In vitro effect of the antimalarial drug proguanil hydrochloride on viability and DNA damage in human peripheral blood lymphocytes

This study aimed to evaluate the effect of proguanil, a chemical substance used for treatment and prevention of malaria on viability and DNA integrity in human lymphocytes in vitro. Two different concentrations of proguanil obtained from the plasma concentrations were used: 130 ng/ml used for prophylactic treatment and 520 ng/ml used in treatment of malaria. Testing was done with and without metabolic activation. Viability of lymphocytes decreased in time and dose dependent manner. Comet assay parameters showed similar effects, indicating that some damage to DNA molecule can occur. Frequency of sister chromatid exchanges did not show significant deviation from the control samples. As for the proliferation kinetics no significant changes were noticed. Since majority of DNA damaging effect is induced after metabolic activation it is to be concluded that activity of proguanil is dependent upon the active metabolite cycloguanil and that monitoring should be conducted especially among frequent travellers.     

In vitro effect of the antimalarial drug proguanil hydrochloride on viability and DNA damage in human peripheral blood lymphocytes

This study aimed to evaluate the effect of proguanil, a chemical substance used for treatment and prevention of malaria on viability and DNA integrity in human lymphocytes in vitro. Two different concentrations of proguanil obtained from the plasma concentrations were used: 130ng/ml used for prophylactic treatment and 520ng/ml used in treatment of malaria. Testing was done with and without metabolic activation. Viability of lymphocytes decreased in time and dose dependent manner. Comet assay parameters showed similar effects, indicating that some damage to DNA molecule can occur. Frequency of sister chromatid exchanges did not show significant deviation from the control samples. As for the proliferation kinetics no significant changes were noticed. Since majority of DNA damaging effect is induced after metabolic activation it is to be concluded that activity of proguanil is dependent upon the active metabolite cycloguanil and that monitoring should be conducted especially among frequent travellers.     

In vitro evaluation of the cytotoxic and genotoxic effects of artemether,an antimalarial drug,in a gastric cancer cell line (PG100)

Artemisinin is a sesquiterpene lactone endoperoxide, obtained from Artemisia annua, and extensively used as an antimalarial drug. Many studies have reported the genotoxic and cytotoxic effects of artemisinins; however, there are no studies that compare such effects between cancer cell lines and normal human cells after treatment with artemether, an artemisinin derivative. Gastric cancer is the fourth most frequent type of cancer and the second highest cause of cancer mortality worldwide. Thus, the aim of this study was to evaluate the in vitro genotoxic and cytotoxic effects induced by artemether in gastric cancer cell line (PG100) and compare them with the results obtained in human lymphocytes exposed to the same conditions. We used MTT (3‐(4,5‐methylthiazol‐2‐yl)‐2, 5‐diphenyl‐tetrazolium bromide) assay, comet assay and ethidium bromide/acridine orange viability staining to evaluate the cytotoxic and genotoxic effects of artemether in PG100. MTT assay showed a decrease in the survival percentages for both cell types treated with different concentrations of artemether (P < 0.05). PG100 also showed a significant dose‐dependent increase in DNA damage index at concentrations of 119.4 and 238.8 µg ml^?1 (P < 0.05). Our results showed that artemether induced necrosis in PG100 at concentrations of 238.8 and 477.6 µg ml^?1, for all the tested harvest times (P < 0.05). In lymphocytes, artemether induced both apoptosis and necrosis at concentrations of 238.8 and 477.6 µg ml^?1, for all the tested harvest times (P < 0.05). In conclusion, human lymphocytes were more sensitive to the cytotoxic effects of the antimalarial drug than the gastric cancer cell line PG100. Copyright © 2011 John Wiley & Sons, Ltd.     

