Steady-state pharmacokinetics of fluvastatin in healthy subjects following a new extended release fluvastatin tablet, Lescol® XL

This was an open-label, randomized, three-period, three-treatment, multiple dose, crossover study in 12 healthy male and female subjects. This study evaluated single dose and steady-state pharmacokinetics of fluvastatin following single and multiple dose administrations of a new extended release fluvastatin 8 h matrix tablet, Lescol XL 80 mg and 160 mg doses once a day. The study also included a twice a day administration of an immediate release (IR) form of fluvastatin capsule, Lescol, for comparative purposes. All doses were administered for 7 days. The safety and tolerability were also assessed. The pharmacokinetics of fluvastatin were evaluated on days 1 and 7 following each treatment. Fluvastatin systemic exposure was 50% less when administered as Lescol XL 80 mg qd compared with Lescol IR 40 mg bid. Conversely, fluvastatin systemic exposure was 22% higher when administered as Lescol XL 160 mg qd compared with Lescol IR 40 mg bid. Single doses of Lescol XL 80 mg and 160 mg were dose proportional but, deviation (30%) from dose proportionality was observed for the Lescol XL 160 mg at steady-state. There appeared to be moderate (20%-40%) accumulation of serum fluvastatin maximal concentrations and exposure after multiple doses of Lescol XL tablets. Both Lescol XL 80 mg and 160 mg showed delayed absorption and longer apparent elimination half-life compared with fluvastatin IR capsule. Single and multiple doses of fluvastatin were generally well tolerated in this healthy volunteer population. Adverse event profiles were consistent with the published safety profile of the marketed formulations. Aside from one incidence of creatine phosphokinase (CPK) elevation (following Lescol XL 160 mg qd treatment), there were no safety concerns with any of the treatments when administered acutely (7 days).

Pharmacokinetics and Lipid-Lowering Effect of Fluvastatin in Hypercholesterolaemic Patients on Maintenance Haemodialysis

Patients undergoing haemodialysis are predisposed to serum lipid abnormalities that can accelerate the development of atherosclerosis. Serum lipid levels must therefore be controlled over a long period. For patients with reduced renal function (including dialysis patients), special attention must be paid to hyperlipidaemia therapy, particularly drug selection. In this study, 30 mg/day fluvastatin was administered orally to five patients receiving maintenance haemodialysis. Their serum lipid levels and blood biochemistry were monitored during the 6 months of fluvastatin administration, and the pharmacokinetic parameters calculated. The therapeutic efficacy and safety of fluvastatin were demonstrated in this patient group. Furthermore, fluvastatin is not influenced by the dialysis membrane and does not accumulate in haemodialysis patients with hyperlipidaemia.

Levels of synthetic musk compounds in municipal wastewater for potential estimation of biota exposure in receiving waters

We analyzed water samples from the confluence of three municipal sewage treatment effluent streams, surface water, and whole carp (Cyprinus carpio) for synthetic musks for a period of 7-12 months. The lipid content of each fish was determined and compared with the concentration of musks in the whole fish tissue. Enhanced methods were used for water sampling and musk extraction. The data presented here provide insight as to the relationship between concentrations of synthetic musks in the municipal effluent and associated biota. This study confirmed the presence of polycyclic and nitro musk compounds in sewage effluent, Lake Mead water, and carp. The concentrations were found to be considerably lower than previous studies conducted in other countries. This study also provides data for polycyclic and nitro musk compounds, as well as some of the nitro musk metabolites in sewage treatment plant effluent, lake water, and carp.

DOTAP (and Other Cationic Lipids): Chemistry, Biophysics, and Transfection;

Cationic lipid-mediated nucleic acid and protein delivery is becoming increasingly popular for in vitro and in vivo applications. While the chemistry of cationic lipid carriers is moving very rapidly, and more and more sophisticated molecules are being developed, it is worthwhile to look back to understand what has been achieved in the field of cationic lipids and why in some cases delivery based on cationic lipids works and in other cases it does not. For this purpose, DOTAP is one of the best candidates; it is the most widely used cationic lipid, it is relatively cheap, and it is efficient in both in vitro and in vivo applications. The vast amount of data that have accumulated on DOTAP and related molecules could provide invaluable clues to biophysical, structural, and biological mechanisms of transfection by cationic lipids. While many issues of cationic lipid transfection still remain unclear, this review will attempt to address mainly the following issues: (1) interplay of physicochemical parameters of DOTAP formulations; (2) impact of physicochemical parameters on transfection (lipofection) efficiency by cationic reagents, in vitro and in vivo; (3) structure-activity relationships of cationic lipid formulations in cell culture and in the living organism. In addition, in vivo applications of cationic lipids are reviewed, and the problems of local versus systemic administration of lipoplexes are discussed.

