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The in vitro plasma protein binding of phenytoin (diphenylhydantoin), salicylic acid, propranolol, pethidine (meperidine) and chlorpromazine was measured using an air-driven, bench-top ultracentrifuge and the results were compared with those obtained by equilibrium dialysis. For all drugs studied, except chlorpromazine, a significant correlation was found between the plasma binding results obtained by the two methods. However, only in the case of propranolol the actual binding values obtained by the two techniques were very similar. In the case of phenytoin, salicylic acid and pethidine, ultracentrifugation gave higher plasma binding values than equilibrium dialysis. Binding values obtained by the two methods for chlorpromazine were not correlated at all. This may be explained by binding of chlorpromazine to the very low density lipoprotein fraction which floats after ultracentrifugation. The described ultracentrifugation binding technique may be useful to rapidly measure the plasma binding of certain drugs in microsamples.

The mass fragmentography and the gas-liquid chromatography are available actually for quantitation of very low levels of neuroleptics. The Radio-immunological assay is full of promise. Their plasma levels are not correlated with their dosage in a man to another, but, for some of them, there is lineary relation for one person. A correlation between their levels and their clinical efficacy is not certainly demonstrated for thioridazine and non transformed chlorpromazine; it could be possible for his sulphoxide metabolite and for butaperazine. The sides-effects are relatively correlated with their levels in the begining of the therepautic. The antiparkinsonian drugs, the antidepressants and the lithium could influenced them.

A rapid and reliable procedure, based on a C8 bonded phase extraction and reversed-phase isocratic high-performance liquid chromatographic separation with internal standard quantitation, has been developed for the determination of the antipsychotic drug chlorpromazine and thirteen common metabolites. The method allows quantitation of these analytes at the ng/ml concentration range in human plasma. An evaluation of recovery, detection limits, and reproducibility is presented along with application of the method to patient samples.

A method for the assay of 7-hydroxychlorpromazine in biological fluids is described. The stages of the method are extraction into ether, back extraction into acid, alkalinisation and further extraction into ether, evaporation of the extract to dryness, and gas-chromatography of the extracted material as a silylated derivative using conditions previously described for chlorpromazine. The method is applicable to certain other hydroxylated chlorpromazines, but it is not superior to existing methods for the assay of nonhydroxylated analogues. Only small quantities of 7-hydroxychlorpromazine were detected in the plasma of schizophrenics showing a satisfactory clinical response, even when the compound was present in urine, providing strong evidence that the presence of 7-hydroxychlorpromazine in blood is not a pre-requisite of successful therapy.

Plasma levels of chlorpromazine (CPZ) and prolactin were measured repeatedly in 14 psychiatric patients throughout CPZ treatment. Mean prolactin level was elevated in 11 subjects (all six women and five of eight men). Mean plasma prolactin correlated significantly with mean plasma CPZ but not with the dose of the drug. Only patients with mean plasma prolactin above 35 ng/ml developed Parkinsonian side-effects.

We describe a gas-chromatographic method for measuring chlorpromazine and its metabolites chlorpromazine sulfoxide, mono-N-desmethylchlorpromazine, and di-N-desmethylchlorpromazine at therapeutic concentrations in human serum, with use of a nitrogen detector. The compounds are extracted from serum at pH 10.5 into hexane/isoamyl alcohol, re-extracted into dilute HCl, and then extracted into hexane after alkalinization of the HCl. The N-desmethylated metabolites are measured as their respective N-trifuloracetyl derivatives; the parent drug and its sulfoxide are measured as the unchanged bases. Promazine is the internal standard. As little as 5 micrograms of chlorpromazine, 20 micrograms of chlorpromazine sulfoxide, 20 micrograms of mono-N-desmethylchlorpromazine, and 10 micrograms of di-N-desmethylchlorpromazine per liter can be measured in 2-mL samples of serum. The within-run coefficients of variation for assays of these drugs at 100 micrograms/L are 2.7%, 5.6%, 5.1%, and 5.3%, respectively. The procedure was applied to patients receiving therapeutic doses of chlorpromazine and to patients who had ingested an overdose of chlorpromazine.

