Biomedical subjects

P J Perry

Publications and source records attributed to P J Perry.

At least 19 recordsLinked to original sources

PubMed1998

Olanzapine: a serotonin-dopamine-receptor antagonist for antipsychotic therapy.

The pharmacology, pharmacokinetics, clinical efficacy, adverse effects, drug interactions, dosage and administration, and cost of olanzapine are reviewed. Olanzapine is a serotonin-dopamine-receptor antagonist indicated for use in the treatment of schizophrenia and other psychotic disorders. The affinity of olanzapine for neuroreceptors is similar to that of clozapine. The drug is well absorbed from the GI tract; food has no effect. Olanzapine is more effective than placebo and equal to haloperidol in reducing psychotic symptoms on two rating scales. However, unlike typical dopamine-receptor antagonists used for antipsychotic therapy, olanzapine is more effective in reducing the negative symptoms of schizophrenia. The most frequent adverse drug reactions (ADRs) associated with olanzapine are somnolence, agitation, insomnia, and headache. Constipation and dry mouth occur as dose-dependent ADRs. Unlike clozapine, olanzapine does not cause agranulocytosis. No cases of tardive dyskinesia or neuroleptic malignant syndrome have been reported. Olanzapine has been associated with slight increases in hepatic transaminases. More study is needed to determine whether olanzapine interacts significantly with other drugs. The recommended starting dosage is 5-10 mg orally once daily. Efficacy beyond six weeks has not been evaluated; patients treated for longer than six weeks should be periodically reassessed. Olanzapine costs about 10 times more than typical antipsychotics because a generic version is not available; however, olanzapine costs less than clozapine therapy and may cost less than haloperidol in terms of total health care costs. Olanzapine offers an effective alternative for treating schizophrenia and has a favorable adverse-effect profile.

Antipsychotic Agents↗

PubMed1998

Haloperidol plasma levels and dose optimization.

OBJECTIVE: This study was designed to test the practical utility of haloperidol plasma level determinations in the management of schizophrenic patients who show poor initial responses to haloperidol. METHOD: Inpatients with acute exacerbations of DSM-III schizophrenia (N = 66) were randomly assigned to receive fixed haloperidol doses intended to achieve plasma levels of 8-18 ng/ml or of 25-35 ng/ml. Patients whose scores on the Brief Psychiatric Rating Scale (BPRS) failed to improve by at least 30% at the end of 3 weeks were then subject to dose reassignment. RESULTS: Among the patients who completed the first phase of the protocol, 30 had steady-state haloperidol plasma levels of less than 18 ng/ml, and 22 had levels that exceeded 25 ng/ml; 14 had intermediate plasma levels of 18-25 ng/ml. A survival analysis of time to 30% improvement significantly favored the two lower plasma level groups, although side effect ratings did not differ. Of the 30 patients whose BPRS scores failed to improve by 30% after 3 weeks, 11 and five were randomly assigned to receive lower and higher doses, respectively. Those whose dose was lowered experienced significantly more improvement in the subsequent weeks than did those whose dose was increased. CONCLUSIONS: Haloperidol plasma levels that substantially exceed 18 ng/ml may be countertherapeutic. In particular, increases in dose beyond this level are not efficacious for patients who have not responded to lower doses.

Adolescent↗

PubMed1997

Dexfenfluramine hydrochloride: an anorexigenic agent.

The pharmacology, pharmacokinetics, efficacy, and adverse effects of dexfenfluramine hydrochloride are reviewed. Dexfenfluramine, the dextrorotatory isomer of fenfluramine, is indicated for use in the management of obesity in patients with a body mass index of > or = 30 kg/m2, or > or = 27 kg/m2 in the presence of other risk factors. Unlike fenfluramine, dexfenfluramine is a pure serotonin agonist. Dexfenfluramine may mimic the effect of carbohydrate intake. Systemic bioavailability is about 68%, and the drug is metabolized in the liver. In randomized, placebo-controlled trials, dexfenfluramine was effective in reducing weight in obese patients given the drug for three or six months. In trials lasting one year, the statistically significant weight loss occurred during months 4 to 6. Dexfenfluramine reduces blood pressure, percent glycosylated hemoglobin, and concentrations of blood glucose and blood lipids, but these benefits may be indirect. Dexfenfluramine may also be of some value in controlling eating habits in diabetic patients, preventing weight gain after smoking cessation, and treating bulimia, seasonal affective disorder, neuroleptic-induced obesity, and premenstrual syndrome. Dexfenfluramine's most frequent adverse effects are insomnia, diarrhea, and headache; it has also been associated with primary pulmonary hypertension. The drug should not be combined with other serotonergic agonists because of the risk of serotonin syndrome. The recommended dosage is 15 mg twice daily. Dexfenfluramine is effective in the treatment of obesity in selected patients. Because its efficacy is lost after six months of continuous treatment, it should be viewed primarily as an adjunct to diet and exercise.