Phytosterol additives increase blood pressure and promote stroke onset in salt-loaded stroke-prone spontaneously hypertensive rats

1. To assess the effect of dietary phytosterol on stroke and the lifespan of salt-loaded stroke-prone spontaneously hypertensive rats (SHRSP), we investigated the effects of the addition of phytosterol to soybean oil (phytosterol content: 0.3%) on stroke onset, lifespan following onset of stroke and overall lifespan compared with canola oil (phytosterol content: 0.9%). 2. Six-week-old male SHRSP were fed a test diet prepared by the addition of canola oil (CA diet), soybean oil (SO diet), soybean oil plus 0.6% phytosterol (SO + 0.06P diet) or soybean oil plus 4.5% phytosterol (SO + 0.45P diet) as a 10% fat source. 3. Systolic blood pressure (SBP) increased in the SO + 0.06P and SO + 0.45P groups compared with the SO group and the increase was dependent on the amount of phytosterol added, indicating that the addition of phytosterol to soybean oil may promote an increase in SBP in salt-loaded SHRSP. 4. The onset of stroke was shortest in the SO + 0.45P group and survival after the onset of stroke was shortest in the CA group. Consequently, the SO + 0.45P and CA groups showed marked lifespan shortening, indicating that a fivefold greater amount of phytosterol was required to produce an effect equivalent to that of canola oil. 5. Investigation of the mRNA expression of ATP-binding cassette (ABC) transporters involved in intestinal phytosterol absorption indicated significant decreases in the intestinal mRNA expression of Abcg5 and Abcg8 in SHRSP and Wistar-Kyoto rats compared with Wistar rats. 6. In conclusion, the addition of phytosterol to soybean oil elevated SBP and promoted the onset of stroke, which may cause a reduction in survival time. However, a fivefold greater amount of phytosterol was required to produce an effect that was equivalent to the survival time-shortening effect of canola oil. The significant decrease in the intestinal mRNA expression of Abcg5 and Abcg8 in SHRSP may be responsible, at least in part, for the unfavourable effects observed following the addition of phytosterol.

Dietary effect of different high-fat diet on rat liver stereology

BACKGROUND/AIMS

Dietary habits are considered to be responsible for a fatty liver. The aims of this work are to study the effects of different lipid sources on rat hepatic structure.

METHODS

Twenty 21-day-old to 18-month-old male rats were fed one of the following diets: soybean oil, canola oil, lard and egg yolk (LE), or canola oil+lard and egg yolk (CA+LE). The blood serum triglyceride samples were analyzed. The following hepatic biometry and the stereology parameters were determined: densities of volume (V(v)) and surface (S(v)), absolute volume (V) and surface (S) of the hepatocytes (h), fat globules (g), and hepatic sinusoids (s), and numerical density of the hepatocytes (N(v)[h]).

RESULTS

The largest values of V(v)[h], S(v)[h], V[h], and S[h] were found in the LE group. However, the largest values of V(v)[g], S(v)[g], and S[g] were found in the CA+LE group, and the smallest values of those parameters were found in the LE group. On the other hand, V[g] was larger in the CA+LE group. V(v)[s] and V[s] were larger in the LE group and smaller in the CA+ LE group.

CONCLUSION

Long-term administration of canola oil or soybean oil resulted in similar effects on hepatocytes, hepatic sinusoids, and fat globules. Long-term administration of lard and egg yolk attenuates hepatic fat accumulation and increases hepatic sinusoids. The administration of the canola oil and lard and egg yolk mixture increases hepatic fat accumulation, reducing the hepatic sinusoids.

Comparison of the retrobulbar and Peterson nerve block techniques via magnetic resonance imaging in bovine cadavers

OBJECTIVE

To use magnetic resonance (MR) imaging to describe and compare the anatomic distribution of a lipid contrast medium injected via the retrobulbar and Peterson nerve block techniques in heads of bovine cadavers.

DESIGN

Original study.

SAMPLE

5 grossly normal heads obtained from cattle at necropsy.

PROCEDURE

Standardized techniques for the modified retrobulbar and Peterson nerve blocks were established. Each cadaver had 1 treatment performed on a randomly selected side of the head; the second treatment was performed on the alternate side of the head. Injections were performed with canola oil, which is an MR-positive contrast medium. Images of heads in the transverse and dorsal planes were obtained with a 3.0 Tesla short-bore MR system.

RESULTS

The retrobulbar technique was characterized by widespread distribution of the contrast medium around the periorbital structures; further distribution of the medium was detected along the optic nerve and in the ethmoid turbinates and nasopharynx. After the Peterson nerve block technique, contrast medium was repeatedly located in the pterygopalatine fossa, but distribution to surrounding structures was minimal.

CONCLUSIONS AND CLINICAL RELEVANCE

Results indicate that the retrobulbar injection technique results in a greater distribution of contrast medium to the target nerves and surrounding structures, compared with that achieved via the Peterson nerve block technique. This may explain the previously reported clinical impression that the retrobulbar block is more reliable than the Peterson nerve block but is associated with a greater risk of complications.

Influence of CYP2C9 polymorphisms on the pharmacokinetics and cholesterol-lowering activity of (-)-3S,5R-fluvastatin and (+)-3R,5S-fluvastatin in healthy volunteers

INTRODUCTION

In vitro data indicate that biotransformation of the synthetic 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitor fluvastatin is catalyzed by the cytochrome P450 (CYP) enzyme 2C9. The consequences of CYP2C9 genetic polymorphisms on fluvastatin pharmacokinetics and on its efficacy have not been investigated in humans thus far.

