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Plasma concentrations of protriptyline and clinical effects in depressed women.

We studied the relationship between side effects, clinical outcome and the drug plasma levels in 28 female depressed patients treated with protriptyline. After 3 1/2 weeks treatment, patients with plasma levels within a median range (630 to 900 nmol/l) showed better responses to the drug than patients with plasma levels outside this range. There were no statistically signficant correlations between plasma levels and side effect scores or 'corrected' side effect scores (scores after subtracting pretreatment values) for the group at any time after starting the treatment. But we found positive correlations between plasma levels and 'corrected' side effect scores for the neurotic subgroup after 14 and 21 days of treatment. Other correlations between plasma levels and side effect scores were non-significant.

Adjustment Disorders

Epoxide metabolites of protriptyline in rat urine.

Two epoxide metabolites of 5-(3-methylaminopropyl)-5H-dibenzo[a,d]cycloheptene (protriptyline) were identified in the urine of rats given 14-C-labeled drug. They were characterized by mass spectrometry, nuclear magnetic resonance spectrometry, and chemical reactivity as 10,11-dihydro-10,11-epoxy-5(3-methylaminopropyl)-5H-dibenzo[a,d]cycloheptene (I) and 10,11-dihydro-10,11-epoxy-5(3-aminopropyl)-5H-dibenzo[a,d]cycloheptene (II). Over twice as much I as II was excreted and together the two metabolites accounted for approximately 40% of the urinary radioactivity.

Animals

Relationships between chronotropic effect, 1-3H-noradrenaline uptake and tissue concentrations of desipramine, protripyline and doxepin in rat isolated atria.

The pharmacological effects of three tricyclic antidepressant agents (desipramine, protriptyline and doxepin) are evaluated in rat isolated atria in relation to their accumulation and efflux kinetics. The pharmacological effects studed are: inhibition of 1-3H-noradrenaline uptake, potentiation of 1-noradrenaline chronotropic response, and changes in spontaneous atrial rate. All drugs inhibit noradrenaline uptake and potentiate noradrenaline chronotropic response (desipramine congruent to protriptyline greater than doxepin). Desipramine and protriptyline, at concentrations of 10(-7) -- 10(-6)M stimulate the spontaneous rate; higher concentrations (greater than 10(-6)M) depress it. Doxepin has only a negative chronotropic effect. When the drugs are removed from the incubation medium, the depressing effect starts to disappear immediately for doxepin and desipramine and after 20 min for protriptyline. On the contrary the stimulating effect persists after repeatedly washing the preparations. Desipramine, protriptyline and doxepin extensively accumulate in the myocardial tissue (desipramine larger than or equal to protriptyline greater than doxepin). In the efflux studies doxepin is washed out more rapidly than desipramine and protriptyline. Although the kinetics of uptake and efflux of the three compounds are not sufficient to interpret their different pharmacological activities in isolated atria, they give useful information on the persistance of the sympathomimetic effect and the rapid disappearing of the negative chronotropic effect after washing.

Animals

Drowsiness, impaired performance and tricyclic antidepressants drugs.

1. The effects of amitriptyline, protriptyline, protriptyline, and a chemically related potential antidepressant, BW247, on performance tests and subjective ratings were studied. 2. Two groups of twelve healthy subjects received drugs and lactose dummy in identical capsules at weekly intervals according to a balanced design, under double-blind conditions, and with standarized tests and environment. 3. Amitriptyline produced the most marked effects, with significant (P less than 0.05) impairment in auditory vigilance after 6.25 mg. Auditory reaction time, tapping rate, arithmetic, and digit symbol substitutions were impaired by amitriptyline 12.5 and 25 mg and all doses produced increased ratings of mental sedation. The effects began 1.5 h after drug and lasted approximately 5 h. 4. Nortriptyline produced fewer effects which were later in onset. Tapping at 1.8 h and auditory vigilance at 3.5 to 4.5 h were impaired by nortriptyline 25 mg whereas reaction time was prolonged by both doses at 5 h. No change in rating of mental sedation occurred. 5. No significant change in performance or subjective ratings followed protriptyline 10 mg or BW247, 12.5 and 25 mg. 6. The findings are discussed in relation to the presence of secondary and tertiary amines on the side chain of the compounds, and their relative abilities to block neuronal uptake of noradrenaline and 5-hydroxytryptamine.

