Relationship between plasma desipramine levels and clinical outcome for RDC major depressive inpatients

Depressed patients (N = 31), who met Research Diagnostic Criteria for major affective disorder-depressed, were severely ill and maintained drug-free for a 1-week period on inpatient status. They received a fixed dose (150 mg/day) of desipramine for a 4-week period with drug plasma level determination and clinical ratings performed at fixed time intervals throughout the study. Despite these rigid criteria for entrance and clinical outcome measures, no obvious relationship between plasma desipramine level and clinical outcome was found. The clinical implications of this finding are discussed.

Naloxone, tardive dyskinesia, and endogenous beta-endorphin

The subjects were 13 psychiatric inpatients with tardive dyskinesia. Each subject participated in two sessions. Either naloxone (10 mg) or placebo was administered intravenously during each session. In a subset of subjects (n = 7), blood samples for beta-endorphin were drawn before and at 30 and 60 minutes after the injection. The Abnormal Involuntary Movement Scale was administered before and at 10, 20, 40, 60, 120, and 360 minutes after the injection. Double-blind procedures were maintained throughout the experiment. Neither naloxone nor placebo had any appreciable effect on the involuntary movements. Naloxone elicited a significant increase in the plasma beta-endorphin.

GLC/MS assay for loxapine in human biofluids and tissues with deuterium labeled analog as an internal standard

A quantitative gas liquid chromatographic-mass spectrometric (GLC/MS) assay was developed for the determination of loxapine in human blofluids and tissues. The assay utilizes selected ion monitoring in a GLC effluent of the molecular ion of loxapine generated by electron-impact ionization (EI). Loxapine-d3 was used as the internal standard. The assay can measure 2 ng/mL of loxapine with about 6% precision. The curve relating the amounts of loxapine added in control plasma versus the ion intensity ratio (m/e 327/330) over a large range of loxapine concentrations was linear with essentially zero intercept. The method was used for the analysis of loxapine in human urine, plasma, brain, liver, lung and spleen.

Fluphenazine blood levels and clinical response

The radioreceptor assay for neuroleptics (NRRA) holds out great theoretical promise as a method for monitoring blood neuroleptic levels, but its practical value is yet to be established. In the present study, 12 psychotic patients were followed longitudinally during treatment with oral (n = 9) and/or depot (N = 7) fluphenazine. Neuroleptic blood levels were determined both by the NRRA and by high performance liquid chromatography utilizing an electrochemical detector (HPLC). Clinical status was monitored by the Brief Psychiatric Rating Scale. Although blood levels were near the limits of sensitivity, the NRRA was able to detect the drug in most samples. HPLC was able to detect fluphenazine in less than 20% of the samples. Detectable blood levels by HPLC were associated with high blood levels by the NRRA. There was a significant correlation between blood levels as measured by the NRRA and clinical improvement. This correlation appears to be independent of the dose or route of administration of fluphenazine. Many patients were followed for several months and a few for over a year. A remarkable constancy of blood levels was found, particularly with depot administration. Given these findings, the NRRA may be an important clinical tool for monitoring patients receiving fluphenazine.

Determination of mianserin and metabolites in plasma by liquid chromatography with electrochemical detection

A procedure for the determination of mianserin, desmethylmianserin, and 8-hydroxymianserin in plasma at therapeutic concentrations by liquid chromatography with electrochemical detection is described. Following a multiple-step extraction from alkaline plasma into methyl-tert-butyl ether, the reconstituted extract was injected onto a reversed-phase trimethylsilyl-packed column and eluted with an acetate-acetonitrile mobile phase containing an ion-paired reagent. The method provides an absolute recovery of 71-76% and a day-to-day precision of 5.4-9.1% for each compound at 25 ng/ml. The minimum quantifiable level for all three compounds was 5 ng/ml (RSD greater than 11%), and the detector response was linear up to 500 ng/ml. Fixed-dose steady-state plasma level data for 34 patients are reported.

Will amitriptyline prevent the "cheese" reaction of monoamine-oxidase inhibitors?

Administration of amitriptyline greatly diminished the pressor response to intravenous tyramine in patients receiving monoamine-oxidase inhibitors (MAOIs). Dothiepin and trimipramine, however, produced little change in sensitivity to tyramine. It is suggested that a combination of amitriptyline and an MAOI, started together in a modest dose that is then increased, may protect patients against the potential dangers of eating tyramine-containing foods. However, because MAOIs allow a high proportion of ingested tyramine to be absorbed into the systemic circulation, patients treated with MAOIs, even in combination with amitriptyline, should not be encouraged to eat foods containing tyramine.

