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PubMed1995

Blockers for excitatory effects of achatin-I, a tetrapeptide having a D-phenylalanine residue, on a snail neurone.

Some histamine H1 receptor antagonists suppressed the inward current (Iin) of an Achatina identifiable neurone type, PON (periodically oscillating neurone), caused by an Achatina endogenous tetrapeptide having a D-phenylalanine residue, achatin-I (Gly-D-Phe-Ala-Asp), under voltage clamp. Achatin-I was applied locally to the neurone by brief pneumatic pressure ejection and antagonists were administered by perfusion. The dose-response curves of the effective histamine H1 antagonists indicated their potency order to suppress the Iin as follows: chlorcyclizine, promethazine, triprolidine and homochlorcyclizine > trimeprazine and clemastine > diphenylpyraline. The potent drugs were mostly piperazine and phenothiazine types. The effects of chlorcyclizine, promethazine and triprolidine on the dose (the duration of the pressure ejection)-response curve of achatin-I indicated that these drugs affected the Iin caused by achatin-I in a non-competitive manner. The antagonists for the receptors of the small-molecule neurotransmitters other than histamine H1, such as histamine H2, acetylcholine, gamma-aminobutyric acid (GABA), L-glutamic acid, dopamine, alpha- and beta-adrenalin and 5-hydroxytryptamine, had no effect on the Iin caused by achatin-I.

Amino Acid Sequence↗
PubMed1975

Simultaneous detection of a wide variety of commonly abused drugs in a urine screening program using thin-layer identification techniques.

A single-step extraction method and thin-layer identification techniques capable of testing a wide variety of drugs of abuse are presented. These techniques are well suited for large and/or small drug programs involved in urine testing because they provide substantial economic benefits and improve clinical functioning. The drugs are absorbed on a 6 X 6 cm piece of paper loaded with cation-exchange resin and then eluted from the paper at pH 10.1 using ammonium chloride-ammonia buffer. The simultaneous thin-layer detection of sedatives, hypnotics, narcotic analgesics, central nervous system stimulants and miscellaneous drugs is accomplished by spotting the solution of extracted residue on a 20 X 20 cm Gelman pre-coated silica gel glass microfiber sheet (ITLC Type SA). A two-stage solvent system is used in order to obtain a chromatogram with optimum separation of a wide range of drugs. This system can separate methadone and/or cocaine from propoxyphene, methaqualone, methylphenidate, pentazocine, pipradrol, Doxepin, chlorpromazine, phenazocine, naloxone, naltrexone, imipramine and trimeprazine; amphetamine from phenylpropanolamine and dimethyltryptamine; codeine from dextromethorphan; methamphetamine from dimethyltryptamine, etc. Different detection reagents are then applied in succession to different marked areas of the developed chromatogram. This elegant method of extraction and spraying has enabled us to detect morphine base at a sensitivity level of 0.15 mug/ml, amphetamine sulfate at 1.0 mug/ml, methamphetamine hydrochloride at 0.5 mug/ml, phenmetrazine hydrochloride at 0.5 mug/ml, codeine phosphate at 0.5 mug/ml, methadone hydrochloride at 1.0 mug/ml, secobarbital at 0.36 mug/ml and phenobarbital at 0.5 mug/ml in urine. The minimum volume of urine needed to achieve these sensitivities is 20 ml. The cost of analysis per urine specimen using these techniques for concomitant screening of these drugs is less than US$ 1.

1-Propanol↗
PubMed1984

Susceptibilities of drugs to nitrosation under standardized chemical conditions.

