Phenazone as a marker of liver-metabolic function in patients with acute leukemia.

OBJECTIVE: The aim of this work was to study the influence of neoplastic disease, especially acute myeloblastic leukemia (AML), and its chemotherapy on the activity of hepatic microsomal enzymes by using phenazone, as a marker of oxidative drug metabolizing activity. METHODS: The observations were carried out in 21 patients with AML and in 53 healthy volunteers. The influence of disease on phenazone kinetics was studied before chemotherapy and the effect of anticancer drugs administration after the first cycle of chemotherapy. RESULTS: The mean phenazone half-life time was significantly shorter in patients with AML (8.79 (3.01) h) than in control group (11.08 (3.61) h) (p < 0.012). Treatment with anticancer drugs, especially with epirubicine, inhibited phenazone elimination. The mean phenazone half-life time was significantly longer (18.08 (8.80) h) and the mean metabolic clearance rate was significantly smaller (33.92 (15.40) ml/min) after chemotherapy in comparison with the initial value, before treatment (10.22 (2.90) h), (p < 0.01) (50.33 (20.29) ml/min) (p < 0.008). CONCLUSION: Our results lead to the conclusion that phenazone is an important index of hepatic metabolic capacity in patients with acute myeloblastic leukemia. The evaluation of its kinetics allowed to early recognition of the presence and the degree of drug oxidizing modification. Acceleration of phenazone elimination before treatment and its inhibition after chemotherapy, particulary epirubicine, may suggest that in patients with AML elimination of the other drugs metabolized by the pathway similar to phenazone also may be changed. It should be considered in individualization of their dosage regimen.     

Disappearance of phenazone from plasma in patients with obstructive jaundice

Summary The influence of obstructive jaundice on the plasma disappearance of phenazone has been studied. The elimination rate of the drug reflects the ability of the liver to hydroxylate it and possibly other drugs, too. A new analytical method based on gas chromatography was used for the determination of phenazone in plasma. The study was performed in 11 patients with jaundice due to stones in the common bile duct, both during the icteric period and three months later, when the obstruction had been relieved and the plasma bilirubin had returned to normal. A separate group, consisting of five patients with jaundice due to malignant disease, was studied only once. The study failed to show a uniform influence of obstructive jaundice on the elimination rate of phenazone. In two other non-icteric patients the excretion of phenazone in bile was found to be less than 2% of the dose administered.     

The effects of industrial lead poisoning on cytochrome P450 mediated phenazone (antipyrine) hydroxylation

Summary In a group of ten male adults admitted to hospital with clinical symptoms of lead exposure, phenazone elimination rates, blood -amino-laevulinic acid dehydratase (ALA.D) activity, blood lead levels and haemoglobin were measured. Investigations were carried out before, immediately after and again at least 12 weeks after cessation of CaEDTA (sodium calcium edetate) chelation therapy. Following chelation, phenazone elimination rates were increased as assessed by a decrease in half life and increase in clearance. This was significant, both immediately after and 12 weeks after cessation of chelation therapy. The change in rate of phenazone metabolism was associated with improved clinical status, with lowered blood lead levels and raised haemoglobin and ALA.D activity. The results of the study suggest that the depression in phenazone elimination in lead intoxication is possibly due to depressed hepatic cytochrome P450 levels.     

Micha?lis--Menten kinetics of phenazone elimination in the perfused pig liver

The purpose of the present study was to define the elimination kinetics of phenazone (NFN) in the isolated perfused pig liver. In five experiments phenazone was administered as constant infusion to obtain steady-state periods over a wide range of concentrations. The elimination of phenazone followed saturation kinetics (concentrations 0.1-12 mmol x 1(-1) and the maximal elimination rate (Vmax) was on average 102 mumol x min-1 x kg-1 liver and the Micha?lis-constant (Km) of 2.6 mmol x 1(-1). Estimates of Vmax and Km for the microsomal phenazone hydroxylase activity measured in liver biopsies found to be considerably lower than in the perfused liver. The hepatic elimination of phenazone during perfusion of pig liver at phenazone concentrations corresponding to human therapeutic doses follows first-order kinetics.     

