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PubMedDate not supplied

Influence of classic and atypical neuroleptics on caffeine oxidation in rat liver microsomes.

Caffeine is a marker drug for testing the activity of CYP1A2 (3-N-demethylation) in humans and rats. Moreover, CYP3A seems to be essential for its metabolism (8-hydroxylation). In the case of 1-N- and, in particular, 7-N-demethylation of caffeine, apart from CYP1A2, other CYP isoenzymes play a considerable role, probably CYP2B and/or CYP2E1. The aim of the present study was to investigate the influence of two classic neuroleptics (promazine and haloperidol) and two atypical ones (risperidone and sertindole) on cytochrome P-450 activity measured by caffeine oxidation in rat liver microsomes. The obtained results showed that promazine, a phenothiazine neuroleptic with the simplest chemical structure, significantly inhibited 1-N- and 3-N-demethylation and 8-hydroxylation of caffeine via competitive or mixed mechanism (Ki = 21.8, 25.4 and 58.2 microM, respectively). This indicates inhibition by promazine of CYP1A2 (inhibition of 3-N- and 1-N-demethylation), and possibly CYP3A2 (inhibition of 8-hydroxylation), but not of other CYP isoenzymes involved in 7-N-demethylation of caffeine (e.g. CYP2B2 and/or CYP2E1). In contrast to promazine, haloperidol had no effect on the oxidation reactions of caffeine in the applied in vitro metabolic model. The potency of inhibition of caffeine oxidation by risperidone and sertindole resembled rather haloperidol than promazine. Risperidone appeared to be a very weak inhibitor of 3-N-demethylation and 8-hydroxylation (Ki = 202.5 microM) and had no effect on 1-N- and 7-N-demethylation of caffeine. Sertindole was a very poor inhibitor of 1-N- and 7-N-demethylations and 8-hydroxylation pathways of the marker substance (Ki = 132.1, 434.1 and 173.3 microM, respectively); even the observed in vitro inhibition of 3-N-demethylation of caffeine by sertindole (Ki = 68.9 microM) cannot be of practical significance in vivo, considering extremely low pharmacological and therapeutic doses of the neuroleptic. In summary, among the investigated neuroleptics, only promazine showed significant inhibitory activity towards caffeine metabolism in vitro (inhibition of CYP1A2 and possibly CYP3A), which may be of pharmacological and clinical importance in vivo. In contrast to promazine, haloperidol and the investigated atypical neuroleptics had no or very weak effect on caffeine oxidation in vitro,of no in vivo significance. Considering the results of the present and previous studies, it seems highly likely that promazine may cause pharmacokinetic interactions, while atypical neuroleptics seem to be safe in this respect. Moreover, the observed reaction-dependent effects of promazine and sertindole provide indirect evidence that CYP1A2 is not the only isoenzyme important for the metabolism of caffeine, which requires further pharmacological and clinical consideration.

Animals↗
PubMed2002

The contribution of cytochrome P-450 isoenzymes to the metabolism of phenothiazine neuroleptics.

The aim of the present study was to determine optimum conditions for studying promazine and perazine metabolism in rat liver microsomes, and to investigate the influence of specific cytochrome P-450 inhibitors on 5-sulfoxidation and N-demethylation of these neuroleptics. Based on the developed method, the metabolism of neuroleptics in liver microsomes was studied at linear dependence of product formation on time, and protein and substrate concentrations (incubation time: 10 min; concentration of microsomal proteins: promazine-0.7 mg ml(-1), perazine-0.5 mg ml(-1); substrate concentrations: promazine-25, 40 and 75 nmol ml(-1), perazine-20, 35, 50 nmol ml(-1)). A Dixon analysis of the metabolism of neuroleptics showed that quinine (a CYP2D1 inhibitor), metyrapone (a CYP2B1/B2 inhibitor) and alpha-naphthoflavone (a CYP1A1/2 inhibitor) affected, whereas erythromycin (a CYP3A inhibitor) and sulfaphenazole (a CYP2C inhibitor) did not change the neuroleptic biotransformation. N-Demethylation of promazine was competitively inhibited by quinine (K(i)=20 microM) and metyrapone (K(i)=83 microM), while that of perazine-by quinine (K(i)=46.5 microM), metyrapone (K(i)=46 microM) and alpha-naphthoflavone (K(i)=78.8 microM). 5-Sulfoxidation of promazine was inhibited only by quinine (K(i)=28.6 microM), whereas that of perazine-by quinine (K(i)=10 microM) and metyrapone (K(i)=96 microM). The results obtained are compared with our previous findings of analogous experiments concerning thioridazine, and with the data on other phenothiazines and species. In summary, it is proposed that N-demethylation of the mentioned phenothiazine neuroleptics in the rat is catalyzed by the isoenzymes CYP2D1, CYP2B2 and CYP1A2 (CYP1A2 does not refer to promazine). 5-Sulfoxidation of these drugs may be mediated by different isoenzymes, e.g. CYP2D1 (promazine and perazine), CYP2B2 (perazine) and CYP1A2 (thioridazine). Isoenzymes belonging to subfamilies CYP2C and CYP3A do not seem to be involved in the metabolism of the investigated neuroleptics in the rat. The results obtained point to the drug structure and species differences in the contribution of cytochrome P-450 isoenzymes to the metabolism of phenothiazines.