Assessment of the value of therapeutic monitoring of tacrine in Alzheimer's disease

Objectives: The purpose of this study was to validate the lower end of the putative therapeutic range of serum tacrine concentrations of 7–20?ng?·?ml^?1 in the treatment of Alzheimer's disease. Methods: The relationship between dose, steady-state serum tacrine concentrations and change in MMSE score (a measure of cognitive function) was examined in 106 Alzheimer's disease patients who had been treated with the drug for 12 weeks. Results: In all, 72% of patients showed some response, but there was no relationship between dose and the chance of a favourable outcome. The proportion of patients with serum concentrations above 7?ng?·?ml^?1 who improved (79%) was significantly greater than that of those with serum concentrations below this level (47%) (P?<?0.02). Also, a significantly greater proportion of patients with serum concentrations above both 5?ng?·?ml^?1 and 9?ng?·?ml^?1 showed improvement in comparison to those with concentrations below these levels. Conclusions: This study indicates that therapeutic monitoring of serum tacrine concentrations might increase the possibility of responding to tacrine by some 68%. This represents an important contribution to the management of Alzheimer's disease patients with this drug, and may also be relevant to the use of the newer generation of cholinesterase inhibitors.     

Delivery of atovaquone and proguanil across sublingual membranes,in vitro

Malarone^?, a combination of atovaquone (AT) and proguanil (PR), is indicated for the prophylaxis and treatment of uncomplicated Plasmodium falciparum malaria. This study aimed to determine in vitro the feasibility of delivering the combination of AT and PR as a spray formulation via the sublingual route, using Franz diffusion cells incorporating porcine sublingual mucosa. Firstly, 1?mg mL^?1 of each drug in 20% 1,8-Cineole in ethanol was used; and secondly, 5?mg mL^?1 AT and 1?mg mL^?1 PR in 20% 1-methyl-2-pyrrolidone in ethanol was examined, dosed every 2?h over a 12-h period and receptor phase samples were analyzed by HPLC. From the first study, mean fluxes for AT and PR were 12.89?±?1.2 and 5.88?±?0.9 µg cm^?2 h^?1 respectively; pharmacokinetic calculations indicated that these fluxes were insufficient to achieve the target plasma concentrations for AT and PR of 1.4 µg mL^?1 and 200?ng mL^?1 respectively, in the treatment of falciparum malaria. However, in the second study, the fluxes of AT and PR increased to 50.92?±?20.8 and 12.01?±?1.5 µg cm^?2 h^?1 respectively, and pharmacokinetic calculations indicated that therapeutic plasma concentrations are attainable for pediatric application.     

LC-MS-MS analysis of 2-pyridylacetic acid,a major metabolite of betahistine: application to a pharmacokinetic study in healthy volunteers

1.?A sensitive liquid chromatographic-tandem mass spectrometric assay was developed and validated to determine the major metabolite of betahistine, 2-pyridylacetic acid, in human plasma.

2.?The analyte was extracted from plasma samples by liquid–liquid extraction and analysed using liquid chromatography-tandem mass spectrometry with an electrospray ionization interface. The method has a lower limit of quantitation of 1?ng?ml^?1 for a 0.5-ml plasma aliquot. The intra- and interday precision (relative standard deviation), calculated from quality control (QC) samples, was less than 10%. Accuracy as determined from QC samples was within ±7%.

3.?The validated method was successfully applied to a pharmacokinetic study of betahistine in healthy volunteers. After oral administration of a single dose of 24?mg betahistine mesylate to 20 healthy Chinese male volunteers, C_max was 339.4?ng?ml^?1 (range 77.3–776.4?ng?ml^?1). The t_1/2 was 5.2?h (range 2.0^?1?11.4?h). The AUC_0?t obtained was 1153.5?ng?ml^?1?h (range 278.5–3150.8?ng ml^?1?h). The disposition of the metabolite exhibited a marked interindividual variation.

4.?The plasma concentrations of the parent drug were less than 0.5?ng ml^?1, suggesting that it undergoes almost complete first-pass metabolism. The reported two active metabolites were not detected in the plasma of any volunteer. Although there is no evidence that the major metabolite has pharmacological activity, the clinical importance of 2-pyridylacetic acid in humans should be reinvestigated.     