METHODS

Twenty-four healthy heterozygous or homozygous carriers of the CYP2C9 variants Arg144Cys (*2) and Ile359Leu (*3) and 2 individuals with the deficient CYP2D6 genotype *4/*4 took 40 mg racemic fluvastatin daily for 14 days. All subjects had also been genotyped for CYP2C8, CYP2C19, and CYP2D6 polymorphisms. Pharmacokinetics was analyzed after the first fluvastatin administration. Serum lipid concentrations were measured before fluvastatin intake and on day 15. Plasma concentrations of (+)-3R,5S-fluvastatin and of (-)-3S,5R-fluvastatin were quantified by enantiospecific HPLC.

RESULTS

Pharmacokinetics of both enantiomers showed statistically significant differences according to the number of CYP2C9*3 alleles (P <.0001, F test). Mean (and SD) values for area under the curve of the active (+)-3R,5S-fluvastatin in carriers of the genotype CYP2C9*1/*1, *1/*3, and *3/*3 were 173 (85) micro g. L(-1). h, 231 (85) micro g. L(-1). h, and 533 (120) micro g. L(-1). h, respectively. The corresponding values for area under the curve of (-)-3S,5R-fluvastatin were 227 (133) micro g. L(-1). h, 360 (103) micro g. L(-1). h, and 1126 (311) micro g. L(-1). h for CYP2C9*1/*1, *1/*3, and *3/*3, respectively. The CYP2C9*2 variant did not have any significant influence on fluvastatin kinetics, nor did the CYP2C8*3 allele, which was tightly linked with CYP2C9*2. Total serum cholesterol and low-density lipoprotein cholesterol concentrations decreased significantly during the 14-day treatment period (P <.001), but no correlation with the CYP2C9 genotype was found.

CONCLUSIONS

The pharmacokinetics of both enantiomers of fluvastatin depended on the CYP2C9 genotype, with a 3-fold group mean difference in the active enantiomer and even greater differences in the inactive enantiomer, but differences in plasma concentrations were not reflected in cholesterol lowering after 14 days of fluvastatin intake in healthy volunteers.

Exogenous myristoylated-G(i2)alpha subunits of GTP-binding proteins are mitogens following their internalization by astrocytes in culture

Heterotrimeric GTP-binding proteins (G proteins) are involved in the coupling of a variety of cell surface receptors to different intracellular signalling pathways, some of which take part in the regulation of growth by affecting cell proliferation and/or differentiation. In cultured astrocytes, many receptors of neuropeptides and hormones are coupled to the heterotrimeric G(i) proteins which regulate the mitogen-activated protein kinase (MAPK/ERK) cascade through both the Galpha and Gbetagamma subunits. We have previously reported that functionally active recombinant myr-G(i2)alpha subunits added to such cultures are internalised and distributed within the plasma membrane and cytosol as well as in the nuclei of dividing astrocytes. Here we show that astrocytes proliferate dose-dependently in response to exogenous myr-G(i2)alpha subunits. Concentrations of 100 pM-30 nM myr-G(i2)alpha caused more than 2.5-fold increase of [3H]thymidine incorporation over basal levels. Other classes of myr-Galpha subunits, such as G(i3)alpha or G(o)alpha, induced a much lower proliferative effect. The addition of G(i1)alpha subunits to the cultures produced no change, indicating the selectivity of this effect. Even though myr-G(i2)alpha subunits are internalised by the cells regardless of their guanine nucleotide-bound state, much less [3H]thymidine incorporation was observed in the presence of GDPbetaS-myr-G(i2)alpha or GTPgammaS-myr-G(i2)alpha. Further, the fluorescent labelling was dissimilarly distributed, the signal being concentrated in the nucleus and perinuclear regions of the astrocytes. Selective disassembly of caveolae impaired both myr-G(i2)alpha internalisation and DNA induction. Together, these data reveal a proliferative effect of myr-G(i2)alpha subunits in astrocytes, and provide evidence for the incorporation of exogenous myr-G(i2)alpha subunits into the mitogen cascade activated by neurotransmitters or growth factors. The fact that Galpha proteins can enter cells is particularly interesting because options for delivering functional proteins into cells are limited. Thus, these proteins may have clinical applications for compensating deficits in the transduction mechanisms associated with several neurological diseases, or as a non-invasive membrane traversing carriers.

Acute activation of de novo sphingolipid biosynthesis upon heat shock causes an accumulation of ceramide and subsequent dephosphorylation of SR proteins

Recent studies are beginning to implicate sphingolipids in the heat stress response. In the yeast Saccharomyces cerevisiae, heat stress has been shown to activate de novo biosynthesis of sphingolipids, whereas in mammalian cells the sphingolipid ceramide has been implicated in the heat shock responses. In the current study, we found an increase in the ceramide mass of Molt-4 cells in response to heat shock, corroborating findings in HL-60 cells. Increased ceramide was determined to be from de novo biosynthesis by two major lines of evidence. First, the accumulation of ceramide was dependent upon the activities of both ceramide synthase and serine palmitoyltransferase. Second, pulse labeling studies demonstrated increased production of ceramide through the de novo biosynthetic pathway. Significantly, the de novo sphingolipid biosynthetic pathway was acutely induced upon heat shock, which resulted in a 2-fold increased flux in newly made ceramides within 1-2 min of exposure to 42.5 degrees C. Functionally, heat shock induced the dephosphorylation of the SR proteins, and this effect was demonstrated to be dependent upon the accumulation of de novo-produced ceramides. Thus, these studies disclose an evolutionary conserved activation of the de novo pathway in response to heat shock. Moreover, SR dephosphorylation is emerging as a specific downstream target of accumulation of newly made ceramides in mammalian cells.