Animals↗

PubMed1997

Olanzapine plasma concentrations and clinical response in acutely ill schizophrenic patients.

Olanzapine is an atypical antipsychotic effective in the treatment of schizophrenic patients. After a 2- to 9-day placebo lead-in, 79 inpatients with schizophrenia according to DSM-III-R criteria were placed on an olanzapine dosage of 10 mg/day or 1 mg/day for up to 6 weeks. Blood samples were obtained weekly during this period. Receiver operating characteristic curve analyses of Brief Psychiatric Rating Scale (BPRS) and Positive and Negative Syndrome Scale rating scale data suggested a minimum effective therapeutic concentration of 9 ng/mL. Using an intent-to treat analysis, 45% of the patients with olanzapine plasma concentrations > or = 9.3 ng/mL responded (> or = 20% decrease in BPRS), whereas only 13% of the patients with concentrations < 9.3 ng/mL responded. Use of olanzapine plasma concentrations of > 9 ng/mL as a predictor for treatment response in acutely ill schizophrenic patients is practicable because this therapeutic marker significantly increases the likelihood of a patient responding to olanzapine.

Adult↗

PubMed1997

The effects of anabolic steroids on driving performance as assessed by the Iowa Driver Simulator.

The effect of physiologic (100 mg/wk) and supraphysiologic (250 and 500 mg/wk) doses of testosterone cypionate (TC) on automobile driving were studied using the Iowa Driver Simulator. Six normal subject volunteers were studied off TC and on TC once steady-state concentrations were achieved after at least three weeks of dosing. Despite the administration of supraphysiologic testosterone doses, an increase in aggressive driving behavior was not detected. Likewise, corresponding psychometric testing using the Buss-Durkee Hostility Inventory to assess aggression was unable to detect any change in aggression in the test subjects. Although aggressive driving behavior may be increased by testosterone administration, the drug itself may not be responsible for these effects. Supraphysiologic doses greater than 500 mg/wk and a semi-controlled research environment may be necessary to produce this effect since case reports of AAS abuse causing altered driving behavior may be multifactorial in nature.

Adult↗

PubMed1997

Detection of anabolic steroid administration: ratio of urinary testosterone to epitestosterone vs the ratio of urinary testosterone to luteinizing hormone.

Our goal in this study was to determine whether the urinary ratio of testosterone to luteinizing hormone (T/LH) as an indicator of exogenous anabolic steroid (AS) use is superior to the urinary ratio of testosterone to epitestosterone (T/E). After 2 weekly placebo injections, 19 subjects were given testosterone cypionate (TC) injections of 250 or 500 mg/week for 14 weeks followed by 14 weekly placebo injections. Patients were considered to have ceased taking TC if they tested negative 9 weeks after their last injection. For detection of illicit or supraphysiological TC (AS) use, the urinary T/E ratio of > or = 6 yielded a false-negative rate of 46% and a false-positive rate of 4%. However, a urinary T/LH ratio of > or = 30 produced a false-negative rate of only 24% and a false-positive rate of 13%. We conclude that the urinary T/LH ratio of > or = 30 is a more sensitive marker of AS use than the urinary T/E ratio of > or = 6 and remains sensitive for twice as long as urinary T/E.

Adolescent↗

PubMed1997

Testosterone suppression of the HPT axis.

