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Amitriptyline plasma levels and therapeutic response.

Eighteen depressed outpatients were treated for 6 wk with amitriptyline. Clinical improvement was monitored using the Hamilton Depression Rating Scale administered by two psychiatrists blind to the tricyclic used for treatment, dosage, and plasma levels. Amitriptyline and its desmethyl metabolite, notriptyline, were assayed twice weekly by gas chromatography-mass fragmentography. For the 17 patients having total tricyclic plasma levels between 0 and 250 ng/ml, there was a negative correlation between the Hamilton score and the mean total tricyclic level (p less than 0.01) and amitriptyline level (p less than 0.005). The mean nortriptyline level did not significantly correlate with the Hamilton score. The 10 patients having mean total tricyclic levels above 95 ng/ml had lower median Hamilton scores at week 3 (p less than 0.025) and at week 6 (p less than 0.0025) than those whose tricyclics were lower. The percentage of recovered patients increases significantly as the plasma levels rise to 250 ng/ml, the maximum plasma level considered in this study.

Adolescent↗

Amitriptyline plasma levels and clinical response in primary depression.

Sixteen patients with primary depression were treated for 4 wk with amitriptyline. After clinical diagnoses were determined, patients entered a double-blind protocol (amitriptyline or placebo) and their clinical status was determined with the Hamilton Depression Rating Scale by raters blind to the drug type, its dosage and plasma levels. Amitriptyline (AT) and nortriptyline (NT) plasma levels were assayed twice weekly by gas chromatography-mass spectrometry. In the 16 patients, a negative correlation between the Hamilton Score and the mean total tricyclic level (p less than 0.01), as well as with individual plasma levels, was found at the end of the treatment period. When the group was divided into clinical responders and nonresponders, the mean total tricyclic (AT + NT) levels discriminated the two groups by day 12 (p less than 0.001) as well as at the end of the protocol (day 26, 88% of the patients were classified correctly if an arbitrary level of 200 ng/ml total tricyclic plasma level was chosen). These results strongly suggest the presence of a positive correlation between plasma levels and clinical improvement in patients with primary depression.

Adult↗

Plasma levels of a new pelletized form of amitriptyline for maintenance therapy.

Plasma levels of amitriptyline and nortriptyline were measured in volunteers after one week of daily dosage with either 25 mg t.i.d. of standard amitriptyline tablets or a single 75-mg capsule of a new pelletized form of amitriptyline. Concentrations of both compounds were essentially equal at the end of one week's dosage with either dosage form but were somewhat higher throughout the dosing time interval for the pelletized drug.

Adult↗

Contribution to the pharmacokinetics of amitriptyline.

The clinical pharmacokinetics of amitriptyline were studied in four volunteers after the oral administration of 75 mg. Peak amitriptyline plasma concentrations ranged from 10.8 to 43.7 ng/ml. The disappearance was biphasic and followed first-order kinetics. The mean elimination half-life was 36.1 hours. The mean estimated first-pass metabolism of amitriptyline was 60 per cent. Significant quantities of the metabolite, nortriptyline, were produced although peak concentrations ranged from only 5.9 to 12.3 ng/ml. The relationship between these findings to clinical practice and earlier reports is discussed.

Adult↗

Biowaiver monographs for immediate release solid oral dosage forms: amitriptyline hydrochloride.

Literature data relevant to the decision to allow a waiver of in vivo bioequivalence (BE) testing for the approval of immediate release (IR) solid oral dosage forms containing amitriptyline hydrochloride are reviewed. Its therapeutic uses, its pharmacokinetic properties, the possibility of excipient interactions and reported BE/bioavailability (BA) problems are also taken into consideration. Literature data indicates that amitriptyline hydrochloride is a highly permeable active pharmaceutical ingredient (API). Data on the solubility according to the current Biopharmaceutics Classification System (BCS) were not fully available and consequently amitriptyline hydrochloride could not be definitively assigned to either BCS Class I or BCS Class II. But all evidence taken together, a biowaiver can currently be recommended provided that IR tablets are formulated with excipients used in existing approved products and that the dissolution meets the criteria defined in the Guidances.

Administration, Oral↗

High-performance liquid chromatographic determination of perphenazine and amitriptyline hydrochloride in two-component tablet formulations.

A rapid, precise, and accurate high-performance liquid chromatographic procedure is presented for the simultaneous determination of perphenazine and amitriptyline hydrochloride in two-component tablet formulations. An aliquot of a methanolic extract of the tablet, containing trifluoperazine hydrochloride as an internal standard, is chromatographed on a nitrile bonded phase microparticulate column using a 0.005 M ammonium acetate-methanol (20:80) mobile phase. Quantitation is by peak area. The relative standard deviations for the procedure are 0.34 and 0.54% for the simultaneous determination of perphenazine and amitriptyline, respectively. Eight commercial tablet formulations were analyzed and found to contain 96.5-101.5 and 96.5-103.3% of the labeled amounts of perphenazine and amitriptyline hydrochloride, respectively.