Hemmung der Hydroxylierung von Arzneimitteln in vivo unter Äthanolbelastung

Summary In the rat, the pharmacokinetic behaviour of phenazone and aminophenazone (amidopyrine) is changed after administration of ethanol (3.2 ml/kg, p.o.). Urinary excretion studies show a biphasic effect on the elimination of certain metabolites formed by N-demethylation and C-hydroxylation.There is a significant decrease of elimination of these metabolites during the first 5–6 hours after the administration of ethanol. This is followed by a compensatory increase after the ethanol has been metabolized. In contrast, elimination of unchanged phenazone remains unaffected during the first 5 hours after ethanol administration, but is increased later. Correspondingly, the blood level of unchanged phenazone initially shows no difference compared to control but decreases more slowly after ethanol administration. The blood level of the main metabolites of aminophenazone, determined as total aminoantipyrine, is diminished after ethanol and shows considerable delay in reaching its maximum. The observed changes in the pharmacokinetic behaviour of the drugs tested are due to reversible inhibition of microsomal N-demethylation and C-hydroxylation in the liver by ethanol. Such inhibition of microsomal drug metabolism by ethanol may alter the duration and intensity of action of certain drugs when they are given in combination with ethanol.

     

Effect of chronic exposure to carbon disulfide on biotransformation of phenazone in rabbits

A significant but reversible inhibition of phenazone elimination was observed in rabbits chronically exposed to CS₂. Lack of significant difference of phenazone pharmacokinetics in exposed rabbits 24 h after the last exposure compared with the control group, indicates that alteration of phenazone elimination after chronic exposure to CS₂ is reversible. The results obtained with phenazone as a model substance suggest that, during chronic exposure to CS₂, elimination of other drugs metabolized by the pathway similar to phenazone may also be altered. This should be taken into account in selecting their dosage.     

Michaëlis - Menten Kinetics of Phenazone Elimination in the Perfused Pig Liver

Abstract The purpose of the present study was to define the elimination kinetics of phenazone (NFN) in the isolated perfused pig liver. In five experiments phenazone was administered as constant infusion to obtain steady-state periods over a wide range of concentrations. The elimination of phenazone followed saturation kinetics (concentrations 0.1–12 μmol × 1^-1) and the maximal elimination rate (V_max) was on average 102 μmol × min.^-1 × kg^-1 liver and the Michaëlis-constant (K_m) of 2.6 mmol × 1^-1. Estimates of V_max and K_m for the microsomal phenazone hydroxylase activity measured in liver biopsies were found to be considerably lower than in the perfused liver. The hepatic elimination of phenazone during perfusion of pig liver at phenazone concentrations corresponding to human therapeutic doses follows first-order kinetics.     

Two Compartment Analysis of Plasma Elimination of Phenazone in Normals and in Patients with Cirrhosis of the Liver

Abstract The elimination kinetics of phenazone (NFN) after intravenous injection was investigated in seven healthy volunteers and in five patients with chronic liver disease. The plasma concentration/time data of phenazone were analysed according to a one compartment linear model and a two compartment linear open model, respectively. The elimination rate constant, the volume of distribution, and the clearance estimated by the one compartment model analysis correlated significantly with the corresponding parameters of the two compartment model analysis (r = +0.892, r = +0.989 and r = +0.999, respectively). The initial disposition constant (α) and the rates of distribution of phenazone between the central and peripheral compartment, k₁₂ and k₂₁ were unaltered in the patients with liver disease, whereas the clearance was significantly reduced. These results confirm that the plasma clearance of phenazone is reliably investigated by sampling only from the terminal phase of the plasma elimination curve.     

The influence of enzyme induction on polymorphic sparteine oxidation.

The effects of antipyrine (1200 mg day-1), phenobarbitone (100 mg day-1) and rifampicin (600 mg and 1200 mg day-1, respectively) administration for 7 days on sparteine metabolism and 6 beta-hydroxycortisol excretion were studied in panels of extensive (EM) and poor metaboliser (PM) subjects. Drug metabolism was induced in both EM and PM subjects by antipyrine and rifampicin pretreatment as indicated by increased excretion of 6 beta-hydroxycortisol. A 30% increase in metabolic clearance of sparteine was observed in EM subjects following rifampicin administration whereas in PM subjects no effect on the overall elimination of the drug was seen. The data indicate that the regulation of cytochrome P-450 isozyme involved in polymorphic debrisoquine/sparteine metabolism is predominantly under genetic control and that enzyme induction exerts only a marginal effect.     