Plasma concentrations and bioavailability of isosorbide dinitrate and pindolol from a combination formulation

The plasma concentrations and bioavailability of sustained-release isosorbide denigrate and standard-release pindolol have been compared after administration of these drugs in combination and alone. Bioavailability parameters of isosorbide dinitrate and pindolol obtained after administration of the drugs in combination were not significantly different (P>0.05) to those obtained after administration of either drug alone. Two peaks of mean concentrations of isosorbide dinitrate occurred in plasma after administration of 30 mg of this drug in combination with 7.5 mg pindolol (4.4 ng ml^?1 at 1 h and 4.5ng ml^?1 at 5h), or alone (5.9ngml^?1 at 2h and 5.7ng ml^?1 at 5h). In each case, plasma concentrations of isosorbide dinitrate were maintained during at least 8 h, whereas the drug was not detected in plasma at 2.5 h after administration of a standardrelease formulation. The peaks of mean concentrations of pindolol were 39.7ng ml^?1 at l.5h after administration of 7.5 mg drug in combination with isosorbide dinitrate and 38.0 ng ml^?1 at 1 h after administration of the drug alone. Concentrations of pindolol in plasma declined with a half-life of 3 h.     

Assessment of the genotoxic effects of organophosphorus insecticides phorate and trichlorfon in human lymphocytes

In vitro genotoxic effects of organophosphorus insecticides Phorate (PHR) and Trichlorfon (TCF) were investigated using four genotoxicity endpoints. Different concentration ranges between 0.25–2.00 μg mL^?1 of PHR and 2.34–37.50 μg mL^?1 of TCF were applied to lymphocytes. PHR and TCF significantly increased the frequency of chromosomal aberrations (except 2.34 μg mL^?1 for TCF) and sister chromatid exchanges at all treatment times and concentrations. Most of the used concentrations induced a significant increase in the frequency of micronuclei. Furthermore, PHR and TCF significantly decreased the mitotic index at the higher concentrations after 24‐ and 48‐h treatments. In the comet assay, PHR and TCF significantly increased the comet tail at all concentrations. However, the comet tail intensity was significantly increased at only the highest concentration of PHR and at all concentrations of TCF. According to these results, PHR and TCF possess clastogenic, mutagenic, and DNA damaging effects in human lymphocytes in vitro. © 2012 Wiley Periodicals, Inc. Environ Toxicol 29: 577–587, 2014.     

Atovaquone resistance in malaria parasites

Atovaquone is a broad-spectrum antiparasitic agent active against malaria, Pneumocystis carinii pneumonia, toxoplasmosis and babesiosis. When used as a single agent, resistance to atovaquone arose rapidly in falciparum malaria, requiring the development of a new antimalarial drug combination of atovaquone and proguanil. Recent laboratory investigations have provided insights into the mode of atovaquone action, and identified the molecular basis for the resistance development. Mutations within a catalytic domain of the cytochrome bc₁complex present within the parasite mitochondrial inner membrane were shown to be responsible for atovaquone resistance. Here, we review these studies and propose a mechanism by which atovaquone resistance may arise quickly in malaria parasites.     

Plasma and cerebrospinal fluid concentrations of pentazocine in patients: assay by mass fragmentography

Mass fragmentography has been used for the determination of low concentrations of pentazocine in blood plasma and cerebrospinal fluid (csf) after intravenous administration of a 30 mg dose to eight patients undergoing neurosurgery under general anaesthesia. A pharmacokinetic analysis based upon mean plasma levels indicated a half-life of 134 min. Lumbar csf levels of pentazocine increased rapidly with mean values from about 3 ng ml^?1 at 5 min to 10 ng ml^?1 at 30 min and to about 15 ng ml^?1 at 90–120 min. The possibility of repeated analyses of drug concentrations in the csf represents an important step towards the correlation of chemical data with clinical effects for centrally acting drugs.     