Of 22 drugs with either a N,N-dimethylamino, N,N-diethylamino or N-morpholino group in the molecule, eight were converted to volatile N-nitrosamines by nitrosative cleavage in reactions of nitrite and drug in a molar ratio of 4:1 at pH 3. Under standardized conditions yields were greatest with aminopyrine and minocycline which contains two N,N-dimethylamino groups in the molecule. Oxytetracycline, chlortetracycline, tetracycline, promethazine, chlorpromazine, imipramine and disulfiram gave much lower yields and amitriptyline, clomiphene, clomipramine, dextropropoxyphene, diphenhydramine, disopyramide, erythromycin, mepyramine, methapyrilene, penicillin G procaine salt, procaine, tamoxifen, trimeprazine and tripelennamine yielded no detectable levels of volatile N-nitrosamines. Nitrosation products of 57 drugs were also examined by a group selective procedure estimating both volatile and non-volatile N-nitroso compounds. Virtually all of the yield obtained from aminopyrine or minocycline could be accounted for by N-nitrosodimethylamine (NDMA). However, compounds yielding excess N-nitrosamines compared to NDMA were obtained from the other three tetracyclines, presumably as a result of the cleavage of a methyl group from the N,N-dimethylamino substituent to form desmethyl-N-nitroso compounds. In general, the drugs giving the highest yields of N-nitroso compounds were those containing secondary rather than tertiary amino groups. A considerable range of susceptibilities towards nitrous acid was observed overall; ten drugs containing a secondary or tertiary amino- or amido- or hydrazido - group did not react with nitrous acid to form N-nitroso compounds.

Chemical Phenomena↗
PubMed1994

Anaesthesia for burns in children: a review of procedures practised at Red Cross War Memorial Children's Hospital, Cape Town.

Burns anaesthesia for children is a potentially hazardous procedure. We describe our technique developed over a number of years which allows a relatively large number of patients to be dealt with safety in limited theatre time. The technique involves an oral premedication with atropine (0.02 mg/kg), trimeprazine (3 mg/kg) and droperidol (0.2 mg/kg). Intramuscular ketamine (10 mg/kg) is used after an initial halothane induction and anaesthesia is maintained with intravenous ketamine, and a nitrous oxide/oxygen mixture given via nasal prongs. The advantages of the technique together with precautions and monitoring employed are discussed.

Anesthesia, General↗
PubMed2000

Post-column oxidative derivatization for the liquid chromatographic determination of phenothiazines.

A first post-column chemical derivatization method for the liquid chromatographic determination of phenothiazines is presented. Peroxyacetic acid is introduced as a derivatizing agent for phenothiazines, yielding the colored radical cations or fluorescent sulfoxides, depending on reaction conditions. Both reaction products were successfully employed for the detection of the phenothiazines after their liquid chromatographic separation. The fluorescence spectroscopic detection of the sulfoxides proved to be the more robust and sensitive method. Limits of detection ranged from 4 nM for triflupromazine and trimeprazine to 300 nM for phenothiazine for the fluorescence spectroscopic detection of the sulfoxide and from 0.3 microM for phenothiazine and triflupromazine to 2 microM for trifluperazine for the UV-Vis spectroscopic detection of the radical cation. The calibration functions for the fluorimetric sulfoxide determination ranged from two to more than three decades, starting at the limit of quantification.

Chromatography, High Pressure Liquid↗
PubMed2002

Enantioseparation of phenothiazines in cyclodextrin-modified micellar electrokinetic chromatography.

In this study, enantioseparations of five phenothiazines in cyclodextrin (CD)-modified micellar electrokinetic chromatography (MEKC) were investigated using a citrate buffer containing tetradecyltrimethylammonium bromide (TTAB) as a cationic surfactant at low pH. Beta-cyclodextrin (beta-CD) and hydroxylpropyl-beta-CD (HP-beta-CD) were selected as chiral selectors. The results indicate that the separation window is greatly enlarged by beta-CD concentration and that the separability and selectivity of phenothiazines are remarkably influenced by the concentrations of both beta-CD and TTAB, as well as buffer pH. The interaction of thioridazine with beta-CDs is considerably reduced in the presence of TTAB micelles due to competitive complexation of thioridazine with TTAB micelles, which is pH-dependent. As a result, effective enantioseparation of thioridazine is simultaneously achievable with that of trimeprazine and promethazine or ethopropazine in MEKC with addition of either beta-CD or HP-beta-CD, respectively, to a micellar citrate buffer containing TTAB at pH 3.5. Better enantioresolution of thioridazine in MEKC than in capillary zone electrophoresis can be obtained.