Amitriptyline↗

Effect of amitriptyline on polarography of chlordiazepoxide.

With increasing amounts of electroinactive amitriptyline, each of the three chlordiazepoxide reduction waves shifted to more cathodic half-wave potentials and decreased in limiting current. The shift was most pronounced up the 1:1 mole ratio but continued up to ratios of 200:1. This behavior was observed in several supporting electrolytes and was not due to change in pH since this factor was maintained constant as the amitriptyline concentration was increased. Shifts in E1/2 and reductions in limiting current may arise in several ways, such as complex formation between the two drugs or adsorption of the amitriptyline onto the surface of the dropping mercury electrode hindering chlordiazepoxide reduction. Most data point to adsorption as the cause.

Amitriptyline↗

Stability of amitriptyline hydrochloride in a commercial aqueous solution.

A commercial amitriptyline hydrochloride solution was stored at 80 degrees for up to 3 months. High-performance liquid chromatography showed no evidence of amitriptyline hydrochloride degradation. The method also indicated that two reported degradates, 3-(propa-1,3-dienyl)-1,2;4,5-dibenzocyclohepta-1,4-diene and dibenzosuberone, were present at levels less than 0.1% (the detection limit of the method) under the storage conditions. The stability of the commercial solutions is attributed to their relatively low ratio of headspace oxygen to amitriptyline hydrochloride.

Amitriptyline↗

Simultaneous high-performance liquid chromatographic determination of chlordiazepoxide and amitriptyline hydrochloride in two-component tablet formulations.

A rapid, precise, and accurate high-performance liquid chromatographic procedure is presented for the stimultaneous determination of amitriptyline hydrochloride and chlordiazepoxide in two-component tablet formulations. The impurities and decomposition products of both components were separated, making the determination specific for amitriptyline hydrochloride and chlordiazepoxide. The method was used for the assay, content uniformity, and dissolution testing of dosage forms containing 5--30 mg of chlordiazepoxide and 12.5--75 mg of amitriptyline.

Amitriptyline↗

Frequency-dependent effects of amitriptyline and maprotiline on conduction in the guinea pig His-Purkinje-system in vivo.

In the Cardiac Arrhythmia Suppression Trial antiarrhythmic drug therapy with slow kinetic sodium channel blockers (class Ic antiarrhythmic drugs) was associated with excess mortality, presumably due to drug induced proarrhythmia. It has been suggested that the degree of rate-dependent conduction slowing produced by agents that have sodium channel blocking properties may be related to the proarrhythmic propensity of these agents. In the present study, rate-dependent conduction slowing by the antidepressants amitriptyline and maprotiline was investigated in anesthetized guinea pigs. After electrical ablation of the sinus node the left atrium was stimulated at cycle lengths between 200 ms and 500 ms. His bundle electrograms were registered by means of an epicardial electrode. Drugs were administered by i.v. infusion of 0.2 mg kg-1 min-1 for 30 min followed by 0.1 mg kg-1 min-1 for up to 30 min. Both drugs produced substantial rate-dependent conduction slowing within the His-Purkinje-system. The relationship between pacing rate and conduction slowing was well fitted by linear regression. The steepness of the regression line was significantly greater for amitriptyline than for maprotiline (slope factors: 9.10 x 10(-4) +/- 7.85 x 10(-5), n = 6, vs. 6.29 x 10(-4) +/- 2.97 x 10(-5), n = 6, P < 0.001), indicating that conduction slowing by amitriptyline exhibits a greater degree of rate-dependence than conduction slowing by maprotiline.(ABSTRACT TRUNCATED AT 250 WORDS)

Amitriptyline↗

The drug treatment of depression in general practice: a comparison of nocte administration of trazodone with mianserin, dothiepin and amitriptyline.

This 6-week, double-blind, randomised, multicentre study was performed to assess the efficacy and tolerability of evening administration of 150 mg trazodone as an initial and maintenance therapy and to compare this regimen with recommended dosages of mianserin, dothiepin and amitriptyline in the treatment of depressed, adult, general practice patients. A total of 227 eligible depressed patients were recruited into the study by a panel of general practitioners. One hundred and twelve patients were randomised to receive trazodone therapy, 36 received mianserin, 35 received dothiepin and 44 received amitriptyline. Trazodone was administered as a single daily dose of 150 mg. Mianserin was given at a dose of 30 mg for the first 7 days followed by 60 mg daily for the remaining 5 weeks. Dothiepin and amitriptyline were both given at a dosage of 75 mg daily for the 1st week; this was then increased to 150 mg and 100 mg, respectively, for the final 5 weeks of the study. Efficacy of the four treatments was assessed using the modified Hamilton depression rating scale scores and by the Investigator's judgment of both the global severity and improvement of the condition. No significant differences were shown, using any measure of efficacy, between trazodone and any of the three comparator drugs. All treatments resulted in significant improvement in both Ham-D scores and global measures over the period of the study. Using a total side-effect score to assess the incidence and severity of adverse events and adjusting for baseline differences, the four treatments were found to differ.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

The effect of a lipid suspension on amitriptyline disposition.