Physiologically based modeling of p‐tert‐octylphenol kinetics following intravenous,oral or subcutaneous exposure in male and female Sprague–Dawley rats

The objective of this study was to develop a physiologically based pharmacokinetic (PBPK) model for p‐tert‐octylphenol (OP) for understanding the qualitative and quantitative determinants of its kinetics in Sprague–Dawley rats. Compartments of the PBPK model included the liver, richly perfused tissues, poorly perfused tissues, reproductive tissues, adipose tissue and subcutaneous space, in which OP uptake was described as a blood flow‐ or a membrane diffusion‐limited process. The PBPK model successfully simulated previously published data on blood and tissue OP concentrations in Sprague–Dawley rats following oral, intravenous (i.v.) or subcutaneous (s.c.) routes. The model predicted that OP concentrations would reach 6.8, 13.8 and 27.9 ng ml^?1 (male) and 7.2, 14.7 and 31.4 ng ml^?1 (female), 4 h after a single i.v. dose of 2, 4 and 8 mg kg^?1, respectively. The model also predicted that OP concentrations would reach 53.3, 134.8 and 271.2 ng ml^?1 (male) and 87.4, 221.4 and 449.7 ng ml^?1 (female) 4 h after a single oral dose (50, 125 and 250 mg kg^?1) and that, 4 h after a single s.c. dose (125 mg kg^?1), OP concentrations would reach 111.3 ng ml^?1 (male) and 121.6 ng ml^?1. A marked sex difference was seen in blood and tissue OP concentrations. This was reflected in the model by a gender‐specific maximal velocity of metabolism (V_max) that was higher (1.77×) in male than in female rats. Further studies are required to elucidate the mechanism underlying the gender differences and to evaluate whether that is also observed in humans. Copyright © 2010 John Wiley & Sons, Ltd.     

Clomipramine concentration as a predictor of delayed response: a naturalistic study

Objectives: The aim of the present study was to characterise onset of response to clomipramine treatment in a naturalistic setting and to investigate the relationship between concentration and delayed response, postulated to reflect drug-specific response to antidepressant therapy. Methods: Ninety-eight depressed patients were prescribed clomipramine in an open flexible manner and followed for depressive symptoms (Montgomery-Åsberg depression scale) over a maximum 12 weeks follow-up period. All patients had at least one concentration measurement for therapeutic drug monitoring purpose. Results: Firstly, survival analysis revealed a probability of 15.4% for patients not to show 50% improvement over baseline by week 12, and thus to be considered as non-responders. Median time to onset of response was 31 days for responders, indicating a relatively high probability of delayed response under routine treatment. Secondly, pattern analysis indicated a significant association between early and abrupt response on the one hand and delayed and gradual response on the other. A tendency towards an association between delayed and persistent response was also observed. Finally, receiver operating characteristics analysis allowed identification of a highly significant lower threshold of 230?ng?·?ml^?1 for the sum of clomipramine and desmethyl-clomipramine, as measured at week 3, with respect to response from week 3 onward. Predictive values were 68.8% and 81.0% for concentrations above and below this threshold to predict delayed response and non-response, respectively. Thresholds were 55?ng?·?ml^?1 for parent compound and 180?ng?·?ml^?1 for metabolite. Conclusion: This approach supports the hypothesis that delayed response may be concentration dependent and thus may reflect true drug effect. As a consequence, monitoring clomipramine concentration about 3 weeks after initiation of therapy may valuably contribute to help clinicians decide about the adequacy of ongoing therapy.     