Chromatography, Micellar Electrokinetic Capillary↗
PubMed1999

Ultraviolet B (UVB) light-induced histamine release from rat peritoneal mast cells and its augmentation by certain phenothiazine compounds.

When rat peritoneal mast cells were exposed to ultraviolet (UV) light (UVA, UVB and UVC), histamine release was evoked in a dose (intensity X time) dependent manner. The potency order of UV light in inducing the histamine release was UVC > UVB >> UVA. In this study, we focused on the effect of ultraviolet B (UVB) on histamine release from rat mast cells. The UVB-induced histamine release occurred at doses higher than 7.8 kJ m(-2), even at 4 degrees C. At a UVB dose of 18.8 kJ m(-2), where a 51.9+/-4.8% histamine release and a 58.8+/-6.8% degranulation took place, Trypan blue-stained cells accounted for 14.4+/-1.3% of the cells, and the lactate dehydrogenase (LDH) release was about 4.9+/-2.8%. This suggests that the membrane permeability to low molecular weight substances was increased by UVB exposure. The UVB-induced histamine release was inhibited by ascorbic acid at concentrations higher than 500 microM, suggesting the involvement of a radical reaction in the process. The UVB-induced histamine release was enhanced by some phenothiazine compounds, i.e., promethazine, trimeprazine, mequitazine, chlorpromazine, trifluoperazine, ethopropazine and thioridazine. We conclude that the phototoxicity of phenothiazine compounds may be due in part to an enhancement of UVB-induced histamine release from mast cells.

Adjuvants, Immunologic↗
PubMed2003

Inactivation of cholinesterase induced by chlorpromazine cation radicals.

To clarify the mechanism of the side effect of chlorpromazine, we examined the inactivation of cholinesterase induced by chlorpromazine. Cholinesterase was inactivated and its activity was lost in rat serum during interaction of chlorpromazine with horseradish peroxidase and H2O2. When chlorpromazine was oxidized by horseradish peroxidase and H2O2, the reaction solution colored pink and the visible absorption spectrum was consistent with the absorption spectrum of the chlorpromazine cation radical (CPZ*+). Adding cholinesterase immediately decreased the pink color of CPZ*+, indicating that CPZ*+ directly attacked cholinesterase to cause loss of the enzyme activity. Tryptophan residues in cholinesterase sharply decreased during the interaction of cholinesterase with horseradish peroxidase and H2O2. Presumably, loss of tryptophan residues changed the conformation of the cholinesterase protein and then the activity of the enzyme was lost. Other phenothiazine derivatives, including promethazine, triflupromazine, trifluoperazine, trimeprazine, thioridazine and perphenazine, also inactivated cholinesterase during the oxidation by horseradish peroxidase and H2O2. These results suggest that phenothiazine cation radicals participate in toxicological signs caused by the drugs.

Animals↗
PubMed1999

Spontaneous reporting of suspected adverse reactions to antihistamines: a national and international perspective.

Twenty-one sedative and five non-sedating antihistamines are presently available on the UK market. Analysis of spontaneous reports of suspected adverse drug reactions was performed for those drugs with more than 90 reported reactions on the UK ADROIT database to the period ending 31 December 1997. Thus nine antihistamines, (four sedative antihistamines and five non-sedating antihistamines) were included. For each of the four sedative agents (azatidine, chlorpheniramine, diphenhydramine and trimeprazine), reactions associated with the cardiovascular, gastrointestinal, central nervous systems, the skin, general and psychiatric reactions made up more than 70% of total reported reactions. For all four agents, fatal reactions constituted less than 2.5% of total reactions. For each of the five non-sedating agents (acrivastine, astemizole, cetirizine, loratidine and terfenadine), reactions associated with the cardiovascular, gastrointestinal central nervous systems, the skin, general and psychiatric disorders together made up more than 75% of total reported reactions. For all five non-sedating agents, fatal reactions constituted less than 1% of total reactions. However, there were 21 reports of fatality in association with terfenadine, 11 (52%) of which were either sudden deaths or those associated with a cardiac rate of rhythm reaction. Analysis of the WHO database for non-sedating drugs showed a similar pattern, with terfenadine being associated with the highest frequency of reports of potentially serious arrhythmias and of sudden death and death related to disturbances of cardiac rate and rhythm combined. Despite the limitations of spontaneous reporting systems, comparison of the benefit-risk profiles of drugs using this data within a class of drugs can provide valuable information, and pharmacovigilance of antihistamines (and all other agents) using this and other means should continue for the lifetime of their use in humans.