Simultaneous determination of amitriptyline, nortriptyline and their respective isomeric 10-hydroxy metabolites in plasma by liquid chromatography

An ion-pair reversed-phase liquid chromatographic method for the determination of the tricyclic antidepressant amitriptyline, the demethylated metabolite nortriptyline, and their respective cis- and trans-hydroxylated metabolites in plasma is presented. After extraction from 1 ml of plasma, the reconstituted residue was chromatographed on a trimethylsilyl packed column using a mobile phase of acetonitrile and acetate buffer with sodium heptane-sulfonate and triethylamine. Recovery of the drugs and its metabolites from plasma ranged from 56 to 99%. The method is suitable for determining plasma concentrations as low as 5 ng/ml (C.V. less than 9%) for all six compounds. Plasma concentrations of amitriptyline and its metabolites from eleven different patients are presented.

Cardiovascular effects of phenelzine and amitriptyline in depressed outpatients

Blood pressure and ECG changes were monitored in depressed outpatients treated for 6 weeks with amitriptyline, 150 mg/day, or phenelzine, 60 mg/day, as part of an ongoing double-blind study. Phenelzine produced significant decreases in blood pressure and a significant increase in orthostatic fall in pressure. Amitriptyline produced little overall change in blood pressure. The degree of MAO inhibition in phenelzine-treated patients was significantly correlated with blood pressure. Tricyclic plasma concentrations were also related to some blood pressure measures. Reported dizziness/faintness did not correlate with blood pressure changes in either group. Amitriptyline significantly increased heart rate, while phenelzine produced slowing. Amitriptyline was associated with significant prolongation of QRS and QTc but not PR intervals. Phenelzine produced significant shortening of the QTc interval.

Prenatal exposure to imipramine alters early behavioral development and beta adrenergic receptors in rats

Offspring of rats exposed to water or 15 mg/kg/dy of imipramine (IMI) on gestational day 8 through 20 were examined for behavioral and neurochemical development. IMI-treated mothers gained significantly less weight during pregnancy, but the percentage giving birth, length of gestation and litter size were unaffected. Body weights of IMI-exposed offspring were significantly lower than controls until postnatal day 14 and brain weights were lower until day 30. In IMI-exposed pups, eye-opening occurred significantly earlier, development of the surface righting reflex was delayed and development of negative geotaxis was altered. Hypothalamic levels of noradrenaline and adrenaline were unchanged in IMI pups at 7, 14 and 30 days, but dopamine levels, unaffected at 7 and 14 days, were significantly lower than controls at 30 days. The number of cortical beta adrenergic receptors, measured by [3H]dihydroalprenolol binding, was significantly decreased by 18.7% at 14 days and 9.1% at 30 days. Affinity for binding was increased at 30 days. Brain levels of IMI and its metabolite desmethylimipramine were detectable in newborns prenatally exposed to IMI and desmethylimipramine/IMI ratios were 1.8 times those found in adults. The results indicate that prenatal exposure to IMI produces behavioral and neurochemical consequences lasting well past cessation of drug exposure.

Monitoring lithium dose levels: estimation of lithium in blood and other body fluids

The theoretical basis and practical application of the analytical procedures used to quantitate lithium in biological fluids, i.e., flame emission and atomic absorption, are described in their most simple form in nontechnical language. The clinical relevance of the erythrocyte to plasma ratio, saliva, urine, and spinal fluid lithium measures is discussed. Other topics include acute treatment plasma lithium levels and maintenance treatment plasma levels, pitfalls in sample collection, availability of micro (finger prick) procedures, and laboratory accuracy and evaluation.

Simultaneous determination of imipramine, desipramine, and their 2-hydroxy metabolites in plasma by ion-pair reversed-phase high-performance liquid chromatography with amperometric detection

An ion-pair reversed-phase high-performance liquid chromatographic (HPLC) method, using an electrochemical detector, is presented for the simultaneous and rapid quantitation of imipramine desipramine, and their 2-hydroxylated metabolites in plasma. The drugs are extracted from 1 ml of plasma at pH 9.7 with ether, back-extracted into 0. M HCl, and reextracted into ether following alkalinization. An efficient electrochemical oxidation reaction at the detector electrode affords a low detection level of approximately 5 ng/ml in a mobile phase of acetonitrile--acetate buffer (40:60) containing 0.005 M heptanesulfonate. Patient data are presented as correlations between the plasma level of each hydroxy metabolite and its respective parent compound. The method is applicable to the laboratory experienced in HPLC.