Effects of SREBF-1a and SCAP polymorphisms on plasma levels of lipids, severity, progression and regression of coronary atherosclerosis and response to therapy with fluvastatin

Sterol regulatory elements binding factor-1a (SREBF-1a) and SREBF cleavage activating protein (SCAP) regulate lipids homeostasis. Polymorphisms in SREBF-1a and SCAP could affect plasma levels of lipids and risk of atherosclerosis. We determined association of SREBF-1a -36del/G and SCAP 2386A/G genotypes with plasma levels of lipids, severity and progression/regression of coronary atherosclerosis, and response to treatment with fluvastatin in a well-characterized Lipoprotein Coronary Atherosclerosis Study population. Plasma lipids and quantitative indices of coronary atherosclerosis were obtained at baseline and 2.5 years following randomization to fluvastatin or placebo in 372 subjects. Fluvastatin reduced plasma levels of total cholesterol by 16%, LDL-C by 25%, and ApoB by 16% and increased plasma levels of HDL-C by 9% and apoA-1 by 7%. Distributions of SREBF-1a SCAP genotypes were 60 GG, 172 del-G and 140 del-del and 88 GG, 188 GA and 96 AA, respectively. There were no significant differences in baseline plasma levels of lipids or indices of severity of atherosclerosis among the genotypes of each gene. There was a strong graded genotype-treatment interaction between SREBF-1a genotypes and change in apoA-I levels in response to fluvastatin (16.5% increase in GG, 10.5% in del/G, and 0.4% in del/del groups). Modest interactions between SREBF-1a genotypes and changes in HDL-C, and apoC-III levels in response to fluvastatin were also present. No genotype-treatment interaction for progression or regression of coronary atherosclerosis was detected. There were no significant interactions between SCAP genotypes and response to therapy. Thus we detected a strong graded interaction between SREBF-1a -36del/G genotypes and response of plasma apoA-I to treatment with fluvastatin.

Pharmacokinetics of fluvastatin in subjects with renal impairment and nephrotic syndrome

The pharmacokinetics (PK) and safety of fluvastatin, a hydroxymethylglutaryl-coenzyme A reductase inhibitor, were assessed in subjects with renal impairment and nephrotic syndrome. In a single-center, open-label, parallel-group study, a single dose of fluvastatin 40 mg was administered to subjects (8 per group, n = 48) with nephrotic syndrome (group II), healthy subjects (group I), and subjects with various degrees of renal impairment (groups III to VI). Subjects undergoing hemodialysis received two doses, one 2 days before and one just prior to hemodialysis. Blood samples to determine the PK parameters of fluvastatin were collected from 0 to 12 hours after drug intake. Noncompartmental PK evaluation and statistical analysis (descriptive and ANOVA) were performed. Safety was evaluated and vital signs were monitored. There was no difference in the PK parameters AUC0-infinity and Cmax of fluvastatin between healthy subjects and subjects with renal impairment. Fluvastatin was not removed from plasma by hemodialysis. In patients with nephrotic syndrome, the values for AUC0-infinity and Cmax were less than half of those obtained in the other groups; terminal half-life values, however, were comparable. Fluvastatin was well tolerated in all study participants. Only few adverse events of mild to moderate intensity were reported. There were no clinically relevant changes in laboratory parameters in the subjects with renal impairment. Renal impairment did not affect the PK of fluvastatin after a single oral dose. Exposure to fluvastatin was lower in subjects with nephrotic syndrome. Fluvastatin also was well tolerated in subjects with nephrotic syndrome.

Chemical hydrolysis of DOTAP and DOPE in a liposomal environment

In this study the hydrolysis kinetics of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE) and 1,2-dioleoyltrimethylammoniumpropane (DOTAP) in net neutral DPPC-DOPE (3:1, mol/mol) and cationic DOTAP-DOPE (1:1, mol/mol) liposomes are described. The log k(obs)-pH profile for DOTAP-DOPE liposomes differs markedly from earlier observed hydrolysis profiles: the slope approaches zero in the acidic region and +1 in the alkaline region. The concept of amine-influenced hydrolysis is introduced to explain the lack of pH dependency in the acidic region of the log k(obs)-pH profiles.

Proteolipidic vectors for gene transfer to the lung

In order to develop improved synthetic gene transfer vectors, we have synthesized bifunctional peptides composed of a DNA binding peptide (P2) and ligand peptides selected by the phage display technique on tracheal epithelial cells. We have evaluated the capacity of these peptides to enhance the gene transfer efficiency of the cationic lipid DOTAP to the mouse lung. To optimize the in vivo transfection efficiency, we first compared the efficiency of DOTAP to transfect the lung by either intravenous injection or aerosolization. We then tested DNA/Peptide/DOTAP complexes formed at different Peptide/DNA and DOTAP/DNA charge ratios. Under optimal conditions, precompaction of DNA by peptide P2 gave a higher expression in the mouse lung using the luciferase reporter gene than DOTAP/DNA complexes. A further increase of transfection efficiency was obtained with the bifunctional peptide P2-9. Experiments performed with the GFP reporter gene showed expression in the alveolar parenchyme.