Adverse Drug Reaction Reporting Systems↗
PubMed2000

Human term placental lipoxygenase-mediated N-demethylation of phenothiazines and insecticides in the presence of linoleic acid.

This study investigated the hypothesis that human term placental lipoxygenase (HTPLO) and soybean lipoxygenase (SLO) are capable of mediating N-demethylation of selected phenothiazines and insecticides in the presence of linoleic acid (LA). In addition to being LA dependent, the N-demethylation reaction mediated by HTPLO and SLO was limited by incubation time, pH of the medium, concentration of the enzyme and the substrate. Using Nash reagent to monitor formaldehyde production, the specific activity for LA-dependent N-demethylation of chlorpromazine, a model phenothiazine, was determined to be 1.7+/-0.3 nmoles/min/mg HTPLO. Besides chlorpromazine, N-demethylation of promazine, promethazine and trimeprazine was also observed. The insecticide, aminocarb, displayed a specific activity of 2.2+/-0.3 nmoles/min/mg HTPLO for N-demethylation. Other insecticides, namely chlordimeform, dicrotophos and zectran, were oxidized in a similar manner. As compared with HTPLO, the rates of N-demethylation of phenothiazines and insecticides mediated by SLO were higher. Classical inhibitors of lipoxygenase, as well as antioxidants and free radical scavengers, caused a dose-dependent reduction in the production of formaldehyde from chlorpromazine and aminocarb by HTPLO. These results clearly demonstrate the ability of polyunsaturated free fatty acids to support N-demethylation of xenobiotics via the lipoxygenase pathway.

Carbamates↗
PubMed2005

Mucosal delivery of cytotoxic therapeutic agents: response of rat nasal mucosa to microencapsulated ethopropazine HCl enantiomer.

Use of microencapsulation technology in combination with absorption enhancers eliminated epithelium irritation and necrosis commonly associated with nasal delivery of cytotoxic therapeutic agents. Phenothiazines, such as ethopropazine (ETZ), promethazine, trimeprazine and propiomazine have been used for the treatment of allergenic conditions, motion sickness, nausea, Parkinson's disease, Prion disease and as a sedative for psychiatric disorders. The enantiomers of commercially available racemic phenothiazines were isolated and purified using classical diastereomeric salt techniques. The racemate and the enantiomers of ETZ were tested in vitro for their cellular toxicity using lung fibroblast cells. Each enantiomer was shown to be cytotoxic at concentrations greater than 10(-5) molar. The ETZ enantiomers were encapsulated using spinning disk atomization to prepare a nasal delivery dosage form that does not produce an irritation response. Release rates for the ETZ microcapsules were determined in vitro and an animal study was conducted to determine the irritation response of rat nasal mucosa when dosed with encapsulated vs. non-encapsulated ETZ.

Animals↗
PubMed1995

Inhibition of radiation-induced changes of glyoxalase I activity in mouse spleen and liver by phenothiazines.

Swiss albino mice (male) were irradiated with gamma-rays at a dose-rate of 0.05 Gy s-1, and the activities of glyoxalase I (GI) and glyoxalase II (GII) were determined after 24 h in the spleen and liver. Radiation up to 4 Gy increased the activity of GI and decreased that of GII. It was possible that the radiation-induced changes in the activity of the glyoxalase system, particularly that of GI, were suggestive of the regeneration status of the tissue. Phenothiazines such as chlorpromazine (CPZ), promethazine (PMZ) and trimeprazine (TMZ) inhibited the radiation-enhanced activity of GI in a concentration-dependent manner. On the other hand, almost no change in the activity of GII was observed using phenothiazines. The effect of phenothiazines on radiation-induced changes of glyoxalase activity were reversed in the presence of ferrous (Fe2+) ions. However, phenothiazines inhibited the radiation effect in the presence of ferric (Fe3+) ions. This combined effect was predominant in the liver. A possible mechanism for the modifying effect of phenothiazines is suggested.