A 5-h infusion of a lipid suspension or saline was given on separate occasions to four healthy volunteers taking amitriptyline. Mean plasma levels of amitriptyline plus nortriptyline were 14% higher at the end of the lipid infusion but the difference was not statistically significant. Infusion of a lipid suspension is unlikely to materially affect the severity of amitriptyline intoxication.

Adult↗

Elimination and pharmacological effects following single oral doses of 50 and 75 mg of amitriptyline in man.

In a companion paper we described the disposition of a 75 mg single dose of amitriptyline in normal volunteers who were phenotyped as extensive or poor metabolizers of debrisoquine and bufuralol, and had a four-fold range in the oral clearance of the antidepressant, 50 mg of amitriptyline was also administered to the same volunteers. This paper compares the results after both doses and suggests that the disposition of amitriptyline is linear even in subjects with a low oral clearance. There was no relation between the pharmacokinetic data and the intensity of sedation or of psychomotor impairment.

Administration, Oral↗

The relationship between changes in REM sleep and clinical improvement in depressed patients treated with amitriptyline.

EEG sleep recordings were obtained on consecutive nights from six hospitalized depressed patients before, during, and after treatment with amitriptyline for a total of 370 nights of data, about 85% of all nights of the study. Amitriptyline significantly reduced time spent in rapid eye movement (REM) sleep and prolonged the REM latency throughout the treatment period. Three patients who improved during treatment showed a REM rebound when amitriptyline was discontinued, whereas three patients who did not improve showed no REM rebound.

Aged↗

Amoxapine and amitriptyline. II. Specificity of cognitive effects during brief treatment of depression.

Cognitive effects of brief antidepressant treatments were studied in depressed outpatients assigned double-blind to equipotent doses of amoxapine or amitriptyline in a 12-week double-crossover of 3-week periods of active agent and placebo. The two drugs had different profiles of effects: amitriptyline was associated with faster reaction time on tests of attention and immediate memory, reduced accuracy on an attention task, and impaired long-term memory (after 1 but not 3 weeks); amoxapine slowed performance and increased intraperson variability on a psychomotor coordination task. Amitriptyline facilitated performance in the more depressed patients, and amoxapine in the older patients. Both agents also increased pulse rate and reduced palmar sweating.

Amitriptyline↗

The relationships between clinical response, psychophysiological variables and plasma levels of amitriptyline and diazepam in neurotic outpatients.

In a 4 week study of the response of neurotic outpatients to treatment with amitriptyline, diazepam, amitriptyline and diazepam, or placebo clinical and psychophysiological variables and plasma levels of the drug were assessed. Clinical improvements were substantial in all treatment groups but clear relationships between clinical change, psychophysiological change and plasma levels of the drugs were not established. There was no relationship between plasma levels of the drugs and cigarette smoking. It is concluded that neither plasma levels of amitriptyline and diazepam nor change in skin conductance responsivity offer a useful guide to clinical response to drug treatment.

Adult↗

Effects of amitriptyline and zimelidine in combination with ethanol.

Six healthy male volunteers took part in this three-period crossover study. In each session, a dose of trial drug -- either placebo, zimelidine 200 mg, or amitriptyline 75 mg -- was given at 09.00 h. Ethanol (50 g) was taken orally at 1200 h. Blood samples were taken for measurement of drug and ethanol concentrations, and body sway and subjective sedation were determined. No differences in the pharmacokinetics of ethanol were seen between the three treatment sessions. Amitriptyline and ethanol showed marked sedative effects, and the results suggest that these two effects may be additive. The combination of amitriptyline and ethanol results in a particularly marked increase in body sway. No sedative nor alerting effect of zimelidine was seen, nor was any interaction between zimelidine and ethanol apparent.

Adult↗

Biotransformation of amitriptyline in depressive patients: urinary excretion of seven metabolites.

The urinary excretion of amitriptyline (AMT) and seven of its metabolites was studied by mass spectrometry in 10 depressive in-patients treated to steady-state condition with oral amitriptyline. An average of 68.3% of the dose was recovered in the urine, of which 68.6% was present as conjugates. Hydroxynortriptyline and its conjugate represented 54% of the total recovery. There was marked variation in metabolite pattern between patients. The variations were not due to concomitant medication with benzodiazepines. There was no correlation between the plasma and urine concentrations of AMT and its metabolites, except for amitriptyline conjugates. Two groups of patients could be distinguished - low and high excretors, who displayed alternative routes of metabolism. The disappearance rate of AMT from plasma was determined by the metabolic clearance of AMT to its metabolites. It varied considerably between patients.

Adult↗