Intestinal absorption and lymphatic transport of a high gamma-linolenic acid canola oil in lymph fistula Sprague-Dawley rats

A new canola strain capable of producing >30% gamma-linolenic acid [GLA, 18:3(n-6)] in the seed oil has been developed in our laboratories. This study compares the intestinal absorption and lymphatic transport of this newly developed high GLA content canola oil (HGCO) with traditional GLA-rich borage oil (BO) using a lymph fistula rat model. To assess the extent that 1 mL of GLA in the supplemented oil was absorbed and transported, the fatty acid compositions of triglycerides in mesenteric lymph were compared over a 24-h collection period. The digestion, uptake and lymphatic transport of HGCO and the normal physiologic changes associated with fat absorption (e.g., lymph flow and an increase in lymphatic endogenous lipids outputs, triglycerides, cholesterol and phospholipids) were similar in the HGCO-and the BO-fed rats. The original differences in gamma-linolenic acid content in HGCO and BO were preserved in the fatty acid composition of the rats' lymph lipid. We conclude that the HGCO derived from the genetically modified canola plant is absorbed and transported into lymph similarly to BO.

Nonviral vector for efficient gene transfer to human ovarian adenocarcinoma cells

OBJECTIVE

Various strategies have been attempted to design efficient protocols for ovarian cancer gene therapy but there has been little progress in their clinical application. In this study, we formulated and evaluated a new cationic liposome prepared with dioleoyltrimethylaminopropane (DOTAP), 1,2-dioleoyl-3-phosphophatidylethanolamine (DOPE), and cholesterol (Chol) (DDC) for plasmid DNA transfer into ovarian cancer cells.

METHOD

The DDC liposome was prepared by mixing the DOTAP:DOPE:Cholin a 1:0.7:0.3 molar ratio using the extrusion method. Plasmid DNA (pEGFP-C1) and DDC were complexed at various weight ratios to find the optimum condition and the percentage of transfected cells was determined by selecting a green fluorescence protein (GFP) expressing cells in flow cytometry. The transfection efficiency of the DDC liposome was compared with 3[N-(N,N-dimethylaminoethylene) carbamoyl] cholesterol (DC-Chol)/DOPE liposome and commercially available lifopectin.

RESULTS

The optimal transfection of plasmid DNA was achieved at a 1:4 (w/w) ratio of DDC to DNA. The DDC/DNA complex exhibited higher transfection efficiency in human ovarian cancer cells (OVCAR-3 and SK-OV-3 cells) compared to that in other types of cell lines (NCI-NIH:522 and HepG2 cells). Flow cytometric analysis revealed that the DDC/DNA complex exhibited an over fourfold increase in GFP expression levels compared with DC-Chol/DOPE or lipofectin in OVCAR-3 cells. This result was further confirmed by confocal microscopy and RT-PCR analysis.

CONCLUSION

These results suggest that our newly formulated cationic liposome (DDC) appears to be a promising nonviral vector for treating ovarian adenocarcinoma because of its selective high gene transfer ability in ovarian cancer cells.

Stereoselective analysis of fluvastatin in human plasma for pharmacokinetic studies

Fluvastatin, an inhibitor of cholesterol biosynthesis, is commercialized as a racemic mixture of the (+)-3R,5S and (-)-3S,5R stereoisomers, although inhibition of HMG-CoA reductase mainly resides in the (+)-(3R,5S)-fluvastatin isomer. The aim of the present study was to analyze fluvastatin isomers in human plasma with application to studies on kinetic disposition. Plasma samples of 1 ml were eluted into 3 ml LC-18 Supelclean (Supelco) columns equilibrated with methanol and water. The columns were washed with water and acetonitrile and then eluted with methanol containing 0.2% diethylamine. The (+)-3R,5S and (-)-3S,5R isomers were separated by HPLC on a Chiralcel OD-H chiral phase column and detected by fluorescence (lambda(ex) 305 nm; lambda(em) 390 nm). The quantification limit was 0.75 ng for each isomer/ml plasma and linearity was observed up to 625 ng/ml. The relative standard deviations obtained for intra- and inter-assay precision were lower than 10% and the recovery was higher than 80% for both enantiomers. Application of the method to a stereoselective study on the pharmacokinetics of fluvastatin administered as a single oral dose (Lescol, 20 mg) to a healthy volunteer revealed stereoselectivity, with the highest plasma concentrations being observed for the (-)-3S,5R isomer (Cmax 92.4 vs. 60.3 ng/ml, AUC(0-infinity) 133.3 vs. 97.4 ng h/ml, Cl/f 150.2 vs. 205.2 l h(-1) and Vd/f 4.4 vs. 6.0 l/kg).