Evaluation of the genotoxic and antigenotoxic potential of Baccharis dracunculifolia extract on V79 cells by the comet assay

Baccharis dracunculifolia (Asteraceae), the main botanical source of green propolis, is a shrub of the Brazilian ‘cerrado’. In folk medicine it is used as an anti‐inflammatory agent, mainly for the treatment of gastrointestinal diseases. The aim of the present study was to evaluate the genotoxic and antigenotoxic effects of B. dracunculifolia ethyl acetate extract (Bd‐EAE) on Chinese hamster lung fibroblasts (V79 cells) by the comet assay. Methyl methanesulfonate (MMS; 200 μM ) was used as an inducer of DNA damage. Genotoxicity was evaluated using four different concentrations of Bd‐EAE: 12.5, 25.0, 50.0 and 100.0 μg ml^?1. Antigenotoxicity was assessed before, simultaneously, and after treatment with the mutagen. The results showed a significant increase in the frequency of DNA damage in cultures treated with 50.0 and 100.0 μg ml^?1 Bd‐EAE. Regarding its antigenotoxic potential, Bd‐EAE reduced the frequency of DNA damage induced by MMS. However, this chemopreventive activity depended on the concentrations and treatment regimens used. The antioxidant activity of phenolic components present in Bd‐EAE may contribute to reduce the alkylation damage induced by MMS. In conclusion, our findings confirmed the chemopreventive activity of Bd‐EAE and showed that this effect occurs under different mechanism. Copyright © 2009 John Wiley & Sons, Ltd.     

Pharmacokinetics of isosorbide dinitrate after intravenous infusion in human subjects

Plasma concentrations of isosorbide dinitrate have been measured after intravenous infusion of drug at a rate of 5·0 mg h^?1 for 150 min and after single equal oral doses of 12·5 mg of drug in solution to two normal human subjects. During the infusion, uneven plateau concentrations were approached after 30 min. The calculated average steady-state plasma levels were 258 ng ml^?1 and 514 ng ml^?1 in the two subjects respectively. The half-life of elimination of isosorbide dinitrate after termination of the infusion was 9–10 min. After oral doses, peak plasma levels of 26·6 ng ml^?1 and 12·7 ng ml^?1 occurred at 10 min and 20 min in the two subjects respectively. The terminal half-life of drug after the oral doses was much longer than the elimination half-life (about 10 min), and was associated with the absorption phase. Fairly good agreement was obtained between the observed concentrations and those predicted by a one-compartment open model. The systemic availability of isosorbide dinitrate after the oral doses was up to only 3 per cent of the equal doses infused, indicating that presystemic elimination processes accounted for very large proportions of the oral doses. The systemic clearances of drug after infusion of 0·32 1 min^?1 and 0·161 min^?1 were unexpectedly low for a drug of reported high liver extraction ratio.     

Measurement of plasma concentrations of isosorbide dinitrate

Concentrations of the vasodilator isosorbide dinitrate (ISDN) in human plasma can be measured with good sensitivity (about 0·2–0·5 ng ml^?1) using electron-capture gas chromatography after a one-stage extraction. The mean recovery of ISDN from plasma was 83 per cent ± 9 standard deviation (S.D.). The precision of the method for the measurement of ISDN in plasma ranged from ± 14 per cent at 1 ng ml^?1 to ± 7 per cent at 5 ng ml^?1 to ± 4 per cent at 50 ng ml^?1. The 95 per cent confidence limits of the least-squares regression calibration line forced through the origin were ± 100 per cent at 1 ng ml^?1, ± 11 per cent at 10 ng ml^?1, and ± 8 per cent at 30 ng ml^?1. The method has been used to assay many samples withdrawn after doses of drug at therapeutic levels to normal subjects.     