BACKGROUND: Although studies have demonstrated the suppression of normal gonadal function in the experimental setting, the specific mechanisms by which androgenic-anabolic steroids impact male gonadal function remain ill defined. Following 2 consecutive weekly injections of an identically appearing testosterone cypionate (TC) placebo, subjects were randomized to a TC dose of 100 mg/wk, 250 mg/wk, or 500 mg/wk. Following the last weekly injection of active agent the subjects received 12 consecutive weeks of TC placebo injections. RESULTS: Spermatogenesis was impaired by each of the doses of TC employed in this study, but the observed decreases in, sperm count were neither strictly dose dependent nor consistent between individuals treated with the same dose. Basal leuteinizing hormone (LH) and follicle stimulating hormone (FSH) became undetectable 2 weeks after the start of 250 and 500 mg/wk TC injections and were lost within 5 to 6 weeks of starting 100 mg doses. Pituitary gonadotropin responses to leutinizing hormone releasing hormone (LHRH) disappeared more slowly with FSH responses being lost 1 to 3 weeks after the loss of basal FSH activity. Leuteinizing hormone responses to LHRH appeared to be suppressed last, disappearing 4 to 6 weeks after FSH responses to LHRH. CONCLUSIONS: Exogenous testosterone-mediated inhibitory influences on the hypothalamic-pituitary-testicular axis were reversed following the cessation of drug treatment.

Adolescent↗

PubMed1996

Effect of grapefruit juice on cyclosporine pharmacokinetics in renal transplant patients.

This study investigated the effect of grapefruit juice on cyclosporine A (CsA) bioavailability in 10 renal transplant patients. Under CsA steady state conditions, patients were randomly administered their usual dose of CsA with either 8 ounces of grapefruit juice or 8 ounces of water. Using a crossover design, a 12-hr pharmacokinetic study was then conducted. Grapefruit juice increased the area under the concentration versus time curve (4218+/-1497 ng x hr/ml [grapefruit juice] vs. 3415+/-1288 ng x hr/ml [water], P=0.029) and 12-hr trough (244+/-214 ng x ml [grapefruit juice] vs. 132+/-56 ng x ml [water], P=0.09), but it did not change peak concentration (734+/-290 ng x ml [grapefruit juice] vs. 708+/-305 ng x ml [water], P=0.76). In addition, grapefruit juice delayed the time to peak concentration compared with water (5.4+/-3.0 hr [grapefruit juice] vs. 2.8+/-0.8 hr [water], P=0.025). These data suggest that concurrent administration of grapefruit juice with CsA will delay the absorption of CsA and increase the drug exposure of CsA without changing peak concentration.

Adult↗

PubMed1996

Pharmacotherapy for major depression with melancholic features: relative efficacy of tricyclic versus selective serotonin reuptake inhibitor antidepressants.

The effectiveness of tricyclic antidepressants (TCAs) and selective serotonin reuptake inhibitors (SSRIs) were contrasted in endogenous/melancholic depression. By reviewing Hamilton Depression Rating data from controlled trials, the data indicate that TCAs are consistently more effective than the SSRIs. Despite the wide use of SSRIs in the treatment of depression, it seems reasonable that clinicians subtype their depressed patients and treat melancholic patients first with a course of TCAs. For melancholic patients who have not responded to a SSRI, pharmacotherapeutic alternatives include (1) a TCA alone; (2) TCA augmentation of the SSRI, or (3) lithium augmentation of the SSRI.

Antidepressive Agents, Tricyclic↗

PubMed1996

The effect of exogenous testosterone on total and free prostate specific antigen levels in healthy young men.

PURPOSE: We evaluated the effect of exogenous testosterone administration on serum total and free prostate specific antigen (PSA) in healthy young men. MATERIALS AND METHODS: Nine volunteers received either 100, 250 or 500 mg. testosterone by intramuscular injection each week for 15 weeks. Blood was drawn every other week for 28 weeks and at week 40. Serum total and free PSA, and total and free testosterone were measured and compared to baseline values. RESULTS: Significant elevations in total and free testosterone occurred but no significant change in serum total and free PSA was detected. CONCLUSIONS: Serum PSA is not responsive to elevated serum testosterone levels in healthy young men. PSA metabolism in the normal prostate is unclear but our findings may have implications for differentiation of pathological conditions of the human prostate.

Adult↗

PubMed1996

Steroids.

Explore the source record for details and available documents.

Anabolic Agents↗

PubMed1995

Nefazodone: a new antidepressant.