Pharmacokinetics and pharmacodynamics of fluvastatin in heart transplant recipients taking cyclosporine A

During the last decades, transplantation has become an established tool for the treatment of terminal organ failure. Beside immunological factors, hyperlipidemia is the main problem after heart transplantation, causing rapid transplant coronary artery disease (TxCAD) and poor long-term prognosis at the beginning of the transplantation. Heart transplant recipients are now effectively treated with lipid lowering substances, of which HMG-CoA-reductase inhibitors are the most potent. However, treatment with these substances correlates with an increased risk for the development of rhabdomyolysis due to therapy with the immunosuppressive cyclosporine A. Our study monitored the safety and efficacy of treatment with the HMG-CoA reductase inhibitor fluvastatin in heart transplant recipients compared to healthy controls. We investigated 10 patients receiving immunosuppressive therapy consisting of cyclosporine A, prednisone, and azathioprine who had increased concentrations of LDL-cholesterol (LDL-C), and 10 age-matched healthy controls. The patients were treated with 40 mg/day fluvastatin for 4 weeks and 20 mg/day for 4 additional weeks. Control individuals received 40 mg/day fluvastatin for 4 weeks only. Parameters of fluvastatin pharmacokinetics (maximum concentration of the drug (C(max.)), time (t(max.)) to reach C(max.), area under the concentration vs. time curve (AUC(0h-24h)), elimination half-life time (t(1/2))), apparent total body clearance (CL), blood cyclosporine A concentration, plasma lipids, and safety parameters were determined in both study groups at the beginning of the study and after 4 weeks. The latter were determined in the patient group also after 8 and 12 weeks. Treatment with 40 mg/day fluvastatin caused a significant decrease in total cholesterol (patients: 5.47 +/- 1.32 mmol/L vs. 7.30 +/- 1.83 mmol/L; controls: 4.69 +/- 0.64 mmol/L vs. 5.81 +/- 0.72 mmol/L), LDL-C (patients: 3.28 +/- 1.25 mmol/L vs. 5.00 +/- 1.85 mmol/L; controls: 2.58 +/- 0.63 mmol/L vs. 3.50 +/- 0.70 mmol/L), and triglycerides (patients: 1.99 +/- 0.77 mmol/L vs. 2.50 +/- 1.00 mmol/L; controls: 1.24 +/- 0.46 mmol/L vs. 1.72 +/- 0.67 mmol/L) in both study groups, whereas HDL-C was not significantly changed (patients: 1.29 +/- 0.35 mmol/L vs. 1.17 +/- 0.32 mmol/L; controls: 1.55 +/- 0.30 mmol/L vs. 1.53 +/- 0.26 mmol/L). Values of C(max.) and AUC(0h-24h) were higher in the patient group than in the control group (day 1, patients vs. controls, C(max.): 869.4 +/- 604.0 ng/mL vs. 211.9 +/- 113.9 ng/mL; AUC(0h-24h): 1948.8 +/- 1347.9 ng/mL*h vs. 549.4 +/- 247.4 ng/mL*h), whereas the corresponding value of CL was lower in the patient group (33.3 +/- 24.5 L/h vs. 107.9 +/- 95.8 L/h), and the values of t(max.) and t(1/2) showed no differences. In addition, values of C(max.) and AUC(0h-24h) after administration of 40 mg/day fluvastatin for 4 weeks in both groups were slightly higher than at the beginning, whereas the value of CL was slightly lower (day 28, patients vs. controls, C(max.): 1530.4 +/- 960.4 ng/mL vs. 254.7 +/- 199.8 ng/mL; AUC(0h-24h): 2615.3 +/- 1379.4 ng/mL*h vs. 841.8 +/- 421.4 ng/mL*h; CL: day 28, 21.4 +/- 15.3 L/h vs. 61.5 +/- 36.6 L/h). Except for an intermittent increase of creatine kinase, safety parameters showed no increases within the observation period. Our data suggest that fluvastatin effectively lowers plasma concentrations of cholesterol and LDL-C in patients after heart transplantation, however, the metabolism of fluvastatin is affected by concomitant therapy with cyclosporine A. Serum concentrations of fluvastatin should be monitored in cases of concomitant therapy with other substances interfering in the metabolism by competing cytochrome enzymes.