Lack of a pharmacokinetic interaction between atovaquone and proguanil

Objective: To assess the magnitude of the putative effect of atovaquone on the pharmacokinetics of proguanil and to determine whether the pharmacokinetics of atovaquone are affected by concomitant administration of proguanil, with both drugs administered for 3 days to healthy adult volunteers. Methods: This was an open-label, randomized, three-way cross-over study, in which 18 healthy volunteers received 400 mg proguanil, 1000 mg atovaquone and 1000 mg atovaquone + 400 mg proguanil. Each treatment was given once daily for 3 days with a 3-week wash-out period between each occasion. For the assay of proguanil, cycloguanil and atovaquone, blood was sampled before dosing and at regular intervals over 8 days when proguanil was given, and over 17 days when atovaquone was given. Results: The geometric mean of the area under the atovaquone plasma concentration-time curve calculated from 0 to 24 h after the last dose (AUC_0→24h) was 180 μg · ml⁻¹ · h following administration of atovaquone alone and 193 μg · ml⁻¹ · h following atovaquone with proguanil. The geometric mean AUC_0→24h for proguanil was 6296 ng · ml⁻¹ · h after proguanil alone and 5819 ng · ml⁻¹ · h following proguanil with atovaquone. The corresponding values for the metabolite cycloguanil were 1297 ng · ml⁻¹ · h and 1187 ng · ml⁻¹ · h, respectively. The geometric mean elimination half-life (t_1/2) of atovaquone was 57.1 h when given alone and 59.0 h when administered together with proguanil. The corresponding geometric mean values of t_1/2 for proguanil were 13.7 h and 14.5 h. Exploratory statistical analysis showed no important gender effects on the pharmacokinetics of atovaquone, proguanil, or cycloguanil. Conclusion: The pharmacokinetics of atovaquone and proguanil and its metabolite, cycloguanil, were not different when atovaquone and proguanil were given alone or in combination. Received: 14 October 1998 / Accepted in revised form: 8 February 1999     

Nonlinear elimination and hepatic concentration of conjugation- metabolite of valproate in guinea-pigs

The plasma clearance and metabolic rate characteristics of valproic acid (VPA) were studied using guinea-pigs placed on various (0.08-9 μmol ml^?1 = 11–1303 μg ml^?1) steady-state plasma concentrations (C_ss) by constant intravenous (i.v.) infusion. The total clearance (CL) was significantly decreased at plasma concentration of 0.61 μmol ml^?1 (88 μg ml^?1). The metabolic clearance of VPA was apparently biphasic. The maximum metabolic rate (V_max) and the Michaelis-Menten constant (K_m) for the primary (V_maxl, K_ml) and the secondary (V_max2, K_m2) pathways were V_maxl = 1.52 μmol min ^?1kg^?1, K_ml = 0.15 μmol ml^?1, V_max2 = 24.98 μmol min ^?1 kg^?1 and K_m2 = 11.70 μmol ml^?1, respectively. The K_ml value was within clinical therapeutic concentration range. The formation of conjugated VPA (cjVPA) metabolite in liver was shown to be saturable. Plasma protein binding of VPA was also nonlinear. The dose-dependent decrease in metabolic clearance was counterbalanced by the increased unbound fraction (f_u), resulting in a relatively constant apparent clearance of VPA over a wide concentration range. The hepatic concentration of VPA was not significantly different from the plasma unbound concentration, again over a wide concentration range. The biliary and hepatic concentrations of VPA were not significantly different; but the concentration ratio of cjVPA in bile compared with that of VPA in liver decreased against hepatic concentration of VPA, which suggests a saturable conjugation rate. The K_m value estimated from hepatic cjVPA production as a function of plasma VPA concentration was comparable with the K_ml value. These results implied that the primary metabolic parameters may describe the conjugation pathway which is nonlinear within the clinical therapeutic concentration range.     

