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Biotransformation of amitriptyline in alcoholic depressive patients.

The biotransformation of amitriptyline (AMT) during steady state conditions was studied in plasma and urine from 11 nonalcoholic and 10 alcoholic depressive inpatients treated with oral AMT. The 2 groups of patients had a different pattern of biotransformation. The Demethylation of AMT was lower in alcoholic than in nonalcoholic depressive patients, and conjugation and hydroxylation of AMT were also more marked in the former group. The results may be of clinical relevance since the conjugates of AMT are inactive.

Adult↗

Age differences in effects on blood pressure, flicker fusion frequency, salivation and pharmacokinetics of single oral doses of dothiepin and amitriptyline.

Blood pressure, critical flicker fusion frequency (CFF), salivary flow rate and pharmacokinetics were compared in 7 young healthy volunteers (average age: 22.7 years) and in 7 elderly healthy volunteers (average age: 70.6 years) after single oral doses of the antidepressants dothiepin (DP) 25 mg and amitriptyline (AMP) 25 mg. Systolic blood pressure fell further and the reduction lasted longer in the elderly than in the young after both drugs. The decrease in CFF after AMP 25 mg, and the reduction in salivary flow rate after either DP 25 mg or AMP 25 mg were larger in the elderly than in the young. Plasma levels, T1/2 and Cl of both drugs in the elderly were also higher, longer and smaller, respectively, in the elderly. Clearance was found to be reduced in the elderly. More cautions dosage regimens of these drug should be considered for elderly patients.

Adult↗

Psychomotor, respiratory and neuroendocrinological effects of buprenorphine and amitriptyline in healthy volunteers.

Actions and interactions of buprenorphine (BUP) and amitriptyline (AMI) on performance and respiration were studied double-blind and cross-over in 12 healthy volunteers. After one-week pretreatments with AMI or placebo, the subjects received on Day 8 placebo, BUP or AMI so that the final treatments were 1) placebo, 2) acute AMI 50 mg, 3) acute BUP, 4) subchronic AMI + acute BUP and 5) subchronic AMI. The subacute treatments were started at two-week intervals. A Mapleson D rebreathing circuit including a pneumotachograph and an infrared capnograph was employed to study drug effects on respiration. Minute volume and end-tidal carbon dioxide as well as psychomotor performance were measured and the blood samples taken on Day 8 before the drug intake and 2 and 4 h thereafter. The performance tests included tracking, choice reaction, flicker fusion, exophoria, nystagmus, digit symbol substitution and the subjective assessment of mood. BUP depressed respiration, and subchronic AMI increased this depression. Both BUP and acute AMI 50 mg each alone impaired various measures of performance and rendered the subjects drowsy, feeble, mentally slow and muzzy but subchronic AMI did not enhance BUP effects. BUP increased plasma prolactin levels similarly after both pretreatments. The results suggest that both BUP and AMI moderately affect psychomotor performance but the interaction between these agents is mild and restricted mainly to respiration.

Adult↗

Plasma protein binding of perazine and amitriptyline in psychiatric patients.

The free fraction of amitriptyline (AT), measured by equilibrium dialysis in plasma from 29 AT-treated depressed patients, was 5.4-9.8% (mean 7.7%), which was the same as the values in 26 healthy controls (4.9-9.6%, mean 7.6%). The plasma levels of lipoproteins, as reflected by total cholesterol, and of alpha 1-acid glycoprotein (alpha 1-AGP) did not differ between the two groups. the free fraction of AT in both exhibited a significant negative correlation with the concentrations of those two proteins. The unbound fraction of perazine (PER) was the same (3.1-5.9%, mean 4.4%) in plasma from 22 schizophrenic patients and from 24 healthy volunteers (2.9-6.0%, mean 4.5%). However, in patient plasma alpha 1-AGP was significantly higher (mean 1.07 vs 0.81 mg/ml) and total cholesterol tended to be lower (mean 173 vs 201 mg/100 ml) than in plasma from normals. In consequence, the free fraction of PER was negatively correlated with the alpha 1-AGP concentration in plasma from patients and with the cholesterol level in plasma from control subjects; the other correlations were not significant. In 7 patients, the alpha 1-AGP level was normal prior to Per treatment. Serial blood samples from 6 patients revealed a consistent elevation of alpha 1-AGP above its pretreatment level during 4 weeks of PER administration in 5 of the subjects and a transient increase in one other. while low lipoprotein levels in schizophrenics seem to be a disease-related trait, the increase of alpha 1-AGP may be a drug effect.