Alcohol Oxidoreductases↗
PubMed1997

Oxidation of phenothiazines by human term placental peroxidase in non-smokers.

Several phenothiazine derivatives have been shown to cause reproductive toxicity. The biochemical mechanisms responsible for these effects are not fully understood at present. In this study, we investigated hydrogen peroxide-dependent oxidation of seven phenothiazines by purified human term placental peroxidase. Promazine was employed as the prototype phenothiazine drug. Promazine was easily oxidized to a cation radical (absorption maximum at 513 nm) when incubated under acidic conditions with human term placental peroxidase in the presence of hydrogen peroxide. The rate of the radical formation was 350 +/- 30 nmol/min/mg protein when 30 micrograms of the purified peroxidase was incubated with 10 mM promazine and 1.0 mM hydrogen peroxide in acetate buffer pH 3.5. The reaction was linear with respect to time, exhibited dependence on the amount of enzyme, and the concentration of promazine and hydrogen peroxide. Collectively, the results suggest an enzymatic nature of the reaction. Reduced glutathione, ascorbate, and NADH suppressed the rate of promazine radical formation presumably by its reduction back to promazine in a concentration-dependent manner. Concomitantly, NADH was co-oxidized. The cation radical formation and NADH oxidation declined significantly by potassium cyanide and sodium azide, the known peroxidase inhibitors. The enzyme also oxidized chlorpromazine, triflupromazine, trifluoperazine, trimeprazine, fluphenazine, and perphenazine in the presence of hydrogen peroxide. The evidence gathered in this study suggests that peroxidative bioactivation of phenothiazines to their corresponding cation radical species by the human placental peroxidase may represent one of the biochemical mechanisms responsible for the reported developmental toxicity of these chemicals.

Antipsychotic Agents↗
PubMed2004

Comparison of the efficacy of new and conventional antipsychotic drugs in the treatment of behavioral and psychological symptoms of dementia (BPSD).

This double-blind study evaluated the efficacy and safety of risperidone or olanzapine vs. promazine in the treatment of behavioral and psychological symptoms in dementia(BPSD). Patients were required to be 65 years or older, to have DSM-IV diagnoses of Alzheimer's disease (AD), vascular dementia (VD) or a combination of both. A brain computerized tomography (CT) was performed for all the patients; 60 demented patients,27 men (45 %) and 33 women (55 %) were selected for this study. The University of California Los Angeles neuropsychiatric inventory (NPI) was administered at baseline, then after 4 and 8 weeks. Patients had at least a score of 24 or more. The Hoehn and Yahr scale was used for evaluating parkinsonism. The scales were administered by an examinator who was not aware of the kind of treatment of the patients. After a wash-out period of 10 days,20 patients, 9 men and 11 women, mean age 76.6 +/- 6.0 years, were randomly assigned torisperidone 1 mg daily in divided doses (morning and bedtime) (Group A); 20 patients, 9 men and 11 women, mean age 82.5 +/- 9.3 years were randomly assigned to olanzapine 5mg at bedtime (Group B), and 20 patients, 9 men and 11 women, mean age 77.6 +/- 4.6 years, were randomly assigned to promazine 50 mg daily (morning and bedtime) (Group C). In case of lack of clinical response, after 4 weeks, the dose could be increased to 2 mg/day of risperidone, 10 mg/day of olanzapine, and to 100 mg/day of promazine in the respective groups. Repeated measures ANOVA was used for the statistical analysis of rating scales over time (baseline, 4 and 8 weeks). At the end of the 8th week, a global improvement was obtained in 80% of patients treated with risperidone and olanzapine, vs. 65 % of patients treated with promazine (p < 0.01). The results show that risperidone in doses of 1-2 mg/day and olanzapine in doses of 5-10 mg/day are effective and safe in the treatment of BPSD. Risperidone presents a major and dose-dependent antidopaminergic action and seems to be preferable when hallucinations and delusions are prevailing symptoms, even if it gives good results on aggression and wandering. Olanzapine seems to be faster in its sedative effect, probably for H1 receptor blockade. Moreover, 5-HT6 antagonism may favor acetylcholine release and this explains why these patients have not presented a cognitive worsening. However, both drugs are comparable or even superior to promazine, with significantly fewer side effects of both anticholinergic and extrapyramidal character.