The chemistry, pharmacology, pharmacokinetics, and clinical efficacy of nefazodone hydrochloride, a new antidepressant, are described. Nefazodone enhances serotonin (5-hydroxytryptamine [5-HT]) synaptic transmission by acting as an antagonist at 5-HT2 receptors and by inhibiting the reuptake of 5-HT. These two mechanisms combined may enhance 5-HT1A-mediated transmission. In addition, nefazodone weakly inhibits the reuptake of norepinephrine. Nefazodone is a structural analogue of trazodone but is pharmacologically distinct. In placebo-controlled trials, nefazodone was as effective as imipramine for the treatment of major depression and produced clinical benefits in patients with depression-related anxiety and sleep disturbances. More than 2000 patients have received nefazodone in clinical trials. The most commonly reported adverse drug reactions (ADRs) are asthenia, somnolence, dry mouth, nausea, constipation, dizziness, lightheadedness, confusion, abnormal vision, and blurred vision. The incidence of sexual-dysfunction ADRs may be less than that reported for other antidepressants. Nefazodone does not inhibit rapid-eye movement sleep. Nefazodone, an inhibitor of the hepatic P-450 isoenzyme CYP3A4, may increase concentrations of drugs metabolized by this isoenzyme, such as terfenadine, astemizole, triazolam, alprazolam, and midazolam. Caution should be exercised in administering nefazodone hydrochloride with triazolobenzodiazepines, and coadministration with terfenadine or astemizole is contra-indicated. The dosage should start at 100 mg twice daily and then be increased, depending on occurrence of ADRs and the patient's clinical response, to 300-600 mg daily. In elderly or debilitated patients, the initial dosage should be half the usual dosage. Nefazodone hydrochloride is as effective as other available antidepressants and may cause fewer ADRs.

Animals↗

PubMed1995

Clinical use of the newer antipsychotic drugs.

The clinical use of clozapine and risperidone is reviewed. Traditional antipsychotic drugs are effective for treating the positive symptoms of schizophrenia but have little or no effect on the negative symptoms of this disease. Newer antipsychotic agents, such as clozapine and risperidone, are effective for treating both positive and negative symptoms in acutely ill and treatment-resistant patients. Clozapine and risperidone also have a lower incidence of extrapyramidal symptoms (EPS) than traditional antipsychotic drugs. Three hypotheses have been proposed to account for the newer agents' ability to relieve negative symptoms: (1) Improvement in negative symptoms may be linked to improvement in positive symptoms. (2) Negative symptoms may improve in the absence of the EPS often caused by traditional agents. (3) The newer antipsychotic agents may directly affect the neural circuits that trigger negative symptoms.

Adult↗

PubMed1995

Bupropion versus methylphenidate in the treatment of attention-deficit hyperactivity disorder.

OBJECTIVE: In the treatment of attention-deficit hyperactivity disorder (ADHD), the efficacy of the tricyclic antidepressants and monoamine oxidase inhibitor antidepressants has been compared with that of both placebo and the stimulants (methylphenidate and/or dextroamphetamine). However, the effectiveness of bupropion has been contrasted only with placebo. The primary aim of this study was to contrast the efficacy of bupropion with that of methylphenidate in the treatment of ADHD. METHOD: A double-blind, crossover design was used in this study. After a 14-day medication washout period, 15 ADHD subjects (7 to 17 years old) were randomized to either methylphenidate or bupropion for 6 weeks, washed out for an additional 2 weeks, and then "crossed over" to the other drug. Methylphenidate was titrated to the maximum effective dose of 0.4 to 1.3 mg/kg per day (mean 0.7 mg/kg per day) and bupropion was titrated to an effective dose ranging from 1.4 to 5.7 mg/kg per day (mean 3.3 mg/kg per day). RESULTS: Both methylphenidate and bupropion produced significantly greater (p < .001) and equivalent improvement on the Iowa-Conners Teacher's Rating Scale according to both the subjects' parents and teachers. The same pattern of improvement was also noted for improvement on the Clinical Global Impression Scale, Kagan's Matching Familiar Figures Test, Continuous Performance Test, Children's Depression Inventory, Children's Manifest Anxiety Scale, and Rey Auditory-Verbal Learning Test. CONCLUSIONS: In this double-blind, crossover trial, bupropion and methylphenidate were both effective and did not differ in their overall efficacy as treatments for ADHD.

Adolescent↗

PubMed1994

Venlafaxine: a heterocyclic antidepressant.

