Biomedical subjects

K K Manouilov

Publications and source records attributed to K K Manouilov.

9 recordsLinked to original sources

PubMed1998

Colorimetric determination of hydroxyurea in human serum using high-performance liquid chromatography.

A high-performance liquid chromatography assay for hydroxyurea in human serum was developed based on a commercial colorimetric assay kit for urea (Sigma Diagnostics). Serum (0.5 ml), spiked with methylurea as an internal standard, was treated with 70% perchloric acid. Supernatant (0.2 ml) was combined with 0.7 ml of BUN acid reagent and 0.6 ml of BUN color reagent. The resulting colored reactant (100 microl) was analyzed on a 300 x 3.9 mm Bondclone 10 C18 column coupled with a UV-Vis detector, at 449 nm. The mobile phase was 13% acetonitrile in water. Retention times of colored derivatives of hydroxyurea and methylurea were 6.5 and 12.2 min, respectively. The log-log calibration curve was linear from 0.0065 to 1.31 mM. Average accuracy was 99.9+/-4.0% and the intra- and inter-day error of assay did not exceed 11%.

Chromatography, High Pressure Liquid↗

PubMed1998

Assay for etoposide in human serum using solid-phase extraction and high-performance liquid chromatography with fluorescence detection.

An HPLC assay for etoposide in human serum was developed. Serum, spiked with podophyllotoxin (internal standard), was treated with sodium dodecyl sulphate prior to solid phase extraction. Analysis was performed on a 300x3.9 mm Bondclone 10 C18 column coupled with a fluorometric detector (lambda(ex) 230 nm, lambda(em) 330 nm). The retention times for etoposide and podophyllotoxin were 14 and 28 min respectively. The range of assay was 0.5 to 20 microg/ml with a detection limit of 0.2 microg/ml. This assay is suitable for use in clinical studies with etoposide.

Antineoplastic Agents, Phytogenic↗

PubMed1997

High-performance liquid chromatographic determination of (-)-beta-D-2-aminopurine dioxolane and (-)-beta-D-2-amino-6-chloropurine dioxolane, and their metabolite (-)-beta-D-dioxolane guanine in monkey serum, urine and cerebrospinal fluid.

(-)-beta-D-2-Aminopurine dioxolane (APD), (-)-beta-D-2-amino-6-chloropurine dioxolane (ACPD) and dioxolane guanine (DXG) are nucleoside analogues possessing potent activity against human immunodeficiency virus (HIV) and hepatitis B virus (HBV) in vitro. APD and ACPD are metabolized in vivo to yield DXG. Reversed-phase HPLC analytical methodologies were developed for the simultaneous determination of APD and DXG, and for ACPD and DXG in monkey serum, urine and cerebrospinal fluid (CSF). 2-Fluoro-2',3'-dideoxyinosine (FDDI) served as the internal standard. The extraction recoveries of the nucleoside analogues from serum samples were similar, averaging approximately 90%. The limit of quantitation of the analytical method for serum samples was 0.1 microg/ml for DXG, and 0.25 microg/ml for APD and ACPD. The intra- and inter-day relative standard deviations for each compound at low, medium and high nucleoside concentrations were less than 9.0%. The accuracy of the assay methods was greater than 90% for prodrugs and parent compound. Similar results were observed with urine and CSF samples. Thus, these methods provide sensitive, accurate and reproducible determination of the prodrugs and parent nucleoside in biological samples.

Animals↗

PubMed1997

Lymphatic targeting of anti-HIV nucleosides: distribution of 2',3'-dideoxyinosine after intravenous and oral administration of dipalmitoylphosphatidyl prodrug in mice.

In the search for prodrugs of 2',3'-dideoxyinosine (ddI) with potential for improving the delivery of the nucleoside analogue to the lymphatic system, we synthesized dipalmitoylphosphatidyl-2',3'-dideoxyinosine (DPP-ddI) and its pharmacokinetics were investigated in mice. The disposition of ddI in plasma and lymph nodes was examined following intravenous and oral administration of parent nucleoside (100 mg/kg) and DPP-ddI (400 mg/kg, equivalent to 100 mg/kg of ddI). Concentrations of ddI were determined by HPLC. Pharmacokinetic parameters were estimated by area/moment analysis. Intravenous administration of DPP-ddI resulted in a pattern of lower peak concentrations of ddI and more sustained exposure of parent nucleoside in plasma and lymph nodes compared to administration of the parent nucleoside. Both ddI and DPP-ddI yielded similar AUC values in lymph nodes. Oral administration of the prodrug resulted in lower concentrations and AUC values of ddI in plasma and lymph nodes when compared to administration of the parent nucleoside. The bioavailability of ddI following ddI and DPP-ddI administration was 15 and 8%, respectively. The results of the present study demonstrate that DPP-ddI administered intravenously shows potential for targeting and sustaining level of ddI in the nodular lymphatic tissues.