Aged↗
PubMed1983

Comparison of the effects of antipsychotic drugs on the schedule-controlled behavior of squirrel monkeys and pigeons.

Lever pressing by squirrel monkeys and key pecking by pigeons were maintained under a multiple 3-min fixed-interval (FI), 30-response fixed-ratio (FR) schedule by the presentation of food. These responses, which differed under the two schedules, but were similar for both species, were used to compare the effects of antipsychotic compounds from different pharmacological classes. Except for differences in potency levels, the effects of intermediate doses of haloperidol and molindone were similar in monkeys and pigeons; these compounds decreased responding under the fixed-interval schedule at doses that did not affect fixed-ratio responding. Similar effects also occurred with chlorpromazine, promazine and thiothixene in pigeons. With monkeys, however, intermediate doses of promazine decreased fixed-ratio responding more than responding maintained under the fixed-interval schedule, while chlorpromazine and thiothixene produced similar effects on responding under both schedules. The effects of novel antipsychotic, clozapine, differed from those of the other agents in both monkeys and pigeons. With both species clozapine increased fixed interval responding at doses that did not affect responding under the fixed-ratio schedule. Doses required to reduce responding at least 50% were approximately 5 to 160 times greater for pigeons than for monkeys for all drugs except clozapine which was equipotent in both species. In monkeys the order of potency was haloperidol greater than molindone = thiothixene greater than chlorpromazine greater than clozapine greater than promazine, whereas in pigeons the order was haloperidol greater than thiothixene greater than clozapine greater than molindone greater than promazine greater than chlorpromazine.

Animals↗
PubMed1997

Contribution of lysosomal trapping to the total tissue uptake of psychotropic drugs.

The present study was aimed at assessing individual contributions of the phospholipid binding and lysosomal trapping to the total tissue uptake of psychotropic drugs with different chemical structures, such as promazine, imipramine, amitriptyline, fluoxetine, sertraline (basic lipophilic drugs) and carbamazepine (lipophilic, but not basic). We also tried to find out whether lysosomal trapping may be involved in the pharmacokinetic interactions in clinical combinations of psychotropics. Uptake experiments were carried out on slices of various rat tissues as a system with intact lysosomes. Initial concentration of each drug was 5 microM. The results were compared with those obtained in the presence of the "lysosomal inhibitors", ammonium chloride or monensin. The basic lipophilic psychotropics showed high uptake in tissues known for the abundance of lysosomes, mainly the lungs. The highest drug accumulation was found for promazine and amitriptyline. "Lysosomal inhibitors" significantly decreased the uptake of the basic lipophilic drugs, particularly in the lungs and liver. The most potent effect was observed for amitriptyline, imipramine and promazine. The brain showed moderate accumulation of basic lipophilic psychotropics and the effect of the "lysosomal inhibitors" was significant only in the case of amitriptyline, imipramine and sertraline. The only exception to the above regularity were imipramine and sertraline which were taken up more extensively by the adipose tissue than by lysosome-rich tissues such as the lungs or liver. Carbamazepine did not show lysosomotropism. Amitriptyline and promazine mutually decreased their uptake by lung slices when the drugs were incubated jointly. In the presence of ammonium chloride the interaction did not occur. In conclusion, the obtained results show that (1) the lysosomal trapping is an important factor determining the distribution of the basic lipophilic psychotropics; however (2) their tissue uptake depends more on the phospholipid binding than on the lysosomal trapping; (3) the lysosomal trapping may be involved in the pharmacokinetic interactions between psychotropics.

1-Naphthylamine↗
PubMed1985

[Premedication and risks in computed tomography of newborn and infant children].