Atovaquone + proguanil: new preparation. Second-line antimalarial combination

(1) Quinine, halofantrine and mefloquine are effective treatments for most cases of uncomplicated Plasmodium falciparum malaria. (2) The choice of drug for prevention of P. falciparum malaria in highly endemic regions depends on the risk of chloroquine resistance, and possibly mefloquine resistance. The reference treatments are the chloroquine + proguanil combination, and mefloquine. (3) Marketing authorisation has been granted in France for the atovaquone + proguanil combination, in curative and preventive treatment of P. falciparum malaria. (4) The efficacy of the atovaquone + proguanil combination in uncomplicated malaria is similar to that of other treatments. Some strains of malaria seem to have reduced sensitivity. (5) The atovaquone + proguanil combination is also effective as prophylaxis, but there are no clinical trials showing whether it is equivalent to or better than other preventive treatments in non immune travellers. (6) According to the French licensing terms, atovaquone + proguanil prophylaxis can be stopped 7 days after leaving an endemic area, rather than 3-4 weeks with other drugs. This recommendation is based on weak evidence: mainly on theoretical arguments and on the absence of clinical malaria in some patients with evidence of P. falciparum infection. (7) The atovaquone + proguanil combination is less effective against other Plasmodium species (P. malariae, P. ovale and P. vivax). Chloroquine remains the reference treatment for these forms of malaria, which do not carry a risk of serious complications. (8) There were few adverse events in people taking the atovaquone + proguanil combination during clinical trials. During curative treatment, this combination caused more nausea and vomiting than reference treatments, while, in the prophylactic setting, it had slightly fewer adverse effects than the chloroquine + proguanil combination or mefloquine alone. But the drop out rate was not significantly different between treatment groups. (9) Atovaquone should be taken with food, to improve absorption. (10) The atovaquone + proguanil combination is expensive and is not refunded in France. In contrast, curative treatment with quinine is cheap, and is fully refunded. (11) Mefloquine and quinine remain the treatments of choice for uncomplicated malaria where there is chloroquine resistance. The atovaquone + proguanil combination is useful if mefloquine and quinine are contraindicated; unlike halofantrine, this combination does not carry the risk of serious drug interactions. In the prophylactic setting, the lack of experience with atovaquone means it should only be used as a second line option, after mefloquine, for short-term prophylaxis in areas with a high prevalence of chloroquine resistance.     

Pharmacokinetics of acetylmethadols I: Gas-liquid chromatographic determination of L-α-acetylmethadol and its major metabolites in plasma

A gas chromatographic method is reported for simultaneously determining acetyl-methadol, noracetylmethadol, and dinoracetylmethadol in plasma. Minimum detectable concentrations are 10 ng ml^?1 for acetylmethadol using a flame ionization detector, and 5 and 25 ng ml^?l for noracetylmethadol and dinoracetylmethadol respectively using electron capture detection. Extraction efficiency is quantitative for acetylmethadol but lower for the metabolites. The method is useful for monitoring drug levels following therapeutic doses of acetylmethadol.     

Ciprofibrate treatment in patients with atherogenic lipoprotein phenotype: effects on HDL quality, LDL susceptibility to oxidation and DNA damage

Objectives: This study was conducted to examine a complex effect of ciprofibrate therapy in patients with atherogenic lipoprotein phenotype. Methods: Effects of ciprofibrate were studied on HDL subpopulations, HDL ability to esterify cholesterol (FER_HDL), susceptibility of LDL to oxidation as well as on in vivo oxidative DNA damage in peripheral lymphocytes, measured as strand breaks (SBs) by the comet assay. Results: Ciprofibrate treatment significantly decreased total cholesterol, and triglycerides, and increased HDL-cholesterol. The FER_HDL showed a significant reduction (29.5?±?7.4 to 23?±?7.5%?·?h^?1, P?=?0.0001). The relative concentrations of HDL subclasses did not differ between baseline and after treatment. Ciprofibrate induced a significant increase in LDL oxidation lag time (93?±?7 to 102?±?11?min, P?=?0.02) and a decrease in DNA strand breaks (34.0?±?16.2 to 17.8?±?7.5, P?=?0.02). A significant correlation between maximal rate of diene production and strand breaks was found (r?=?0.55, P?=?0.01). These findings may be explained by an improvement of LDL resistance to oxidation, resulting in a decrease in oxidatively modified LDL's cytotoxic effect. Conclusion: Ciprofibrate treatment favourably affected the quality of plasma HDL, probably by the improvement of triglyceride rich lipoprotein metabolism and/or LDL subpopulation profile, increased LDL resistance to oxidation, and decreased the level of DNA damage in peripheral lymphocytes.