Administration, Oral↗

PubMed1997

Biotransformation and pharmacokinetics of prodrug 9-(beta-D-1,3-dioxolan-4-yl)-2-aminopurine and its antiviral metabolite 9-(beta-D-1,3-dioxolan-4-yl)guanine in mice.

9-(beta-D-1,3-Dioxolan-4-yl)guanine (DXG) exhibits potent antiviral activity against human immunodeficiency virus type 1 (HIV-1) and hepatitis B virus (HBV) in vitro. However, since DXG possesses limited aqueous solubility, a more water soluble prodrug of DXG, 9-(beta-D-1,3-dioxolan-4-yl)-2-aminopurine (APD), was synthesized. The purpose of this study was to characterize the pharmacokinetics of APD and its antiviral metabolite DXG in mice. Female NIH-Swiss mice were administered 100 mg/kg APD intravenously or orally. Serum, brain and liver were collected at selected times following prodrug administration and concentrations of APD and DXG were determined by HPLC. APD was efficiently converted to parent nucleoside DXG following both intravenous and oral administration. Biotransformation of APD to DXG likely occurs in the liver and is mediated by xanthine oxidase. Similar pharmacokinetic profiles for DXG were observed following either route of administration in serum, liver and brain. These results demonstrate that APD appears to be a promising prodrug for the delivery of DXG.

2-Aminopurine↗

PubMed1996

Synthesis, biotransformation, and pharmacokinetic studies of 9-(beta-D-arabinofuranosyl)-6-azidopurine: a prodrug for ara-A designed to utilize the azide reduction pathway.

As a part of our efforts to design prodrugs for antiviral nucleosides, 9-(beta-D-arabinofuranosyl)-6-azidopurine (6-AAP) was synthesized as a prodrug for ara-A that utilizes the azide reduction biotransformation pathway. 6-AAP was synthesized from ara-A via its 6-chloro analogue 4. The bioconversion of the prodrug was investigated in vitro and in vivo, and the pharmacokinetic parameters were determined. For in vitro studies, 6-AAP was incubated in mouse serum and liver and brain homogenates. The half-lives of 6-AAP in serum and liver and brain homogenates were 3.73, 4.90, and 7.29 h, respectively. 6-AAP was metabolized primarily in the liver homogenate microsomal fraction by the reduction of the azido moiety to the amine, yielding ara-A. However, 6-AAP was found to be stable to adenosine deaminase in a separate in vitro study. The in vivo metabolism and disposition of ara-A and 6-AAP were conducted in mice. When 6-AAP was administered by either oral or intravenous route,the half-life of ara-A was 7-14 times higher than for ara-A administered intravenously. Ara-A could not be found in the brain after the intravenous administration of ara-A. However, after 6-AAP administration (by either oral or intravenous route), significant levels of ara-A were found in the brain. The results of this study demonstrate that 6-AAP is converted to ara-A, potentially increasing the half-life and the brain delivery of ara-A. Further studies to utilize the azide reduction approach on other clinically useful agents containing an amino group are in progress in our laboratories.

Animals↗

PubMed1996

In vitro and in vivo evaluation of 6-azido-2',3'-dideoxy-2'-fluoro-beta-D-arabinofuranosylpurine and N6-methyl-2',3'-dideoxy-2'-fluoro-beta-D-arabinofuranosyladenine as prodrugs of the anti-HIV nucleosides 2'-F-ara-ddA and 2'-F-ara-ddI.