Adolescent↗

Prolactin, amitriptyline, and recovery from depression.

Spontaneous prolactin patterns were determined at 15-min intervals over 5 h in 13 patients, who were suffering from melancholia, during illness and after treatment with amitriptyline. Plasma prolactin levels were significantly greater at most sampling points after patients had recovered than during their illnesses. One patient, who did not recover, showed the opposite trend.

Adult↗

Parenteral pentazocine: effects on psychomotor skills and respiration, and interactions with amitriptyline.

The combined effects on performance and respiration of pentazocine (PZ) and amitriptyline (AMI) were evaluated in a double-blind cross-over study in 11 healthy students. After pretreatment for 1 week with AMI or placebo, on Day 8 the subjects received placebo or 50 mg p.o. AMI and 30 mg PZ or saline i.m. so that the final treatments were 1) placebo, 2) acute AMI 50 mg, 3) acute PZ, 4) subchronic AMI + acute PZ and 5) subchronic AMI. The subacute treatments were started at two-week intervals. Objective and subjective performance tests and respiratory function (minute volume, ETCO2) were measured. Parenteral PZ impaired sensory processing (digit symbol substitution, choice reactions) and extraocular muscle balance (Maddox wing) but left motor skills (tracking, tapping speed) unaffected. A single oral dose of AMI 50 mg affected both sensory and motor performance. The psychomotor effects of PZ were clearest at 1.5 h, and those of AMI at 3.5 h. Both drugs rendered the subjects drowsy, clumsy, and muzzy on visual analogue scales, but PZ also induced positive feelings, like contentedness and friendliness. PZ depressed respiration in terms of lowered minute volume and elevated ETCO2, and subchronic AMI increased this depression. The chemically assayed plasma concentrations of AMI and PZ were as expected; radioreceptor assay revealed low or negligible mu-opiate activity in plasma after PZ. The results suggest that AMI does not enhance the moderate psychomotor decrement produced by PZ. However, respiratory depression may be increased by their concomitant use.

Adult↗

Amitriptyline: linear or nonlinear kinetics in every day practice?

The linearity of the (AMT) kinetics of amitriptyline has been tested in 135 depressed dosed twice daily by measuring plasma. Their (AMT) and nortriptyline (NT) levels under steady-state conditions. The AMT concentration/dose ratios at low and high dosages were not significantly different and there was a linear relationship between the dose ratios and the concentration ratios. No change in the metabolic ratio (AMT/NT) was observed between the two dosages. Although the results are consistent with linear AMT kinetics, there may have been nonlinear kinetics in some patients as the ratio between the concentration/dose ratios in them at low and high dosages was greater than one. Those patients were characterized by a low concentration/dose ratio at low dosage. No clinical adverse effect appeared in the study.

Amitriptyline↗

Metabolism of amitriptyline in patients with chronic renal failure.

The metabolism of amitriptyline (AMT) has been studied in two groups of depressed in-patients on long term AMT therapy: 11 patients with no other major disease and 8 patients with chronic renal failure, who were being dialysed. The patients with renal insufficiency had decreased concentrations of AMT, nortriptyline (NT) and their unconjugated hydroxymetabolites compared to patients with normal kidney function. The plasma levels of conjugated products were extremely high in the uraemics. The latter metabolites are probably inert. The reduced concentration of unconjugated hydroxymetabolites , which are active compounds, may decrease the clinical effectiveness of the drug.