Prediction of steady state plasma and saliva levels of desmethylimipramine using a single dose, single time point procedure

In normal volunteer study (20 subjects) where each ingested 75 mg desmethylimipramine (DMI), blood and saliva samples were collected at 1, 2, 3, 4, 5, 7, 12, 24, and 32 h post dose. Each subject then was given DMI 25 mg b.i.d. for 15 days. Blood and saliva samples were collected on days 3, 4, 12, 13, 14, and 15. All samples were analyzed for total DMI content. Strong correlations were found between the blood samples collected 12, 24, and 32 h post dose (r = 0.93, 0.96, 0.95) and saliva samples collected 24 and 32 h post single dose (r = 0.91, 0.84) and the subjects' respective steady states. Although the correlation between blood and saliva levels was weaker (r = 0.7) because of considerable interindividual variation in the saliva/plasma DMI ratio (16-fold variation), this ratio in individual subjects was stable. These data suggest that, as has been shown for other psychotropic drugs, single blood measures at 24 h post ingestion of 75 mg DMI can be used to predict optimal dosage in individual patients. Acceptable predictions of steady state plasma levels were obtained when this technique was applied to patient data available in the literature. It is also suggested that if the saliva/plasma ratio is established for each individual patient, their drug level monitoring may be possible using this noninvasive approach.

Clozapine: plasma levels and prolactin response

Serial plasma clozapine levels and serum prolactin levels were determined in two schizophrenic patients receiving clozapine, a novel antipsychotic drug. Despite marked therapeutic response and substantial clozapine blood levels, prolactin levels obtained 11--12 h after the last oral dose were unaffected or only minimally elevated. This confirms previous evidence of clozapine's unusual characteristics.

Determination of phenelzine in human plasma with gas chromatography-mass spectrometry using an isotope labeled internal standard

A quantitative gas chromatographic-mass spectrometric assay was developed for the determination of phenelzine in human plasma. Phenelzine, in aqueous solution or in plasma reacts at room temperature with pentafluorobenzaldehyde to form quantitatively a hydrazone derivative. The derivative has good gas chromatographic characteristics. The assay utilizes selected ion monitoring in a gas chromatographic effluent, the molecular ion generated by electron impact ionization of phenelzine derivative. Phenelzine-d, was synthesized and used as an internal standard. The assay can measure 2 ng/ml of the drug with about 10% precision. The method was used for the determination of steady state levels of phenelzine in the plasma of patients taking a therapeutic dose of the drug.

Effect of antiparkinsonian medication on plasma levels of chlorpromazine

Twenty-one chronic schizophrenics were stabilized with chlorpromazine therapy at their therapeutic dosage for one month. Trihexyphenidyl hydrochloride or identical placebo was then added according to a double-blind, split crossover design. The duration of each half of the crossover was 15 days. Steady state blood samples were drawn three times weekly during the experimental period and the amount of chlorpromazine was determined. The results indicated there were no differences in the levels obtained between the trihexyphenidyl and the placebo phases. A two-hour postdrug blood sample was also drawn at the end of each phase and again, there were no differences between the two conditions. The importance of these results is discussed.

Plasma tricyclic drug levels in amitriptyline-treated depressed patients

In a double-blind phenelzine controlled clinical trial, 49 depressed outpatients were treated with a fixed dose of amitriptyline (AMI) 150 mg/day for 6 weeks. No significant relationships were found between steady-state plasma levels of AMI and its metabolite, nortriptyline, at 4 weeks and therapeutic response at 6 weeks or side effects. In the patient subgroup with more severe endogenous symptoms, there was a general trend for a weak positive association between AMI plasma levels and clinical improvement. Plasma tricyclic determinations appear to have little if any predictive value for antidepressant effect in outpatients treated with AMI.