Acoustic Stimulation

The effect of gamma-butyrolactone on locomotor activity in the rat.

The effect of gamma-butyrolactone (GBL) on locomotor activity in the rat was studied. Low doses of GBL (100 and 200 mg/kg) had a biphasic effect on activity. Initially, the activity of the rats was reduced, and this reduction was then followed by a period of hyperactivity. The effect of alpha-flupenthixol (50 microgram/kg alpha-FPT), atropine (10 mg/kg), benztroine (25 mg/kg), protriptyline (15 mg/kg), and clomipramine (25 mg/kg) was investigated on this biphasic effect. alpha-FPT reduced the hyperactivity while benztropine potentiated it; atropine, clomipramine, and protriptyline had little effect. It is concluded that the increase in activity could be due to a release of dopamine.

4-Butyrolactone

Effects of tricyclic drug on induced circular dichroism spectra of dicumarol bound to alpha 1-acid glycoprotein.

Effects of both tricyclic and non-tricyclic drugs on the extrinsic Cotton effects of dicumarol bound to human alpha 1-acid glycoprotein (AGP) have been investigated. Basic tricyclic drugs caused the reversal of the signs of the induced Cotton effects of the circular dichroism (CD) spectra of the dicumarol-AGP system while the basic drugs not possessing tricyclic rings and acidic drugs decreased the observed ellipticities without changing the signs of its CD spectra. There was no reversal of the CD signs of the drugs not containing two hydroxycoumarin rings bound to AGP by basic tricyclic drugs. Raising of pH and temperature, and the addition of guanidine hydrochloride decreased the observed ellipticities of the CD spectra of the dicumarol-AGP system without showing any change in the signs of the Cotton effects. The mutual displacement data showed that protriptyline increased its own binding and that of dicumarol with AGP. The results of CD titration and equilibrium dialysis experiments suggest that dicumarol-AGP and dicumarol-AGP-protriptyline form a 1:1 binary complex and a 1:1:1 ternary complex, respectively.

Antidepressive Agents, Tricyclic

Serotonergic reduction of dorsal central gray area stimulation-produced aversion.

Stimulating electrodes were implanted into the dorsal central gray area (DCG) of rats. The animals were trained to bar press to decrement the aversive DCG stimulation current. Rats treated with 5-hydroxytryptophan (5-HTP), 75 mg/kg or 150 mg/kg, showed a dose-dependent reduction in decremental bar pressing. In a second study, animals received either chlorimipramine, 15 mg/kg, protriptyline, 15 mg/kg, or 5-HTP, 150 mg/kg. Chlorimipramine, a strong blocker of serotonin reuptake, and 5-HTP produced significant reductions in decremental bar pressing. Protriptyline, a weak serotonin reuptake blocker, produced no significant effect. These results suggest that serotonin reduces aversive neural mechanisms associated with the dorsal central gray area.

5-Hydroxytryptophan

Effect of uptake inhibitors on the depletion of brain norepinephrine and serotonin after alpha-methyl-m-tyrosine administration to rats.

The depletion of brain norepinephrine after alpha-methyl-m-tyrosine injection into rats was antagonized by pretreatment with an uptake inhibitor (protriptyline or chlorimipramine) but was not completely prevented. Administration of protriptyline after alpha-methyl-m-tyrosine injection, at a time when norepinephrine had been depleted, partially reversed the depletion. Serotonin depletion after alpha-methyl-m-tyrosine was not altered by pretreatment with fluoxetine, an inhibitor of uptake into serotonin neurons. Apparently part of the norepinephrine (but not serotonin) depletion occurring after alpha-methyl-m-tyrosine injection is due to the action of amine products that enter the norepinephrine neuron via the membrane uptake pump and whose presence within the nerve terminals is maintained by the uptake pump.