In peripheral tissues of male rats given 25 mg of didesmethylchlorpromazine [gamma-(2-chlorophenothiazinyl-10)-propylamine, Cl-PPA] per kg ip, high levels of the corresponding sulfoxide (Cl-PPA-SO) and the sulfone (Cl-PPA-SO2) were measured during the following 2-24 hr. Small quantities of these metabolites were excreted in bile, whereas 7-hydroxy-Cl-PPA could not be detected. By comparison of the areas under the tissue concentration-time curves with those measured after injection of Cl-PPA-SO2, it could be shown that at least 50% of the Cl-PPA dose was converted to the sulfone. Following administration of Cl-PPA-SO, the sulfone was present in tissues and in urine. An NADPH-dependent oxygenase catalyzing the conversion of Cl-PPA-SO to Cl-PPA-SO2 was localized in liver microsomes. Attempts to characterize the enzyme by means of induction and inhbition experiments did not lead to unequivocal conclusions concerning its nature.

High-performance thin-layer chromatography was used to determine chlorpromazine, amitriptyline, nortriptyline, imipramine, desipramine, phenobarbital, and phenytoin in plasma, to demonstrate the utility of this technique for routine analysis. We quantitated the separated components by use of ultraviolet reflectance spectrometry with detection limits as low as 1 microgram/liter. Regressions of psychoactive agents extracted from plasma were linear over the range of 0 to 300 microgram/liter. The anti-convulsant drugs, phenobarbital and phenytoin, were determined over a range of 0 to 50 mg/liter. Analyses were rapid, reproducible, and well-suited to large-scale programs. Separated components also can be identified in situ by ultraviolet spectrophotometry.

Platelet activating factor (PAF; 1-alkyl-2-acetyl-sn-glycero-3-phosphocholine) is a potent bioactive phospholipid released from platelets, neutrophils, basophils and macrophages that has been proposed as a mediator of anaphylaxis, acute lung injury and other disorders. Specific factors which stabilize PAF and/or regulate PAF activity in body fluids are largely unknown. As part of a general autacoid-serum protein binding screen, the platelet activating factor-alpha-1-acid glycoprotein (PAF-AAG) interaction was indirectly characterized by examining the ability of PAF to displace propranolol from AAG. Both PAF and its deacetylated metabolite (lyso-PAF), at 20 microM, doubled the fraction unbound of propranolol (0.4 microM) from purified human AAG (20 microM). None of the other autacoids that were studied (epinephrine, serotonin, spermidine, putrescine, leu-enkephalin or phenethylamine) exhibited any propranolol displacement activity. Scatchard analysis indicated that PAF competitively displaced propranolol from AAG, causing the apparent affinity constant for propranolol-AAG to decrease from 1.8 X 10(5) M to 6.9 X 10(4) M. PAF behaved qualitatively like chlorpromazine (a documented inhibitor of propranolol binding to AAG), but PAF was less effective at displacing propranolol. The apparent binding to AAG may help stabilize and transport extracellular PAF. Furthermore, the interaction of PAF and AAG suggests that serum AAG, which fluctuates in a number of diseases, may function to regulate PAF activity during acute and chronic disease states.

Chlorpromazine (CPZ) therapeutic drug monitoring is beset by inconclusive and controversial evidence on the positive correlation of plasma CPZ concentration and psychiatric improvement. Failure to establish meaningful correlation between plasma concentration and clinical benefit may be explained by chemical assay problems; differences in the pharmacokinetic plasma CPZ and metabolite profile due to age, acuteness or chronicity of the disease; drug interactions; and duration of neuroleptic treatment. At the other end, measurement of clinical effects in psychiatry suffers such drawbacks as less distinct and specific clinical end points, the patient's subjectiveness of symptoms and the investigator's subjectiveness on clinical scoring, and the ethical consideration of placebo use. Our data showed the following:L (1) Plasma levels of CPZ parent compound correlated better with improvement in thought disorders and paranoid delusion than with total Brief Psychiatric Rating Scale; there were no correlations with depression and withdrawal retardation. (2) Chronically treated patients achieved significantly lower plasma CPZ compared to acutely treated patients on oral CPZ dose but not those treated with an intramuscular dose. (3) Children, in comparison to adults, require higher doses to achieve similar plasma CPZ levels and have a lower response threshold, both for clinical improvement and toxicity. (4) The plasma concentration of CPZ can be diminished by concomitant use of anticholinergics. (5) A drug "holiday" increases peak plasma concentration of CPZ and may benefit the nonresponders.