Effects of loxapine on the sleep of chronic schizophrenics

The sleep patterns of four male chronic schizophrenic patients were monitored throughout the various phases of a 1-year therapeutic trial with loxapine succinate, a newly developed neuroleptic. Compared with the initial drug-free baseline, the early drug period was characterized by an increase in REM percentage, REM density, and REM activity. During the drug maintenance period, the increase in REM phasic events was accompanied by an increase in total sleep. Severe insomnia was noted during the initial period of drug withdrawal. The absence of time lag between changes in drug administration schedule and the associated alterations in sleep patterns was in contrast with the time latency of the therapeutic response. This neuroleptic on sleep and on psychopathology are mediated by different mechanisms.

GLC analysis of loxapine, amoxapine, and their metabolites in serum and urine

A GLC analysis is presented for loxapine, amoxapine, and their major metabolites in serum and urine. Electron-capture detection is employed for serum analysis, and flame ionization is used for urine analysis. The procedure includes trifluoroacetylation of secondary amine functions, followed by trimethylsilylation of phenolic groups after ethyl acetate extraction of the sample. Urine requires prior enzymatic hydrolysis of conjugates. Data indicating the utility of the procedure in hospitalized patients and normal volunteers are presented.

Use of temporarily placed epicardial atrial wire electrodes for the diagnosis and treatment of cardiac arrhythmias following open-heart surgery

We retrospectively assessed our experience with the use of bipolar atrial epicardial electrodes in 70 consecutive patients following open-heart surgery. These patients, representing 1 month's experience on one of our cardiac surgical services, are a random sample of our total experience with more than 6.000 patients in whom we have routinely placed such electrodes. The atrial wire electrodes were used diagnostically and/or therapeutically in 57 patients a total of 139 times. In only 13 patients were the atrial wires not used for any reason. Atrial electrograms were recorded 63 times in 34 patients, 41 times to establish a diagnosis of an arrhythmia and 22 times to confirm the diagnosis of an arrhythmia originally suspected from interpretation of a standard or monitor electrocardiogram (ECG). Atrial pacing was used to treat abnormalities of rhythm or conduction or both in 75 instances in 49 of the 70 patients. Because of their great utility in the diagnosis and treatment of arrhythmias, we conclude that routine placement of atrial wire electrodes at the time of operation is indicated regardless of the nature of the open-heart procedure or the preoperative rhythm.

Evaluation of a slow-release lithium carbonate formulation

A slow-release lithium preparation was compared with a standard formulation in normal volunteers and in patients. Pharmacokinetic parameters of normal volunteers were examined after a single dose of each form and the steady-state levels after a b.i.d. dose of the slow-release form. These initial single-dose data suggested that the two formulations are not bioequivalent. However, the area under the curve of the two forms was similar, and the essentially complete recovery of lithium from urine in steady state indicates equal bioavailability. The patients' steady-state levels for the two formulations essentially confirmed the normal subjects' data: with the slow-release form plasma lithium levels were slightly higher, and the postdose lithium level variability was decreased by as much as 50%.

Overdrive pacing for supraventricular tachycardia: a review of theoretical implications and therapeutic techniques

Rapid atrial pacing for treatment of supraventricular arrhythmias has been demonstrated to be safe and effective. Virtually any supraventricular tachycardia with the exception of atrial fibrillation, Type II atrial flutter, and probably sinus tachycardia can be treated successfully with pacing techniques. The recognition of the advantages of cardiac pacing over drug therapy or DC cardioversion has resulted in its widespread use, especially after open-heart surgery. Although the response to overdrive pacing may not reliably identify the underlying mechanism of supraventricular tachycardia, the response of the arrhythmia to pacing (i.e., whether it is interruptable or noninterruptable), is most useful in the approach to management of the individual patient.

Clinical and plasma level characteristics of intramuscular and oral loxapine

The intramuscular and oral forms of loxapine succinate were compared in their clinical, side effect, and blood level characteristics in ten hospitalized chronic schizophrenic patients. The first phase of the study determined the single dose that produced moderate sedation (i.e., the sedation threshold), and this dose was essentially the same for the two forms. Continuous administration of the two forms using the individualized sedation threshold dosage also failed to indicate any clinical or side effect differences in the two forms. The blood level characteristics, however, did differ between the two forms. The kinetic studies indicated that there was a larger are under the loxapine curve with the intramuscular form than with the oral form, while the 8-OH loxapine area was larger with the oral form. The steady-state studies also showed that the i.m. form had higher loxapine levels than the oral form. The significance of these findings, both clinically and in terms of the relative activity of loxapine and its metabolites, is discussed.