Animals

Intrapatient variability of serial steady-state plasma tricyclic antidepressant concentrations.

Nine or 10 serial steady-state plasma measurements of amitryptyline, desipramine, desmethyldoxepin, doxepin, imipramine, nortriptyline, or protriptyline were made in 23 depressed patients. Each patient was monitored for compliance by pill counts, and sampling time was controlled carefully to determine intrapatient variability of steady-state tricyclic levels on a day-to-day basis. The coefficients of variation during serial sampling of the various ingested drugs were: amitriptyline, 21%; desipramine, 26%; doxepin, 21%; imipramine, 14%; nortriptyline, 13%; and protriptyline, 17%. The therapeutic ranges for the tricyclic antidepressants are relatively wide, so coefficients of variation of these magnitudes indicate that the position of an individual patient in relation to the optimal therapeutic range can be reliably determined on a clinical basis.

Antidepressive Agents, Tricyclic

Tricyclic antidepressants: effects on extinction and fear learning.

Rats trained to run an alley for a food reward were extinguished following injections of different antidepressants. When retested several days later, the animals extinguished following pretreatment with the NE reuptake blocker protriptyline showed faster running speeds than did the other groups. Other rats given electrical shocks following pretreatment with protriptyline avoided the compartment in which they had been shocked less than did animals shocked following pretreatment with other antidepressants. This implies an interferance with some aspect of the learning or consolidation process which is correlated with the degree of NE reuptake blockage. It is hypothesized that NE terminals are deactivated following frustrative nonreward or punishment by the conversion and reuptake of the released NE to an altered extinction molecule.

Animals

Narcolepsy.

Narcolepsy is a neurological condition with a prevalence of up to 1 per 1,000 that is characterized by irresistible bouts of sleep. Associated features include the pathological manifestations of rapid-eye-movement (REM) sleep: cataplexy, sleep paralysis, hypnagogic hallucinations, and abnormal sleep-onset REM periods and disturbed nocturnal sleep. The condition is strongly associated with the HLA-DR2 and DQw1 phenotype. The phenomenology of narcolepsy is discussed, and diagnostic procedures are reviewed. Treatment modalities involving central nervous system stimulants for somnolence and tricyclic drugs for REM-sleep abnormalities are discussed. Sleep laboratory studies on the treatment efficacy of methylphenidate, pemoline, dextroamphetamine, protriptyline, and viloxazine are presented. Data suggest that: (1) methylphenidate and dextroamphetamine objectively improve somnolence; (2) pemoline, at doses up to 112.5 mg, is less effective in controlling somnolence but may improve certain aspects of performance; and (3) protriptyline and viloxazine are effective anticataplectic agents that produce little improvement in somnolence.

Adult

Tricyclic antidepressants in serum by a Clin-ElutTM column extraction and high pressure liquid chromatographic analysis.

We sought a method for routine therapeutic monitoring of serum tricyclic antidepressants (TCAs) which offered good reproducibility, detection limits, linearity, and specificity, and which was simple, rapid, and inexpensive to perform. The method described utilizes Clin-Elut columns (Analytichem International, Inc., Lawndale, CA 90206) to facilitate the extraction. The analysis is by high pressure liquid chromatography (HPLC) with a CN bonded phase column, a mobile phase of acetonitrile/pH 7.0 phosphate/methanol and detection at 210 nm. This chromatographic system gives short equilibration times, stable calibration curves, high sensitivity and resolution, short retention times, and long column life. The method is useful for determination of amitriptyline, doxepin, imipramine, nortriptyline, nordoxepin, desipramine, and protriptyline. Trimipramine is used as an internal standard for the tertiary amines and protriptyline for the secondary amines. Recovery is linear from 25 ato 1,000 ng/ml. Rubber stoppers of a new formulation in Vacutainer blood collection tubes (Becton-Dickinson, Rutherford, NJ 07070) do not affect serum TCA levels. Sera from 53 psychiatric patients suffering from endogenous depression were analyzed using the procedure presented. The mean serum level of four patients on amitriptyline therapy having complete remission was 201 ng/ml (range, 123-259). The mean serum level of four patients on imipramine therapy rated as having complete remission was 200 ng/ml (range, 145-258). These values compare well with recently published therapeutic ranges.