Influence of bed rest on the pharmacokinetics of phenazone

Summary The pharmacokinetics of a single dose of phenazone was studied in six subjects while ambulant and during bed rest for 3 days. Elimination of the drug was followed for 12 h after oral and intravenous administration. The elimination rate constant and total body clearance were significantly increased during bed rest as compared to the ambulant period, but the differences were small. The apparent volume of distribution decreased significantly. No consistent change due to bed rest was found in the rate of absorption or bioavailability of the oral dose.     

Postoperative disappearance of phenazone from plasma in man

Summary The elimination rate of phenazone after a single oral dose has been studied before and after elective operations. In a group of patients with different illnesses the elimination rate was increased on the fourth to seventh days after operation but was unchanged on the second and third days. The change in elimination rate was highly significant in a standardized group of nine patients with a ligament injury in one knee studied on the fourth or fifth postoperative day. Possible reasons for the changes are discussed.     

Effect of cannabis and certain of its constituents on pentobarbitone sleeping time and phenazone metabolism

1. Cannabis extract prolonged sleeping time in mice in a thermally neutral environment (30-32 degrees C) in which hypothermia does not occur. The prolongation was dose related, just detectable at 50 mg/kg, and 4-fold at 500 mg/kg.2. Under these conditions, ether sleeping time was not prolonged.3. Cannabis extract inhibited the aerobic metabolism of phenazone by a microsome-rich 9,000 g supernatant of mouse liver homogenate capable of nicotinamide adenine dinucleotide phosphate (NADPH) generation.4. Delta(1)-Tetrahydrocannabinol (Delta(1)-THC) prolonged pentobarbitone sleep and inhibited phenazone metabolism, but its action was limited, and could not account for the effect of the extract. The carotenes and water-soluble fractions of the extract were inactive on pentobarbitone sleep.5. Cannabidiol was strongly active by both tests; in vivo 39.8 muM/kg (12.5 mg/kg) prolonged sleep by 190%, and in vitro 12.7 muM inhibited phenazone metabolism 20%. These actions were dose related, and could account for the effect of the extract.6. The prolongation of pentobarbitone sleep by cannabis extract in a dose of 200 mg/kg, intraperitoneally, was maximal when given 30 min before the pentobarbitone, still present at 3 h, but undetectable at 24 hours. No phase of enhanced metabolism at 24 or 48 h after single cannabis injection was detected.7. It is concluded that cannabis extract inhibits microsomal activity of mouse liver, chiefly by virtue of its cannabidiol content. It is probable that cannabis consumption by man could lead to altered disposal of many other drugs, used in medicine or otherwise.     

Pharmacokinetics of phenazone (antipyrine) in rabbits with experimental common bile duct obstruction.

1. An altered functional state of liver due to experimental cholestasis could result in a change in the biotransformation of drugs. The aim of this study was to evaluate an influence of obstructive cholestasis on the pharmacokinetics of phenazone (antipyrine). 2. The investigation was carried out on male rabbits, randomly allocated into two groups: shamoperated and animals with biliary ducts ligation. Phenazone was administered intragastrically as a probe of drug metabolism. 3. Measurements, i.e. laboratory and pharmacodynamic tests, as well as pharmacokinetic assays, were performed before the operation as well as 10-12 days after the bile duct ligation. At the end of the study livers were examined macro- and microscopically and biochemical analysis of the liver microsomes was performed. 4. The measured pharmacokinetic parameters suggested an impaired biotransformation of phenazone in animals with obstructive cholestasis, leading to a slower drug elimination.     