Prediction of individual dosage of nortriptyline

The authors describe a technique that enables a physician to determine individual patient dosage requirements for nortriptyline from a single 24-hour blood sample. Because the technique reveals immediately those patients at the extremes of dosage ranges, toxicity and the need for time-consuming titration of the dosage regimen can be avoided.

Plasma level monitoring of antipsychotic drugs

Psychotic patients treated with identical doses of antipsychotic drugs have been shown to have great interindividual differences in their steady state plasma concentration. Therefore, monitoring treatment by dosage adjustment alone is of little value. If antipsychotic blood levels can be related to clinical response then their routine measurement may well result in well defined guidelines to individualised optimal dosage. Despite the considerable effort expended in this field and the many interesting testable hypotheses generated, little substantive evidence for an acceptable plasma level monitoring guide has been reported to date. Work on metabolite level profiles, intra- and extracellular drug concentration differences, more detailed clinical rating scales, and improved experimental design, all show great promise for the future. Investigation of the pharmacokinetics and the elucidation of the often complex metabolic pathways of individual antipsychotic drugs are generating the data base required for the rational pharmacotherapy of these most severely ill patients. Until more data are available, routine monitoring of antipsychotic drug plasma levels remains of research interest.

Relationship between age and tricyclic antidepressant plasma levels

Older depressed patients treated with imipramine or amitriptyline developed higher steady-state plasma levels of imipramine, desipramine, and amitriptyline. In imipramine-treated patients this finding was associated with a decreased rate of drug elimination from plasma. These findings provide at least a partial explanation for the increased susceptibility of the older patient to tricyclic antidepressant side effects and also provide a pharmacological rationale for use of lower dosages in this age group.

The 24-hour lithium level as a prognosticator of dosage requirements: a 2-year follow-up study

The authors have previously described a technique whereby individual lithium dosage requirements can be predicted from 24-hour blood samples. Further experience over a 2-year period has shown the predictions to be reproducible over time. A micromethod for lithium determination is described, as are several cases in which aberrant results were found to indicate inadequate laboratory techniques or patients' failure to take medication. Because the technique reveals immediately those patients at the extremes of dosage ranges, toxicity and the need for frequent sampling can be avoided.

Butaperazine pharmacokinetics. Effect of dosage regimen on steady state blood levels

Experimental evidence showed that a higher whole blood steady state drug plasma level was achieved when a patient was given medication three times a day compared to the same total daily dose once a day. In addition, evidence indicated possible enzyme induction by butaperazine in one patient. We have demonstrated that the general stochastic theory developed to investigate the pharmacokinetics of lithium carbonate "in vivo" has more general applicability in that it applies also to butaperazine, and facilitates interpretation of findings (without blood level data) in one other drug study.

The iodine requirement and influence of iodine intake on iodine metabolism and thyroid function in the adult beagle

Various aspects of iodine metabolism were studied in adult beagles maintained at iodine intake levels ranging from 480 to 20 mug/day. On the basis of changes in radioiodine metabolism, the minimum daily iodine requirement of the adult beagle was found to be 140 mug. Although striking changes were observed in radioiodine metabolism when iodine intake was reduced to 90mug/day, serum T4 and T3 levels were unaffected. Marked reductions in serum T4 occurred in dogs restricted to an iodine intake of 50 or 20 mug/day, but even at these low levels of iodine intake there were only slight reductions in serum T3 concentration and a eumetabolic state was maintained. Prolonged iodine deficiency (8-12 months) resulted in variable patterns of thyroid histology, which were related to differences in thyroidal 127I content and in the rate of release of radioiodine from the thyroid. The heterogeneity in thyroid morphology and iodine kinetics did not, however, have a significant effect on serum T4 and T3 levels.

Lithium kinetics in man: effect of variation in dosage pattern

1. Utilizing a general stochastic theory of drug kinetics we have demonstrated that from the serum concentration curve derived from a single dose of lithium, it is possible to predict the steady state concentration, the time required to reach steady state, the dependency of these quantities on the time interval between drug administrations and the fluctuations in plasma level under steady state conditions.2. It has been shown in general that the more frequently the drug is administered the higher is the steady state level, the shorter is the time required to reach steady state, and the smaller are the fluctuations.