Antidepressive Agents, Tricyclic

Effects of antidepressant drugs on noradrenaline accumulation and contractile responses in the rat anococcygeus muscle.

1 The effect of a series of antidepressant drugs on noradrenaline accumulation was studied in the isolated anococcygeus muscle of the rat. 2 The most potent inhibitors of noradrenaline accumulation were nortriptyline, desipramine and protriptyline. Opipramol, trimipramine and iprindole were active only in high concentrations. 3 Contractions of the anococcygeus muscle produced by noradrenaline were strongly potentiated by nortriptyline, desipramine and protriptyline. Other uptake inhibitors were less active in potentiating the noradrenaline response. 4 Nortriptyline, in concentrations that potentiated the action of noradrenaline, reduced or abolished the response to tyramine.

Acetylcholine

Interaction between centrally acting hypotensive drugs and tricyclic antidepressants.

From clinical experience it is known that the hypotensive action of clonidine and alpha-methyl-DOPA is antagonized by desipramine. This antagonism was investigated in detail in chloralose-anaesthetized cats. Both the centrally acting hypotensive agents and the tricyclic antidepressants where infused into the left vertebral artery. (1) The central hypotensive action clonidine was antagonized by desipramine, imipramine, amitriptyline, protriptyline and mianserine. For the inhibition of the hypotensive action of clonidine by protriptyline a parallel shift of the dose-response curve was obtained, indicating the possibility of a competitive antagonism. The central hypotensive action of alpha-methyl-DOPA was antagonized by desipramine and imipramine and that of amphetamine by imipramine. (2) The modest central hypotensive action of tricyclic antidepressants themselves and that of cocaine is explained by means of the inhibition of noradrenaline re-uptake in the CNS, brought about by these compounds. (3) It seems likely that the antagonism occurs at the level of central alpha-adrenoreceptors in the brain stem. (4) The antagonism probably reflects a general interaction between centrally acting hypotensive drugs and tricylclic antidepressants. The alpha-sympatholytic properties of the tricyclic antidepressants probably give rise to a blockade of the central alpha-adrenoreceptors, stimulated by clonidine, noradrenaline (via amphetamine) and alpha-methylnoradrenaline (from alpha-methyl-DOPA). The cocaine-like activity of antidepressants does not play a part.

Amphetamine

Blockade of amine depletion by nisoxetine in comparison to other uptake inhibitors.

Nisoxetine, 3-(o-methoxyphenoxy)-3-phenyl-N-methyl-propyl-amine, is a new inhibitor of norepinephrine uptake. Nisoxetine antagonized 6-hydroxydopamine-induced depletion of norepinephrine in mouse heart with an ED50 of 0.9 mg/kg but had no effect on p-chloroamphetamine-induced depletion of serotonin in mouse brain at doses up to 32 mg/kg. Using the antagonism of these depleting agents to estimate inhibition of uptake into noradrenergic and serotoninergic neurons, we compared nisoxetine to several known amine uptake inhibitors. The order of effectiveness in antagonizing 6-hydroxydopamine action was protriptyline greater than desmethylimipramine greater than EXP 561 greater than nisoxetine greater than nortriptyline greater than chlorpheniramine greater than desmethylchlorimipramine greater than imipramine greater than doxepin greater than amitriptyline greater than chlorimipramine, with fluoxetine and its N-demethylated metabolite (103947) having no effect. In blocking p-chloroamphetamine, the order of effectiveness was EXP 561 greater than fluoxetine greater than 103947 greater than chlorpheniramine greater than chlorimipramine, with desmethylchlorimipramine, protriptyline, and nortriptyline having marginal effects and nisoxetine and the other drugs no effect at the highest dose tested, 32 mg/kg. Nisoxetine is thus one of the more potent and specific inhibitors of norepinephrine uptake, differing remarkably from fluoxetine to which it is related structurally.

Amines