Adult↗

5-HT1A receptor function in depression: effect of chronic amitriptyline treatment.

Hypothermic responses to 5-HT1A receptor activation by the selective ligand ipsapirone (IPS) were attenuated in depressed patients as compared to controls. Chronic treatment with amitriptyline (AMI) further impaired 5-HT1A-mediated hypothermia. The results indicate a subsensitive (presynaptic) 5-HT1A receptor and/or a defective post-receptor signalling pathway in depression and are consistent with the hypothesis that 5-HT1A receptors are down-regulated during AMI treatment.

Adult↗

Aspects of amitriptyline and nortriptyline plasma levels monitoring in depression.

Fifty-nine depressed female inpatients were treated with 100 mg amitriptyline (AMT) IM for 4 weeks. Depression ratings and determinations of the parent drug and nortriptyline (NT) were performed weekly. No direct relationship between plasma AMT + NT concentrations and therapeutic response was apparent, but beneficial therapeutic responses and significantly lower side-effect scores were more frequently noted in subjects with concentrations in the 100-200 ng/ml range. AMT + NT concentrations were significantly correlated with age. No significant difference was found in the number of responders between younger and older subjects with two clinical improvement criteria; however, a significant difference emerged when a third more restrictive clinical outcome criterion was adopted. The implications of the present findings for patient treatment and for the interpretation of previous studies are discussed. The data collected point to a possible usefulness of monitoring AMT and NT plasma levels, even if further investigations are needed.

Adult↗

Urinary metabolites of amitriptylinoxide and amitriptyline in single-dose experiments and during continuous therapy.

In a cross-over design, six healthy volunteers received 50 mg amitriptylinoxide (AT-NO) IV and orally and 50 mg amitriptyline (AT) IV. Urine was collected completely for 8 h and occasionally up to 48 h. In addition, five patients each under treatment with AT-NO or AT for tension headache collected 24-h urine samples. The following compounds were analysed by HPLC: AT-NO, E- and Z-10-hydroxy-AT-NO (E- and Z-10-OH-AT-NO), free and conjugated AT, E- and Z-10-OH-AT and their mono- and didemethylated analogues, and 2-OH-nortriptyline (2-OH-NT). Unchanged AT-NO in urine accounted for an average of 34% and 22% of the single IV and oral doses, respectively, and for 28% in continuous therapy, with a further 8-9% being excreted as E- and Z-10-OH-AT-NO. The remaining part was converted to the same metabolites as was AT. In the steady state the measured compounds accounted for 74% and 77% of the daily AT-NO and AT doses, respectively. The renal plasma clearance of AT-NO varied between 75 and 265 ml/min in the six volunteers. Tubular secretion must play an important part in the renal excretion of AT-NO.

Adult↗

Average parameters in bioavailability studies: an application to slow-release amitriptyline formulation.

In order to assess the extent and the rate of absorption in bioavailability studies, area under the curve (AUC), experimental maximum concentration (Cmax) and experimental time to reach Cmax (Tmax), are used. But when slow-release formulations are considered, the drug concentration-time curves usually show multiple peaks, and it is difficult to compute a Cmax and Tmax value. In case a Cmax value is computed, important variability in this parameter results in high values in the residual variance of the ANOVA test. So in order to decrease the high variability, average parameters: average concentration (Cav), average maximum concentration (Cmax,av) and Cmax,av x 100/Cav (%Cmax,av), are proposed. These new parameters were applied in a bioavailability study of slow-release amitriptyline formulation.

Adult↗

Clinical response and plasma concentrations of amitriptyline and its metabolite-nortriptyline in depressive patients.