Animals↗
PubMed2001

Trypanosoma cruzi trypanothione reductase is inactivated by peroxidase-generated phenothiazine cationic radicals.

Trypanosoma cruzi trypanothione reductase (TR) was irreversibly inhibited by peroxidase/H2O2 /phenothiazine (PTZ) systems. TR inactivation depended on (a) time of incubation with the phenothiazine system; (b) the peroxidase nature and (c) the PTZ structure and concentration. With the most effective systems, TR inactivation kinetics were biphasic, with a relatively fast initial phase during which about 75% of the enzyme activity was lost, followed by a slower phase leading to total enzyme inactivation. GSH prevented TR inactivation by the peroxidase/H2O2/PTZ+* systems. Production of PTZ+* cation radicals by PTZ peroxidation was essential for TR inactivation. Horseradish peroxidase, leukocyte myeloperoxidase (MPO) and the pseudo-peroxidase myoglobin (Mb) were effective catalysts of PTZ+* production. Promazine, thioridazine, chlorpromazine, propionylpromazine prochlorperazine, perphenazine and trimeprazine were effective constituents of the HRP/H2O2 /PTZ system. The presence of substituents at the PTZ nucleus position 2 exerted significant influence on PTZ activity, as shown by the different effects of 2-trifluoromethyl and 2-H or 2-chlorophenothiazines. The PTZ+* cation radicals disproportionation regenerated the non-radical PTZ molecule and produced the PTZ sulfoxide that was inactive on TR. Thiol compounds including GSH interacted with PTZ+* cation radicals transferring an electron from the sulfide anion to the PTZ+*, thus nullifying the PTZ+* biological and chemical activities.

Animals↗
PubMed1987

Effects of fasting and oral premedication on the pH and volume of gastric aspirate in children.

The pH and volume of gastric aspirate were measured immediately after the induction of anaesthesia in 224 healthy children to determine the effects of decreasing the period of fasting and of giving oral premedicants before anaesthesia. Fasting for less than 4 h was found to increase the volume of gastric aspirate and the risk of developing pulmonary aspiration syndrome. Trimeprazine syrup was found to increase the pH of the gastric contents, and decrease the likelihood of the pulmonary aspiration syndrome. There was a significant increase in gastric volume in patients premedicated with temazepam elixir which did not occur in patients given temazepam capsules. These results support the custom of fasting patients for at least 4 h before anaesthesia and indicate that oral premedicants and their vehicles can have significant effects on the stomach.

Administration, Oral↗
PubMed1997

Comparison of suxamethonium and different combinations of rocuronium and mivacurium for rapid tracheal intubation in children.