A dose of 50 mg of chlorpromazine (CPZ) was given to 6 untreated schizophrenic patients and 8 healthy volunteers at 7:00 a.m. before breakfast. Blood samples were taken 3, 6, 9 and 24 hrs after for the analyses of CPZ and its metabolites by gas chromatographic techniques. In the cases of schizophrenic patients, the CPZ treatment was continued. Serum drug levels were monitored and clinical response assessed. The drug levels in serum of another group of patients already under long term treatment were also determined. Although wide inter-patients variations in serum drug levels after a single dose administration were observed, the CPZ level in the patients decreased faster than in the normal subjects. Patients showing high levels of the metabolites such as demethylated CPZ and CPZ sulfoxide after a single dose of CPZ tended to achieve poorer clinical improvement in CPZ therapy, agreeing with the results that poor responders to long term CPZ treatment revealed relatively high levels of the metabolites of CPZ compared with CPZ level. The results indicate that the study of a single dose administration prior to initiating treatment with CPZ can be used to determine how an individual patient would respond to CPZ therapy and be a valuable tool in the rational pharmacotherapy of schizophrenic patients.

Plasma chlorpromazine (CPZ) levels were studied in children 8 to 15 yr of age who were receiving CPZ for mental disorders. The results showed that children need larger doses of CPZ than adults to attain comparable plasma concentrations. The apparent therapeutic plasma concentration in children (40 to 80 ng/ml) is lower than that reported for adults (50 to 300 ng/ml). In the children studied, the plasma concentrations declined despite maintained dosage, possibly because of autoinduction of CPZ metabolism. Doses of 6 to all mg/kg body weight, and even as much as 850 mg/day, were tolerated without significant side effects when administered in divided doses 3 or 4 times a day, while doses of less than 6 mg/kg/day frequently failed to produce the desired plasma CPZ levels.

The binding to human intact erythrocytes of two different spin-labelled derivatives of chlorpromazine has been studied. The influence of the positively charged side chain of the drug has been the focus of our attention. The positively charged amphiphilic compound (spin derivative I) is water-soluble up to 80 microM at pH values below 5.9. The apolar analogue (spin derivative II) aggregates in aqueous buffer from the lowest concentration tested. Both spin derivatives undergo a slow reduction inside the erythrocyte. The reduced nitroxides are readily reoxidized by adding a low, non-quenching, concentration of potassium ferricyanide to the intact erythrocytes. The fractions of spin label I and II bound to the erythrocyte membrane or to the erythrocyte-extracted lipids remain constant as a function of the temperature (3-42 degrees C) and as a function of the concentration of the spin label up to 150 microM. E.s.r. spectra of both spin labels show a two-component lineshape when they are bound to intact erythrocytes. Below 35 degrees C for the positively charged spin probe, and below 32 degrees C for the apolar spin probe, the simulation of the lineshape shows that more than 50% of the spectrum originates from a slow-motion component. This slow-motion component is also found in erythrocyte-extracted lipids probed by the positively charged spin label below 25 degrees C. In contrast, no slow-motion component is detected in the range 4-40 degrees C for the apolar spin label in erythrocyte-extracted lipids. In this environment the apolar probe experiences a single fast anisotropic motion with an exponential dependence on 1/temperature. Detailed lineshape simulations take into account the exchange frequency between binding sites where the probe experiences a fast motion and binding sites where it experiences a slow motion. The exchange frequency is strongly temperature-dependent. Characterization of the different motions experienced inside the different locations has been achieved and compared for whole erythrocytes and for the extracted lipids. The biochemical nature of the binding sites (membrane protein/acidic phospholipid) giving rise to the slow-motion component is discussed as a function of the polarity of the spin-labelled drug and as a function of the temperature controlling the fluidity of the lipid bulk and influencing the distribution of the drug inside the membrane.