In an effort to improve the pharmacokinetic properties and tissue distribution of 2'-F-ara-ddI, two lipophilic prodrugs, 6-azido-2'-3'-dideoxy-2'-fluoro-beta-D- arabinofuranosylpurine (FAAddP, 4) and N6-methyl-2'-3'-dideoxy-2'-fluoro-beta-D-arabinofuranosyladenine (FMAddA, 5), were synthesized and their biotransformation was investigated in vitro and in vivo, in mice. Compounds 4 and 5 were synthesized via the intermediate 2. For the in vitro studies, FAAddP and FMAddA were incubated in mouse serum, liver homogenate, and brain homogenate. FAAddP was metabolized in liver homogenate by the reduction of the azido to the amino moiety followed by deamination, yielding 2'-F-ara-ddI. The conversion of FAAddP to 2'-F-ara-ddA was mediated by microsomal P-450 NADPH reductase system, as shown by the liver microsomal assay. FAAddP was also converted to 2'-F-ara-ddI at a slower rate in the brain than in the liver. FMAddA, however, was stable in brain homogenate and was slowly metabolized in the liver homogenate. Metabolic conversion of FMAddA in vitro was stimulated by the addition of adenosine deaminase. In the in vivo metabolism study, FAAddP underwent reduction to 2'-F-ara-ddA followed by deamination to 2'-F-ara-ddI. FMAddA did not result in increased brain delivery of 2'-F-ara-ddI in vivo, probably due to the slow conversion as observed in the in vitro studies. However, there was an increase in the half-life of 2'-F-ara-ddI produced from FMAddA. This report is the first example in the design of prodrugs using the azido group for adenine- and hypoxanthine-containing nucleosides. This interesting and novel approach can be extended to other antiviral and anticancer nucleosides.

Animals↗

PubMed1996

Nucleoside conjugates. 15. Synthesis and biological activity of anti-HIV nucleoside conjugates of ether and thioether phospholipids.

A series of the anti-HIV nucleoside conjugates of either (1-O-alkyl) and thioether (1-S-alkyl) lipids linked by a pyrophosphate diester bond has been synthesized as micelle-forming prodrugs of the nucleosides to improve their therapeutic efficiency. These include AZT 5'-diphosphate-rac-1-S-octadecyl-2-O-palmitoyl-1-thioglycerol (1), 3'-azido-2',3'-dideoxyuridine 5'-diphosphate-rac-1-S-octadecyl-2-O-palmitoyl-1-thioglycerol (2) 2',3'-dideoxycytidine 5'-diphosphate-rac-1-S-octadecyl-2-O-palmitoyl-1-thioglycerol (3), and AZT 5'-diphosphate-rac-1-O-tetradecyl-2-O-palmitoylglycerol (4). The conjugates form micelles by sonication (mean diameters ranging 6.8-55.5 nm). Conjugate 1 protected 80% of HIV-infected CEM cells as low as 0.58 microM and lost the protection at 180 microM due to prevailing cytotoxicity, while the conjugate started to show the cytotoxicity at 100 microM. Pharmacokinetics studies showed a significant increase of half-life values (t1/2) of AZT and AZddU2 (respective t1/2 = 5.69 and 6.5 h) after administration of conjugates 1 and 2, while those after administration of AZT and AZddU were 0.28 and 0.89 h, respectively. The fractions of the prodrugs 1 and 2 converted to the parent compounds AZT and AZddU were 36% and 55%, respectively. The results indicate that AZT and AZddU thioether lipid conjugates 1 and 2 warrant further investigation.

Animals↗

PubMed1995

Lymphatic distribution of 3'-azido-3'-deoxythymidine and 3'-azido-2',3'-dideoxyuridine in mice.

Recently, it was shown that human immunodeficiency virus (HIV)-infected cells preferentially locate in lymphoid tissue early in the course of infection. Therefore, it is important to characterize the disposition of the anti-HIV agents, 3'-azido-3'-deoxythymidine (AZT) and 3'-azido-2', 3'-dideoxyuridine (AZdU), in the lymphatic system. The disposition of AZT and AZdU in serum and neck, axillary, and mesenteric lymph nodes was studied in mice after intravenous, oral, and intraperitoneal administrations of 50 mg/kg doses. Samples were collected at 0.08, 0.5, 1, 2, 3, 4, and 6 hr after dosing and nucleoside concentrations were determined by HPLC. Pharmacokinetic parameters were estimated using noncompartmental analysis. Maximum concentration, half-life, and area under the serum concentration vs. time curve (AUC) obtained from the serum concentration data were similar for both compounds after intravenous and intraperitoneal administrations; however, a difference in oral bioavailability for AZT and AZdU (49% and 76%, respectively) was noted. Patterns of regional distribution in lymph nodes were similar for both drugs; however, the accumulation of AZdU in the various lymph nodes, according to AUC values, was 3-76% greater than that for AZT. The relative exposure re = AUClymph/AUCserum) of both nucleosides exhibited a dependence on route of administration. Intravenous and oral administrations resulted in a greater distribution of nucleoside into axillary lymph nodes, compared with neck and mesenteric lymph nodes. Following intraperitoneal administration, however, distribution was similar in all three regions. AZT and AZdU distribute into the lymphatic system; however, AZdU accumulation was greater than that of AZT.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