Although many attempts have been made, to date no convincing evidence exists of a relationship between plasma concentrations of amitriptyline (AT), its active metabolite nortriptyline (NT) and clinical response. Fifteen patients with primary depression (according to DSM-IV) were divided in two groups according to given doses: (I) 6 patients received 3 x 50 mg of AT daily; and (II) 9 patients received 3 x 25 mg of AT daily, for 6 weeks. The clinical status was determined with Hamilton Depression Rating Scale. Both investigated doses were therapeutically effective. AT and NT plasma concentrations were assayed by high performance liquid chromatography. Following administration of 3 x 50 mg of AT daily, the correlation of concentrations of AT, NT, total AT + NT and clinical response were rAT = -0.702 (P < 0.1), rNT = -0.761 (P < 0.1), rAT + NT = -0.741 (P < 0.1). The linear and very high correlation were also present with concentrations of AT, NT, total AT + NT and clinical response in depressive patients on 3 x 25 mg AT daily: rAT = -0.785 (P < 0.02), rNT = -0.811 (P < 0.01), rAT + NT = -0.848 (P < 0.01). Our results support a high correlation between AT/NT plasma concentrations and clinical response indicating that therapeutic monitoring of AT and its metabolite, NT, can provide eventual clinical response.

Adult↗

[Drug-induced headache and pain reduction medication with amitriptyline in an 11-year old pupil].

We report on an 11-year-old pupil who present-ed to a neurological practice in the company of his parents because of migraine and strong headaches. Precise anamnesis of drugs yielded the diagnosis of a drug-induced headache with underlying migraine disease. The boy was afflict-ed with a hereditary taint, as both parents also suffered from migraine. The mother was also continuously in treatment because of a chronic pain disorder. Therapy with up to 50 mg per day of amitriptyline enabled the boy to stop consuming analgesics without suffering from head-aches. Moreover, under 47.5 mg per day of metoprolol, the migraine symptoms did not re-occur.

Amitriptyline↗

Sex differences in response to oral amitriptyline in three animal models of depression in C57BL/6J mice.

RATIONALE: Knockout and transgenic mice provide a tool for assessing the mechanisms of action of antidepressants. The effectiveness of oral administration of the tricyclic antidepressant amitriptyline (AMI) was assessed in C57BL/6J (B6) mice, a common genetic background on which knockout and transgenic mice are maintained. OBJECTIVES: We determined whether oral AMI would have antidepressant-like effects in B6 mice and whether these effects varied according to sex, duration of treatment, and the depression model utilized. METHODS: Male and female B6 mice were administered AMI (200 microg/ml) in the drinking water as the sole source of fluid, along with 2% saccharin to increase palatability. Control mice were administered 2% saccharin alone. Mice were assessed for responsiveness to AMI in the tail suspension test (TST), the forced swim test (FST), and the learned helplessness (LH) paradigm. RESULTS: In the TST, AMI decreased immobility time regardless of sex or duration of treatment. AMI also decreased immobility time in the FST, but chronic treatment was necessary for full efficacy in both sexes. In the LH paradigm, both subchronic and chronic AMI treatment decreased escape latencies in female mice, but AMI was effective only after chronic treatment in males. The antidepressant-like effects of AMI could not be explained by differences in locomotor activity because activity levels were not altered by antidepressant treatment. CONCLUSIONS: Overall, oral AMI administration provides a valid model for behavioral assessment of antidepressant-like effects in knockout and transgenic mice maintained on a B6 background, but the effectiveness of oral AMI varies depending on sex, duration of treatment, and the depression model used.

Administration, Oral↗

Transplacental transfer of amitriptyline and nortriptyline in isolated perfused human placenta.