The pharmacology, pharmacokinetics, and clinical efficacy of venlafaxine hydrochloride, a new antidepressant, are described. Venlafaxine inhibits the reuptake of serotonin, norepinephrine, and, to a lesser extent, dopamine. In animal models, it does not significantly inhibit muscarinic, histaminic, or adrenergic receptor activity and does not inhibit monoamine oxidase. Venlafaxine is rapidly absorbed and metabolized in the liver to its active metabolite, O-desmethylvenlafaxine (ODV). Time to peak concentration is one to two hours for the parent compound and four to five hours for ODV. The pharmacokinetics of venlafaxine might be dose-dependent, although pharmacokinetic studies have had conflicting results. The major route of elimination is renal; thus, patients with renal dysfunction may require lower doses. In double-blind, placebo-controlled trials of venlafaxine for maintenance therapy, venlafaxine has shown effective antidepressant activity in severely ill patients with major depression. Antidepressant effectiveness may be apparent within two weeks; this finding needs to be replicated. The dosage is 75-375 mg/day administered in two or three divided doses. The strength of the antidepressant response may be correlated with increasing dosage. Nausea is the most commonly reported adverse drug reaction (ADR). Others include somnolence, dizziness, dry mouth, and sweating. All ADRs have commonly occurred at the beginning of therapy and decreased with time. Overall, venlafaxine is well tolerated. Venlafaxine is as effective as other available antidepressants. It may cause fewer anticholinergic, antihistaminic, and antiadrenergic ADRs and may have a quicker onset of therapeutic action than existing antidepressants.

Antidepressive Agents, Second-Generation↗

PubMed1994

Structure-activity studies on 2-aryl-4H-3,1-benzoxazin-4-ones.

Eight benzoxazin-4-ones related in structure to NSC 341964 (1) have been tested for cytotoxicity in two different cell systems. Two of the benzoxazin-4-ones (3 and 10) showed good cytotoxicity (ID50 = 9.9 and 8.9 microM) in P388 cells. The nitrobenzoxazin-4-one (10) caused a significant alteration in cell cycle distribution when administered to P388 cells and was an inhibitor of porcine pancreatic elastase. Structure-activity relationships are discussed.

Animals↗

PubMed1994

Sertraline-phenelzine drug interaction: a serotonin syndrome reaction.

OBJECTIVE: To report a serious drug interaction possibly occurring with the monoamine oxidase inhibitor phenelzine and the selective serotonin reuptake inhibitor sertraline. CASE SUMMARY: A 61-year-old woman with treatment-refractory major depressive disorder was being treated unsuccessfully with lithium, phenelzine, thioridazine, and doxepin. Sertaline 100 mg/d was added to the patient's therapy. Within three hours of ingesting the first dose, the patient experienced a dramatic increase in her temperature, pulse, and respirations along with labile blood pressure, and symptoms of rigidity, diaphoresis, shivering, and decreased sensorium. The patient was transported to the emergency room and treated with diazepam 10 mg iv, followed by midazolam 10 mg iv for control of rigidity. She was also intubated. The patient then experienced precipitous falls in her blood pressure and respiratory rate. Ice packs combined with a cooling blanket and dantrolene 80 mg iv were administered to control fever and rigidity, respectively. She had an initial working diagnosis of neuroleptic malignant syndrome, which was later changed to serotonin syndrome. Dantrolene was continued for 72 hours at which time the patient was extubated and transferred to a psychiatric unit. CONCLUSIONS: Selective serotonin reuptake inhibitor antidepressants should not be combined with monoamine oxidase inhibitor antidepressants because of the risk of serotonin syndrome.

1-Naphthylamine↗

PubMed1994

Plasma clozapine concentrations as a predictor of clinical response: a follow-up study.

We investigated the relationship between plasma clozapine concentrations and clinical response in treatment-refractory schizophrenic patients. In a previous study, we found that plasma drug concentrations above 350 ng/mL maximized clinical response in a group of 29 patients. This study represents a follow-up of these original 29 patients over approximately 2 1/2 years of clozapine treatment. We found that during the initial 6-week trial of clozapine, 38% (N = 11) of the patients were considered to be responders. With continued treatment, we found that 58% (14 of 24) were classified as responders. Consistent with our previous study, we observed that plasma concentrations were helpful in predicting response. Five of 7 patients who had unsatisfactory response became responders when their plasma clozapine concentrations increased to above 350 ng/mL. We conclude that the assessment of plasma clozapine concentrations as a guide to dose adjustment may be useful in maximizing response.

Adult↗