Metabolomics study on the therapeutic effect of traditional Chinese medicine Xue-Fu-Zhu-Yu decoction in coronary heart disease based on LC-Q-TOF/MS and GC-MS analysis

The present study aims is to investigate the metabolic mechanism of Xue-Fu-Zhu-Yu decoction (XFZYD) in the treatment of blood-stasis syndrome in Coronary Heart Disease (CHD). To that end, 30 CHD patients with Blood-Stasis Syndrome (BSS) and 20 healthy subjects were enrolled. LC-Q-TOF/MS analysis determined that in comparison between CHD with BSS patients (Group A) and healthy subjects (Group C), 59 significantly differential metabolites in the positive mode and 18 significantly differential metabolites in the negative mode. The metabolite constituents in the plasma of 30 CHD with BSS patients before (group A) and after 30 days of treatment (Group B), and 20 healthy subjects (Group C) were analyzed using LC-Q-TOF/MS and GC-MS. Based on multivariate statistical analysis (PCA, PLS-DA and OPLS-DA), we determined 69 differential metabolites. The levels of hemorheology indexes were significantly down-regulated after treatment. Metabolic pathway attribution analysis showed that lipid metabolism, amino acid metabolism and bile acid metabolism pathways are involved. Our study identifies the metabolic networks of CHD and demonstrates the efficacy of this metabolomics approach to systematically study the therapeutic effect of XFZYC on CHD.     

Effect of acute and chronic exercise on hepatic drug metabolism

Recent research indicates that physical exercise and fitness are new host factors with impact on hepatic drug metabolism, contributing to the intra- and interindividual variation in drug response. Moderate to heavy physical exercise for a few hours reduces liver blood flow as assessed by indocyanine green clearance, leading to a decreased elimination of drugs exhibiting flow-limited metabolism (high clearance drugs) such as lignocaine (lidocaine). However, hepatic elimination of drugs exhibiting capacity-limited metabolism (low clearance drugs) such as antipyrine (phenazone), diazepam and amylobarbitone (amobarbital) is not affected by acute physical exercise. Improved physical fitness as expressed by the maximum oxygen uptake seems to increase the elimination rate of the low clearance drug antipyrine and possibly also aminopyrine, while investigations of the biotransformation of high clearance drugs are contradictory. The sum of research in this recent field is rather limited and the mechanism whereby changes in physical fitness influence hepatic drug metabolism needs to be established. It is not known if other liver functions are changed. If the findings also apply for drugs with a low therapeutic index, there may be a risk of exercise-induced changes in drug efficacy and toxicity. It is suggested that future studies on host factors influencing drug metabolism should include information on physical activity.     

Population Pharmacokinetic-Pharmacodynamic Model of Oral Fludrocortisone and Intravenous Hydrocortisone in Healthy Volunteers

This study aimed at describing the pharmacokinetics and the concentration-effect relationships of fludrocortisone and hydrocortisone on urinary sodium/potassium excretion in healthy volunteers. This was a placebo-controlled, randomized, double blind, crossover study, of oral fludrocortisone and intravenous hydrocortisone, given alone or in combination, in 12 healthy male volunteers. Nonlinear mixed-effects modeling was used to describe the pharmacokinetics and pharmacokinetic-pharmacodynamic relationships on urinary sodium/potassium ratio for each drug. A one-compartment model was used to describe fludrocortisone and hydrocortisone pharmacokinetics. Mean plasma half-life was 1.40 h (95%CI [0.80;2.10]) for fludrocortisone and 2.10 h (95%CI [1.78;2.40]) for hydrocortisone. Clearance was 40.8 L/h (95%CI [33.6;48]) for fludrocortisone and 30 L/h (95%CI [25.3;34.7]) for hydrocortisone. An indirect response model was used to describe effects on urinary sodium/potassium ratio. Fludrocortisone plasma concentrations showed a wider inter-individual dispersion than hydrocortisone plasma concentrations. Urinary sodium/potassium ratio variability was also higher with fludrocortisone as compared to hydrocortisone. The plasma concentration of drug producing 50% of maximal inhibition of urinary sodium/potassium (IC₅₀) was about 200 times lower for fludrocortisone (0.08 μg/L, 95%CI [0.035;0.125]) than for hydrocortisone (16.7 μg/L, 95%CI [10.5;22.9]). Simulations showed that a 4-time per day administration regimen allow to achieve steady fludrocortisone plasma concentrations with stable decrease in urinary sodium/potassium ratio after the second administration of fludrocortisone. Fludrocortisone and hydrocortisone have short and similar plasma elimination half-lives in healthy subjects. Fludrocortisone plasma concentrations and effect on urinary sodium/potassium ratio had a higher inter-individual variability as compared to hydrocortisone. The administration regimen of fludrocortisone should be reconsidered.     

