will not interact adversely with guanethidine, an antihypertensive drug that enters sympathetic nerves via the high-affinity uptake system. Accordingly, patients with concomitant schizophrenia and hypertension were treated simultaneously with molindone and guanethidine; there was no evidence of an adverse drug interaction. The data indicate that molindone and guanethidine can be used in combination safely and effectively.

Autonomic Fibers, Postganglionic

Effect of molindone on weight change in hospitalized schizophrenic patients.

A retrospective review was conducted to assess the effect of molindone on weight. Monthly weights and neuroleptic dosages during the first three months of psychiatric hospitalization were compared between matched groups of patients receiving molindone, a combination of molindone and other neuroleptics, or other neuroleptic drugs. We found no significant differences in weight gain among the three groups. Our results challenge the common opinion that molindone can be associated with a lack of weight gain compared to other antipsychotics.

Adult

Molindone and haloperidol in tardive dyskinesia.

Preliminary results are described from a study of 11 outpatients manifesting exacerbated tardive dyskinesia after tapering and withdrawal of neuroleptic medications. Patients were randomly assigned to molindone or haloperidol under double-blind placebo-controlled conditions to compare the masking effects of the two drugs. Haloperidol treatment masked withdrawal-exacerbated tardive dyskinesia more than molindone did; this difference (measured by percent change in AIMS scores) was significant (p = .04) when the dose was 200% but not 100% of the prestudy neuroleptic dose. Despite several limitations to the study, the results suggest that molindone may have less dyskinetogenic potential than haloperidol. Further research in the area of site-specificity of molindone is indicated.

Adolescent

Differences in the time course of dopaminergic supersensitivity following chronic administration of haloperidol, molindone, or sulpiride.

The onset and persistence of changes in 3H-spiroperidol binding to dopamine (DA) D2 receptors were examined in rat mesolimbic and striatal brain regions following daily administration of haloperidol, molindone, or sulpiride for 3, 7, 14, or 28 days. Neuroleptic dose equivalencies were determined by inhibition of 3H-spiroperidol in vivo binding in several rat brain regions. Changes in locomotor and stereotyped responses to the specific DA D2 agonist quinpirole were examined 3 days after the last treatment dose. Haloperidol or molindone administration increased mean stereotypy scores and striatal DA D2 receptor densities throughout the 28-day treatment period. In contrast, mesolimbic DA D2 receptor densities were transiently increased and returned to control values, after 28 days of haloperidol or molindone treatment. Sulpiride treatment increased mean stereotypy scores and striatal Bmax values, but had no effect on locomotion or mesolimbic dopamine receptor density. Additionally, the magnitude of change in the various measures of brain DA function varied among the three neuroleptic treatment groups. Results from this study suggest that mesolimbic and striatal brain regions differ in their response to long-term neuroleptic administration and that drug choice may influence the magnitude of neuroleptic-induced dopaminergic supersensitivity.

Animals

Reinstitution of neuroleptic treatment with molindone in a patient with a history of neuroleptic malignant syndrome.

The decision to reinstitute neuroleptic treatment in patients with a history of neuroleptic treatment is fraught with hazards. A case is reported in which neuroleptic treatment was successfully reintroduced with molindone after previous bouts of neuroleptic malignant syndrome (NMS) with trifluoperazine and thioridazine. Molindone may represent an alternative neuroleptic to consider in patients with a history of NMS, although all neuroleptics including clozapine and molindone may potentially precipitate this syndrome.

Adolescent

A comparison of masking effects of haloperidol versus molindone in tardive dyskinesia.

An experimental method was utilized to compare the masking effects of two neuroleptic agents--molindone and haloperidol--on 18 neuroleptic-treated schizophrenic patients exhibiting operationally defined withdrawal-exacerbated tardive dyskinesia. After a week on one of these two medications at preestablished doses equivalent to that of the pre-study neuroleptic, molindone-masked total AIMS scores by significantly less (12%) than haloperidol (27%). Similarly, during a second week when the dose of these neuroleptics was equivalent to 200% that of the pre-study dose, molindone masked the total AIMS score significantly less (23%) as compared to haloperidol (53%). Several interpretations of this finding are considered. This study demonstrates the feasibility of a method that may offer a model for understanding pharmacological differences among neuroleptic medications.

Adult

Clinical experience with molindone hydrochloride in geriatric patients.

Elderly patients (N = 28) with a variety of psychiatric disorders were treated with molindone in an 8-week open clinical trial. Many patients had concomitant medical illnesses, and many were on other medications in addition to molindone. Molindone appeared to be safe, clinically effective, and well-tolerated. The most common adverse effects were extrapyramidal side effects, but the occurrence of these symptoms was relatively low.

Age Factors

Review of clinical and laboratory experiences with molindone hydrochloride.

The literature concerning the pharmacokinetics, pharmacodynamics, receptor physiology, and clinical use of molindone is reviewed. Unanswered questions about the drug are addressed. Although molindone is reputed to have a short half-life (1.5 hours), clinical observations report a prolonged effect from a once-daily dose. Early in treatment, some patients show intolerance due to akathisia or extrapyramidal symptoms. This may be withdrawal dyskinesia due to discontinuation of another drug or an early adverse effect of molindone. Different effects on dopamine receptors have been described, but the significance of these properties for the development of tardive dyskinesia remains unclear.

Akathisia, Drug-Induced

Weight reduction in schizophrenics by molindone.

The weight-reducing property of molindone, a recently introduced antipsychotic drug, was tested in 9 hospitalized chronic schizophrenic patients. There was an average weight loss of 7.6 kg after 3 months on molindone; most of the loss occurred during the first month. The mechanism producing this weight loss is uncertain, but a central anorexigenic effect may be an important factor.

Adult

Molindone and hepatotoxicity.

An adolescent male with chronic schizophrenic disorder, paranoid type, was treated with molindone. He developed hepatotoxicity in the early treatment phase as evidenced by flu-like symptoms and laboratory abnormalities of liver functions. These symptoms and his hepatic functions improved on discontinuing molindone. Similar liver function trends were seen on reintroduction and subsequent withdrawal of the drug. Hepatic hypersensitivity has not been reported previously with the use of this drug. It is suggested that clinicians should be aware of this association and should assess hepatic functions in patients who develop a prodromal flu-like syndrome with this drug, especially in the early treatment phase.

Adolescent