RATIONALE: Although tricyclic antidepressants (TCAs) have gained wide acceptance for use in the treatment of depression in pregnant women, their pharmacokinetics during pregnancy have been poorly characterized. The aim of the present study was to investigate the transplacental transfer of amitriptyline (AMI) and its main active metabolite nortriptyline (NOR) in isolated perfused human placenta. METHODS: Nine term human placentae were obtained immediately after delivery with maternal consent and a 2-h non-recirculating perfusion of a single placental cotyledon was performed. AMI (200 ng/ml) and NOR (150 ng/ml), with antipyrine as a reference compound, were added to the maternal reservoir and their appearance to the fetal circulation was followed for 2 h. AMI and NOR concentrations were measured by high performance liquid chromatography (HPLC) and antipyrine concentrations spectrophotometrically. RESULTS: The mean (SD) transplacental transfers (TPT(SS)%) for AMI and NOR were 8.2 (2.3)% and 6.5 (1.8)%, respectively, calculated as the ratio between the steady-state concentrations in fetal venous and maternal arterial sides. The TPTs of AMI and NOR were 81% and 62% of the freely diffusable antipyrine. The absolute fraction of the dose that crossed the placenta (TPT(A)) was moderately, but significantly higher for AMI (7.7%) than for NOR (5.7%) (P=0.037). In all perfusions, steady state at the fetal side was reached by 30 min for AMI and by 50 min for NOR in the fetal side. The viability of the placentae was retained during the 2-h perfusion, as evidenced by unchanged pH of the perfusate and by stable perfusion pressures in fetal artery and stable antipyrine transfer. CONCLUSIONS: Both AMI and NOR cross the human placenta. However, the fetal exposure with NOR may be somewhat smaller compared with AMI, probably due to the higher lipophilicity of AMI.

Adult↗

The role of CYP2C19 in amitriptyline N-demethylation in Chinese subjects.

OBJECTIVE: To determine the role of cytochrome P(450) (CYP)2C19 in N-demethylation of amitriptyline (AT) in healthy Chinese subjects. METHODS: One hundred and one subjects were genotyped for CYP2C19 using polymerase chain reaction-restriction fragment length polymorphism analysis. Twelve unrelated adult men (19.7+/-0.6 years, 61.8+/-3.8 kg) were chosen and orally given a single dose of 50 mg AT, and the blood samples were drawn from a forearm vein at 0.5, 1, 2, 3, 4, 5, 6, 8, 10, 12, 24, 48, 72, and 96 h after AT administration. Plasma concentrations of AT and nortriptyline (NT) were determined using high-performance liquid chromatography with an ultraviolet detector. RESULTS: The mean area under the plasma concentration-time curve (AUC(AT)) of CYP2C19 poor metabolizers (PMs, n=6) was significantly higher than that of CYP2C19 extensive metabolizers (EMs, n=6) (2207+/-501 ng/ml x h(-1) vs 1596+/-406 ng/ml x h(-1), P<0.05). In contrast, the mean AUC(NT(0-)(infinity)()) of PMs was significantly lower than that of EMs (294+/-70 ng/ml x h(-1) vs 684+/-130 ng/ml x h(-1), P<0.0001). Other pharmacokinetic parameters such as clearance, half-life, maximum plasma concentration, and time to peak plasma concentration showed no significant difference between PMs and EMs (0.41+/-0.12 l /h x kg(-1) vs 0.50+/-0.15 l /h x kg(-1), 25.0+/-6.2 h vs 24.1+/-4.4 h, 96+/-25 ng/ml vs 75+/-27 ng/ml, 4.0+/-1.4 h vs 3.7+/-1.5 h, respectively). CONCLUSION: The genetic defects of CYP2C19 have a significant effect on AT pharmacokinetics, and CYP2C19 plays an important role in N-demethylation of AT in vivo at a clinically therapeutic dose.

Administration, Oral↗

A case of predominantly nocturnal soiling treated with amitriptyline.

The case of a 6 year old with soiling along with looseness of bowel and nocturnal soiling is reported. After failing to respond to conventional treatments, his symptoms remitted on a small dose of amitriptyline. Within the diversity of presentations of soiling, there may be a subgroup, not usually amenable to treatment, who can benefit from symptomatic treatment with tricyclic antidepressants.

Amitriptyline↗