In very young pediatric patients CT-investigations require sedative-hypnotic drug treatment to ensure complete immobilisation during scanning. The case report of a neonate with respiratory arrest after a repeated CT-premedication underlines the high risk of these procedures, especially in patients with central nervous system disorders. We compared organisational requirements, risks and complication rates of 146 oral and intramuscular promazine medications for CT-scanning of the head in 146 infants and neonates (93.8% adequate sedation response) to those of reported alternative methods. Oral promazine proved to be a very effective and safe medication (average dosage in 57 patients without complications: 5.2 mg/kg body weight/90 minutes before CT-scanning; 96% successful sedation procedures) in comparison to 89 patients with i.m. promazine (average dosage: 2.3 mg/kg body weight/45 min before CT with 92% adequate sedations but a complication rate of 7.9%). For neuropediatric examinations of outpatients fast recovery and EEG-compatibility are further important advantages of oral promazine CT-medication.

Head↗
PubMed1980

Conformationally restricted phenothiazine neuroleptics. 1. 3-(Dimethylamino)-1,2,3,4-tetrahydroazepino[3,2,1-kl]phenothiazine.

A rigid analogue of promazine, 3-(dimethylamino)-1,2,3,4-tetrahydroazepino[3,2,1-kl]phenothiazine (1), was prepared by reductive amination of the corresponding ketone 4. An X-ray crystallographic study revealed that the seven-membered ring of the hydrochloride salt of 1 exists as a half-chair-like form with the dimethylammonium group in an equatorial-like conformation. Compound 1 was approximately one-half as active as promazine as an inhibitor of [3H]spiperone binding in rat corpus striatal homogenates. In homogenates obtained from calf caudate tissue, however, 1 was only about one-twentieth as active as promazine as an inhibitor of [3H] spiperone binding. As a stimulator of homovanilic acid (HVA) synthesis in rat corpus striatum in vivo, it was about one-tenth as active as promazine.

Animals↗
PubMed2003

Phenothiazine radicals inactivate Trypanosoma cruzi dihydrolipoamide dehydrogenase: enzyme protection by radical scavengers.

Phenothiazine cation radicals (PTZ+*) irreversibly inactivated Trypanosoma cruzi dihydrolipoamide dehydrogenase (LADH). These radicals were obtained by phenothiazine (PTZ) peroxidation with myeloperoxidase (MPO) or horseradish peroxidase (HRP/H2O2) systems. LADH inactivation depended on PTZ structure and incubation time. After 10 min incubation of LADH with the MPO-dependent systems, promazine, trimeprazine and thioridazine were the most effective; after 30 min incubation, chlorpromazine, prochlorperazine and promethazine were similarly effective. HRP-dependent systems were equally or more effective than the corresponding MPO-dependent ones. Chloro, trifluoro, propionyl and nitrile groups at position 2 of the PTZ ring significantly decreased molecular activity, specially with the MPO/H2O2 systems. Comparison of inactivation values for LADH and T. cruzi trypanothione reductase demonstrated a greater sensitivity of LADH to chlorpromazine and perphenazine and a 10-fold lower sensitivity to promazine, thioridazine and trimeprazine. Alkylamino, alkyl-piperidinyl or alkyl-piperazinyl groups at position 10 modulated PTZ activity to a limited degree. Production of PTZ+* radicals was demonstrated by optical and ESR spectroscopy methods. PTZ+* radicals stability depended on their structure as demonstrated by promazine and thioridazine radicals. Thiol compounds such as GSH and N-acetylcysteine, L-tyrosine, L-tryptophan, the corresponding peptides, ascorbate and Trolox, prevented LADH inactivation by the MPO/H2O2/thioridazine system, in close agreement with their action as PTZ+* scavengers. NADH (not NAD+) produced transient protection of LADH against thioridazine and promazine radicals, the protection kinetics being affected by the relatively fast rate of NADH oxidation by these radicals. The role of the observed effects of PTZ radicals for PTZ cytotoxicity is discussed.

Amino Acids↗
PubMed1962

Poisoning by organic phosphorus pesticides potentiated by phenothiazine derivatives.

Repeated administration of the phenothiazine derivatives chlorpromazine and promazine increased the toxicity of a single dose of parathion in male rats. In female rats, a single dose of 5 mg/kg of promazine increased the toxicity of a single dose of parathion, but had no apparent effect on the toxicity of a single dose of Phosdrin. Repeated dosage with chlorpromazine and atropine, or promazine and atropine, after administration of parathion at the same rate, resulted in a slightly higher mortality in female rats than did atropine or no treatment.

Animals↗
PubMed1990

A third, "deep," compartment for phenothiazine drug disposition: a new look at an old problem.