Among the neuroleptics chlorpromazine has been the most extensively studied despite its complex metabolic pathways. Several metabolites, in particular 7-hydroxychlorpromazine, are psychotropically active. Oral phenothiazines are extensively metabolised "first-pass" through the liver. The relationship between clinical response and plasma concentrations of neuroleptics is tenous. The reasons for the lack of correlation include spontaneous remission in some patients, problems with flexible dosage schedules, the type of patient studied, differences in metabolic patterns, induction of metabolism in the liver, interactions with other drugs, and variations in plasma protein binding. Alternative research strategies might be to study metabolically less complex drugs such as haloperidol or to relate clinical response to autonomic, extrapyramidal, EEG, biochemical or endocrine measures.

The effects of colestipol hydrochloride, a hypocholesterolemic bile acid-binding anion-exchange polymer, on the GI absorption of drugs commonly used in humans were studied in the rat. Colestipol hydrochloride was given by gavage in single doses of 71.5 or 214.5 mg/kg, equivalent to 5 or 15 g, respectively, in a 70-kg human; controls received equivalent amounts of microcrystalline cellulose. Single oral doses of labeled drugs were given concurrently with colestipol hydrochloride or microcrystalline cellulose at the human therapeutic dose range on a milligrams per kilogram basis. Subsequent changes in serum drug levels were measured at several time periods, and absorption was evaluated as the total area under the time-concentration curve. Colestipol hydrochloride at either dose did not significantly alter the absorption of 6-14C-nicotinic acid, 7-3H-tetracycline, 35S-chlorpromazine, 12alpha-3H-digoxin, warfarin (alpha-14C-benzyl), or clofibrate (14C-carboxyl). In addition, the effects of 214.5 mg/kg of colestipol hydrochloride were compared with the same dose of cholestyramine with respect to the absorption of 3-14C-hydrochlorothiazide, 2-14C-phenobarbital, and 3H-digitoxin. Cholestyramine reduced absorption of hydrochlorothiazide by 42%, but colestipol hydrochloride had no significant effect. Neither resin altered phenobarbital or digitoxin absorption when compared with the the control, but a significant difference occurred between the two resins with digitoxin; areas under the time-concentration curve [in (dpm/0.1 ml serum) x hr] were: colestipol hydrochloride, 2001; cholestyramine, 16,300; and cellulose, 17, 067. These results indicate that colestipol hydrochloride and cholestyramine can differ in their effects on the absorption of certain drugs from the GI tract of the rat.

Recoveries of acepromazine and chlorpromazine from equine plasma were examined. Recoveries of both drugs from plasma were poor under theoretically optimal conditions for basic drugs. When a wide range of extraction pH was examined, it was found that more complete recoveries of these drugs from plasma were achieved at pH 5-6. Use of [3H] chlorpromazine showed that the rate of migration of the drug from an aqueous to a nonpolar environment was much faster at pH 6.0 than at pH 9.2 from both plasma and buffer solutions. Times required for equilibration with agitation were 15 min at pH 6.0, 1 h at pH 9.2, and 2 h at pH 11.0. With these agitation times and pH values, recoveries were more than 95% complete.

In general, plasma level monitoring and pharmacokinetics are widely studied and have been successfully applied in the field of epileptic therapy. Before similar monitoring can be used with psychiatric drugs the possible problems of obtaining samples from the type of patient who receives this therapy should be considered. Patients who receive chlorpromazine sometimes show plasma levels lower than the recommended range, even though their symptoms are considered controlled. Correct interpretation of plasma level results depends on an understanding of the factors responsible for these low plasma levels.

1. Concentrations of total radioactivity in plasma of rats given intravenous and oral (35)S-chlorpromazine, were similar. Concentrations of unchanged drug, however, were lower after oral doses.2. Chlorpromazine circulated in solution through isolated loops of rat intestine was rapidly absorbed by the tissue. Measurements of glucose transport and histological examination indicated that the tissue was intact. In these in vitro experiments some of the chlorpromazine was converted to products, which together with unchanged drug, were partly retained in the intestinal wall and partly transferred to the serosal side of the tissue. Observations at three concentrations supported the hypothesis that transfer of unchanged drug occurred by passive diffusion.3. Conversion of chlorpromazine to metabolites in the intestine in vivo, would account for the differences in concentrations of chlorpromazine and total radio-activity in plasma after oral doses.