Metabolic functions of the liver during chemotherapy in children with acute lymphoblastic leukemia.

OBJECTIVE: The purpose of the present work was estimation of liver function using the phenazone test and commonly used biochemical tests in children with acute lymphoblastic leukemia (ALL) during anticancer treatment. METHODS: Observations were carried out in the same 21 patients with ALL before the beginning of chemotherapy, after Protocol I and after Protocol M of the antileukemic treatment carried out according to the program BFM 86. RESULTS: The applied chemotherapy inhibited phenazone elimination. Both phenazone half-life and metabolic clearance rate were significantly different in patients after treatment with anticancer drugs, especially with high-dose of methotrexate (MTX), from those in patients before the beginning of chemotherapy (p < 0.001). Moreover, after MTX administration transaminases activity and serum bilirubin concentration were significantly higher than before treatment (p < 0.05). CONCLUSION: Our results showed that in children with acute lymphoblastic leukemia, anticancer chemotherapy decreased liver metabolic capacity. Particularly, high-dose methotrexate treatment altered the elimination of phenazone by inhibiting the activity of hepatic mixed function oxidase system. This change may lead to an increase in toxicity of active drugs which are metabolized by this enzyme system. In addition, altered activity of liver metabolic function can impair transformation of prodrugs to active forms. It should be considered in selection of individual drug dosages. The objective estimation of the type and degree of liver dysfunction can only be achieved by the combination of a quantitative phenazone dynamic test and static biochemical tests.     

Chloroquine disposition in hypersensitive and non-hypersensitive subjects and its significance in chloroquine-induced pruritus

Twenty-one healthy Nigerian volunteers distributed into four groups participated in a study to determine the significance of chloroquine disposition in chloroquine-induced pruritus. It involved the administration of chloroquine with or without promethazine pre-administration to the subjects. Group I consisted of 8 chloroquine non-hypersensitive subjects receiving 2 tablets of chloroquine sulphate (300 mg base); Group II consisted of 5 chloroquine non-hypersensitive subjects receiving 2 tablets of chloroquine sulphate 30 minutes after 25 mg promethazine tablet pre-administration; Group III consisted of 5 chloroquine hypersensitive subjects treated as in Group II; Group IV consisted of 3 hypersensitive subjects treated as in Group I. Blood (5 ml) and urine samples were collected periodically for up to 6 days post-dose. The samples were analysed for chloroquine and some of its oxidation metabolites by a specific HPLC method. Probit plots of cumulative drug/metabolite ratios were done to determine if there is polymorphism in chloroquine metabolism. There was bimodality only in the distribution of chloroquine/monodesethylchloroquine ratios, suggesting polymorphism in the metabolic oxidation of chloroquine in these subjects. Higher levels of monodesethylchloroquine were obtained in Group IV subjects when compared with any of the other groups. The oral clearance rate, elimination half-life, and volume distribution at steady state of chloroquine in the study groups were not significantly different (P greater than 0.05). In the absence of promethazine there appears to be an extensive metabolism of chloroquine in hypersensitive individuals to produce monodesethylchloroquine which probably determines the degree of pruritus experienced by an individual.     

Lack of impairment of fluocortolone disposition in oral contraceptive users

Summary Seven healthy women chronically (>6 months) treated with oral contraceptives and 7 age-and weight-matched female controls were studied. Each subject was given 20 mg fluocortolone orally and the plasma concentrations of total and unbound fluocortolone in multiple samples obtained during the following 24 h were determined by HPLC and equilibrium dialysis.In the subjects on oral contraceptives there was no significant change in total clearance, unbound clearance or volume of distribution at steady-state of total and unbound fluocortolone, but there was a significant increase in hydrocortisone concentration compared to the control subjects.It appears that the elimination of the synthetic corticoid fluocortolone was not impaired by chronic administration of contraceptive steroids.     

Effect of yogasanas on the visual and auditory reaction time

Visual and auditory reaction time (VRT, ART) was studied in 83 healthy male subjects of 30-40 years of age who had never practiced yogasanas before. These subjects were divided into two groups viz. Group A whose VRT and ART was determined after 1 hr. yogasanas and Group B whose ART and VRT was determined after 6 weeks yogasanas training programme. VRT and ART showed a significant reduction in Group A (P less than .05) and Group B (P less than .001).