Volunteers were given oral promazine doses, and blood and urine were collected for promazine assay for as long as was necessary for the drug to cease to be detectable. Postabsorption data were subjected to two- and three-compartment modeling. Renal clearance was calculated. Renal excretion data were analyzed by use of the sigma-minus method, which permits the calculation of the half-life in plasma from excretion data. The mean alpha-phase rate constant for plasma decay (plasma assays) was .0155 min-1. The mean beta-phase rate constant for plasma decay (plasma assays) was .0046 min-1; the mean beta-phase rate constant for plasma decay (urine assays) was .0056 min-1. The mean gamma-phase rate constant for plasma decay (urine assays) was .00075 min-1. These data demonstrate the existence of a third, deep, distribution compartment from which promazine is released slowly and which is only detectable by means of excretion studies.

Humans↗
PubMed2006

A kinetic study on the phenothiazine dependent oxidation of NADH by bovine ceruloplasmin.

Tranquillizing drugs of the phenothiazine class form charge-transfer complexes with a ceruloplasmin-Cu(II) ion [De Mol NJ. 1985 Biochim Pharmacol 34, 2605-2609], the interaction resulting in a stimulatory effect on the ceruloplasmin catalyzed oxidation of catecholamines and NADH; the latter used as substrate in the present study. A good correlation between stability of the enzyme-drug complex and electron donor ability of the phenothiazine molecule was obtained for drugs with an aliphatic propyl side chain in 10-position (promazine > chlorpromazine > triflupromazine). The hydrofobic methyl group in the side chain of levomepromazine appeared to reduce the stability. A simple correlation between specific efficiency of the enzyme-drug complex and electron donor ability was not obtained (chlorpromazine > promazine = levomepromazine > triflupromazine). The Km-values, characterizing the reaction between NADH and the different enzyme-drug complexes, were estimated. The data suggest that the enzyme-chlorpromazine complex has the best affinity for NADH. The stimulatory effect of levomepromazine closely followed that of promazine.

Animals↗
PubMed1989

Fluorescence studies on binding of amphiphilic drugs to isolated lamellar bodies: relevance to phospholipidosis.

Lysosomal phospholipid storage disorder in lung tissue was observed during chronic treatment with amphiphilic amine drugs. The prevailing and widely accepted mechanism of phospholipidosis is that amphiphilic drugs bind to phospholipids and make the phospholipids unsuitable substrates for the action of phospholipases. We investigated hydrophobic and hydrophilic binding of fifteen drugs to the phospholipid storage organelle, lung lamellar bodies, isolated from male Sprague-Dawley rats. Hydrophobic interactions were studied using 1,6-diphenyl-1,3,5-hexatriene as a fluorescent probe and hydrophilic binding was studied using 1-anilino-8-naphthalene sulfonate as a fluorescent probe. The binding parameters were calculated using Scatchard equations. Of the fifteen drugs used, nine drugs bound to the hydrophobic moiety of lamellar bodies. The order of binding capacities was promethazine greater than chloramphenicol greater than amiodarone = desethylamiodarone greater than promazine greater than chlorpromazine greater than trimipramine greater than propranolol greater than imipramine much greater than chlorphentermine, phentermine, chloroquine, chlorimipramine, cyclizine and chlorcyclizine. Two binding affinities were calculated for all the bound drugs. Binding affinities to hydrophilic sites of lamellar bodies were calculated in terms of emission coefficients for 1-anilino-8-naphthalene sulfonate in the presence of drugs. Hydrophilic binding was in the order chlorpromazine greater than chlorimipramine greater than promazine greater than trimipramine greater than imipramine greater than chlorcyclizine greater than propranolol greater than promethazine greater than chlorphentermine greater than cyclizine greater than phentermine greater than chloroquine much greater than chloramphenicol, amiodarone and desethylamiodarone. The binding affinities of chlorinated analogs were stronger to hydrophilic sites when compared to the parent compound. Amiodarone, which is known to induce pulmonary phospholipidosis and its major non-polar metabolite, desethylamiodarone, bound strongly to lamellar bodies. These two drugs also inhibit phospholipases in vitro. The drugs with weak phospholipidosis-inducing capacity and extensive in vivo metabolism, namely, imipramine, chlorpromazine and promazine, also bound strongly to lamellar bodies with hydrophilic as well as hydrophobic interactions. On the other hand, chloroquine, which is known to induce phospholipidosis and to inhibit phospholipases, did not bind to lamellar bodies. Two major conclusions could be drawn from this study: one is that the drug interactions with isolated lamellar bodies could be studied using membrane fluorescence probes, 1,6-diphenyl-1,3,5-hexatriene and 1-anilino-8-naphthalene sulfonate; second is that the amphiphilic drugs bind to lamellar bodies, as reported for phospholipid vesicles, and the binding of drugs to lamellar bodies could be correlated with their phospholipidosis-inducing capacity only if

Amines↗