Clinical pharmacokinetics of fluvastatin

Fluvastatin, the first fully synthetic HMG-CoA reductase inhibitor, has been shown to reduce cholesterol in patients with hyperlipidaemia, to prevent subsequent coronary events in patients with established coronary heart disease, and to alter endothelial function and plaque stability in animal models. Fluvastatin is relatively hydrophilic, compared with the semisynthetic HMG-CoA reductase inhibitors, and, therefore, it is extensively absorbed from the gastrointestinal tract. After absorption, it is nearly completely extracted and metabolised in the liver to 2 hydroxylated metabolites and an N-desisopropyl metabolite, which are excreted in the bile. Approximately 95% of a dose is recovered in the faeces, with 60% of a dose recovered as the 3 metabolites. The 6-hydroxy and N-desisopropyl fluvastatin metabolites are exclusively generated by cytochrome P450 (CYP) 2C9 and do not accumulate in the blood. CYP2C9, CYP3A4, CYP2C8 and CYP2D6 form the 5-hydroxy fluvastatin metabolite. Because of its hydrophilic nature and extensive plasma protein binding, fluvastatin has a small volume of distribution with minimal concentrations in extrahepatic tissues. The pharmacokinetics of fluvastatin are not influenced by renal function, due to its extensive metabolism and biliary excretion; limited data in patients with cirrhosis suggest a 30% reduction in oral clearance. Age and gender do not appear to affect the disposition of fluvastatin. CYP3A4 inhibitors (erythromycin, ketoconazole and itraconazole) have no effect on fluvastatin pharmacokinetics, in contrast to other HMG-CoA reductase inhibitors which are primarily metabolised by CYP3A and are subject to potential drug interactions with CYP3A inhibitors. Coadministration of fluvastatin with gastrointestinal agents such as cholestyramine, and gastric acid regulating agents (H2 receptor antagonists and proton pump inhibitors), significantly alters fluvastatin disposition by decreasing and increasing bioavailability, respectively. The nonspecific CYP inducer rifampicin (rifampin) significantly increases fluvastatin oral clearance. In addition to being a CYP2C9 substrate, fluvastatin demonstrates inhibitory effects on this isoenzyme in vitro and in vivo. In human liver microsomes, fluvastatin significantly inhibits the hydroxylation of 2 CYP2C9 substrates, tolbutamide and diclofenac. The oral clearances of the CYP2C9 substrates diclofenac, tolbutamide, glibenclamide (glyburide) and losartan are reduced by 15 to 25% when coadministered with fluvastatin. These alterations have not been shown to be clinically significant. There are inadequate data evaluating the potential interaction of fluvastatin with warfarin and phenytoin, 2 CYP2C9 substrates with a narrow therapeutic index, and caution is recommended when using fluvastatin with these agents. Fluvastatin does not appear to have a significant effect on other CYP isoenzymes or P-glycoprotein-mediated transport in vivo.

Metabolism and drug interactions of 3-hydroxy-3-methylglutaryl coenzyme A-reductase inhibitors (statins)

3-Hydroxy-3-methylglutaryl coenzyme A (HMG-CoA)-reductase inhibitors (statins) are mainly considered for long-term use and often constitute part of a multiple-drug regime. Besides common adverse drug effects, such as nausea, abdominal discomfort and headaches, all statins harbour the risk of myopathy and fatal rhabdomyolysis. Usually, the frequency of myopathy is low but the incidence increases during concomitant drug therapy. Statins do not differ in their pharmacodynamic property. Therefore, the differences in their pharmacokinetic profiles, i.e. affinity for metabolising enzymes, constitute the rationale for choosing a specific statin especially for combination therapy. In order to point out harmful combinations of therapeutics, this review summarises the pharmacokinetic data of six clinically used statins (atorvastatin, cerivastatin, fluvastatin, lovastatin, pravastatin and simvastatin) with special regard to metabolism and drug interactions. In summary, statins that lack a significant hepatic metabolism, i.e. pravastatin, or that are metabolised by more than one cytochrome P450 isoenzyme, i.e. fluvastatin, or whose metabolism is taken over by other cytochrome P450 isoenzymes in case of blockage of the main metabolising enzyme, i.e. cerivastatin, are the least prone to drug interactions. Nevertheless, in case of a specific concomitant drug therapy known to be associated with a higher risk of adverse events, i.e. cyclosporin A and statin, clinical symptoms of myopathy and biochemical data, such as increasing serum creatine phosphokinase, should be monitored carefully.

Safety, tolerability, and pharmacokinetics of an extended-release formulation of fluvastatin administered once daily to patients with primary hypercholesterolemia

Fluvastatin sodium (Lescol, Novartis Pharmaceutical Corp., East Hanover, NJ, U.S.A.), a potent 3-hydroxy-3-methylglutaryl coenzyme A (HMG Co-A) reductase inhibitor that limits cholesterol biosynthesis, is available as a 40-mg immediate-release formulation capsule. An extended-release formulation for once-daily administration has been developed for patients with primary hypercholesterolemia who may benefit from doses higher than 40 mg/day. This phase I study evaluated the safety, tolerability, and pharmacokinetics of a new fluvastatin extended-release formulation at doses ranging from 80-640 mg/day in 40 hypercholesterolemic patients. After a 2-week dietary stabilization phase, patients (Fredrickson type IIa/IIb), 18-55 years of age, were randomly assigned to four groups to receive oral fluvastatin extended-release (80, 160, 320, or 640 mg) or matching placebo once daily for 13 days. Fluvastatin extended-release was generally safe and well tolerated at doses of 80-320 mg/day. Within this dose range, linear pharmacokinetics was observed after single and multiple dosing. At 640 mg, fluvastatin extended-release was not well tolerated. Six of the seven actively treated patients at this dose experienced adverse events, including diarrhea, headache, and clinically relevant elevations in serum transaminase concentrations. In addition, nonlinear pharmacokinetics, possibly due to saturation of first-pass metabolism, was observed at this dose, causing higher than expected serum drug concentrations. Once-daily administration of fluvastatin extended-release at doses of 80-320 mg/day was generally safe and well tolerated in patients with primary hypercholesterolemia over a 13-day dosing period.