The use of suxamethonium in children is associated with undesirable side effects. The synergistic effect of a rocuronium-mivacurium combination can be considered as an acceptable alternative to suxamethonium in clinical practice. The calculated ED50 of the rocuronium-mivacurium mixture was only 62% of the predicted value assuming a purely additive interaction. The use of this combination has not been evaluated in children. In this two-part study, we assessed the intubating conditions and pharmacodynamics of suxamethonium, rocuronium, mivacurium or a rocuronium-mivacurium combinations in children. We studied 120 ASA I children of both sexes, aged 3-10 yr. Children were premedicated with trimeprazine 2 mg kg-1 orally, and received fentanyl 2 micrograms kg-1 and propofol 2 mg kg-1 for induction of anaesthesia. They were allocated randomly to receive one of the following drugs or drug combinations: suxamethonium 1.0 mg kg-1, mivacurium 0.2 mg kg-1, rocuronium 0.6 or 0.9 mg kg-1, mivacurium 0.1 mg kg-1 with rocuronium 0.3 mg kg-1 or mivacurium 0.15 mg kg-1 with rocuronium 0.45 mg kg-1. In part 1, 60 s after administration of the neuromuscular blocking drug or drug combination, tracheal intubation was performed in 60 children by mimicking rapid sequence induction, and intubating conditions were evaluated by a blinded investigator according to a standard score. In part 2, neuromuscular monitoring was established before administration of neuromuscular blocking agent(s) and the time from injection of drug or drug combination until complete ablation of T1 (onset) and recovery of T1 to 25% (duration) were recorded in another 60 children. The frequency of distribution of excellent or good intubating conditions in the higher dose of rocuronium and the combination groups were similar to those in the suxamethonium group, but significantly different (P < 0.05) from those in the mivacurium group. Mean onset time was faster in the suxamethonium (55.1 (SD 11.4) s), rocuronium 0.9 mg kg-1 (70.5 (37.7) s), mivacurium 0.1 mg kg-1 with rocuronium 0.3 mg kg-1 (67 (35.9) s) and mivacurium 0.15 mg kg-1 with rocuronium 0.45 mg kg-1 (55 (26.7) s) groups compared with the mivacurium 0.2 mg kg-1 (116 (26.8) s) and rocuronium 0.6 mg kg-1 (97.9 (29) s) groups. This study demonstrated that the combination of rocuronium 0.45 mg kg-1 and mivacurium 0.15 mg kg-1 could possibly be considered as an acceptable alternative to suxamethonium when rapid sequence induction of anaesthesia is indicated in children because it provides uniform excellent intubating conditions and complete neuromuscular block in < 60 s.

Androstanols↗
PubMedDate not supplied

Study of the metabolism of phenothiazines: determination of N-demethylated phenothiazines in urine.

When phenothiazine drugs (chlorpromazine, promazine, promethazine, propiomazine, propionylpromazine, trifluoperazine and trimeprazine) were reacted with m-chloroperbenzoic acid, N-demethylated phenothiazines were obtained in moderate yield. The mass spectra of the N-demethylated phenothiazines showed either m/z 44 and 72 or m/z 58 as characteristic ions depending on their side chain. The N-demethylated propiomazine was identified as a metabolite of propiomazine from the urine of a rat which was given propiomazine orally.

Animals↗
PubMed1986

Clinical pharmacological evaluation of an assay kit for intoxications with tricyclic antidepressants.

The performance of an enzyme immunoassay kit (EMIT) to diagnose intoxications with tricyclic antidepressants was compared with a high performance liquid chromatography (HPLC) technique in vitro and in vivo. The cut-off reference solution contained in the kit of nominally 1,140 nM nortriptyline varied from 1,250 to 1,600 nM. In vitro addition of antidepressants gave positive results (change in absorbance above the cut-off value) of approximately 1,100 nM for amitriptyline, imipramine, and desmethylimipramine and approximately 1,600 nM for clomipramine and desmethylclomipramine. In contrast, high concentrations of the tetracyclic antidepressant maprotiline (7,000 nM) and the bicyclic zimeldine (2,000 nM) gave negative results. False positive results were obtained with high concentrations of thioridazine (4,000 nM), chlorpromazine (300 nM), and alimemazine (trimeprazine) (5,000 nM). Of 51 patient samples, five gave readings above the cut-off value, consistent with a tricyclic antidepressant intoxication, but two of these were false positives as compared with the specific HPLC analysis. However, no false negative results were obtained with the EMIT. In conclusion, the EMIT kit is likely to detect intoxications with tricyclic antidepressants but miss intoxications with nontricyclic antidepressants. For a screening method, this is a serious drawback, since maprotiline and zimeldine together make up approximately 25% of the total of antidepressants used in Sweden. Users of the kit must also be aware that certain phenothiazines in high therapeutic doses or in intoxication cases could interfere with this test and might lead to the false diagnosis of intoxication with tricyclic antidepressants.

Antidepressive Agents, Tricyclic↗