Dose dependency of fluvastatin pharmacokinetics in serum determined by reversed phase HPLC

BACKGROUND

Fluvastatin is an inhibitor of the 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, effectively lowering serum cholesterol concentrations. A high-performance liquid chromatography (HPLC) assay was developed that determined the pharmacokinetics of fluvastatin in healthy individuals after administration of 40 and 80 mg fluvastatin.

METHODS

The method was linear for serum concentrations between 10 ng/mL and 5,000 ng/mL, showing good coefficients of variations and sample stability. After administration of 40 mg fluvastatin, the mean values of the area under the serum concentration vs time curve (AUC), the maximum serum drug concentration (C(max)), the time to reach C(max) (t(max)), and the serum elimination half-life time were 528.5 +/-358.8 ng/mL x h, 149.6 +/-56.0 ng/mL, 60.0 +/-30.0 minutes, and 108.0 +/-67.9 minutes, respectively. The corresponding values for a dose of 80 mg fluvastatin were 1417.7 +/-879.2 ng/mL x h, 1024.7 +/-1085.1 ng/mL, 60.0 +/-21.2 minutes, and 106.0 +/-73.6 minutes, respectively. Doubling of the dose from 40 mg to 80 mg caused an overproportional increase of AUC and C(max).

RESULTS AND CONCLUSION

Results suggest that the measurement of fluvastatin serum concentrations by means of HPLC provides reliable data within the broad range of physiological serum concentrations. The pharmacokinetic data after administration of high doses (80 mg) showed an overproportional increase of AUC and C(max), suggesting a saturation of the hepatic first-pass effect. Thus, in patients treated with additional substances interfering with fluvastatin metabolism, fluvastatin serum concentrations should be analyzed.

Species differences in beta-oxidative metabolism of a thromboxane A2-receptor antagonist [(+)-S-145] in rat, dog and monkey

1. The formation of beta-oxidized metabolites from (+)-S-145 [(+)-(Z)-7-[(1R, 2S, 3S, 4S)-3-(benzenesulphonamide)bicyclo-[2.2.]-hept-2-yl]-5-heptenoic acid] by liver homogenates were compared between rat, dog and monkey. Species differences were found in hepatic beta-oxidation capacities. The results agree with the qualitative and quantitative differences in beta-oxidized metabolite proportions among these species observed in vivo. 2. The activities of microsomal (+)-S-145-CoA synthesis, the initial step of the beta-oxidation, were determined. Species differences in their intrinsic clearances primarily agreed with those of the beta-oxidized metabolite formation. 3. (+)-S-145-CoA oxidation activities towards (+)-S-145-CoA by liver homogenates were much higher than the beta-oxidized metabolite formation in all species, indicating that formed (+)-S-145-CoA was immediately beta-oxidized in peroxisomes. The species differences were inconsistent with those of beta-oxidized metabolite formation in vitro. 4. Therefore, quantitative differences of hepatic (+)-S-145 beta-oxidation capacity in rat, dog and monkey were considered to be mainly due to the species difference in (+)-S-145-CoA formation.

Efficacy and tolerability of fluvastatin extended-release delivery system: a pooled analysis

BACKGROUND

At high doses, the pharmacokinetics of fluvastatin immediate-release (IR) are nonlinear, possibly due to saturation of hepatic uptake. Fluvastatin delivery to the liver in a slower but sustained fashion would be expected to avoid hepatic saturation without elevating systemic drug levels.

OBJECTIVE

This pooled analysis compared the efficacy and tolerability of extended-release (XL) 80-mg and IR 40-mg formulations of fluvastatin in lowering low-density lipoprotein cholesterol (LDL-C) and triglyceride (TG) levels and raising high-density lipoprotein cholesterol (HDL-C) levels in patients with hypercholesterolemia.

METHODS

Data were pooled from 3 double-blind, randomized, active-controlled, multicenter, parallel-group studies that compared changes in lipid and apolipoprotein levels with fluvastatin XL 80 mg at bedtime (HS) with changes in fluvastatin IR 40 mg HS or BID in patients aged > or =18 years with primary hypercholesterolemia (consistently elevated LDL-C level [> or =160 mg/dL] and plasma TG levels < or =400 mg/dL). The primary efficacy variable was percent change in LDL-C from baseline.

RESULTS

The pooled analysis provided an intent-to-treat efficacy study population of 1674 patients. At 4 weeks, fluvastatin XL 80 mg HS reduced LDL-C levels by a mean of 36.3% (median 38%), significantly greater than a mean reduction of 25.9% (median 27%) seen with fluvastatin IR 40 mg HS, and an incremental additional mean reduction in LDL-C of 10.4% (P < 0.001). At 4 and 24 weeks, fluvastatin XL 80 mg HS provided an LDL-C reduction equivalent to fluvastatin IR 40 mg BID (P < 0.001 for noninferiority). Significant, dose-related changes in HDL-C, LDL-C:HDL-C ratio, total cholesterol, TG, and apolipoprotein A-I and apolipoprotein B levels also occurred. Mean HDL-C level increased by 8.7% and median TG level decreased by 19% with fluvastatin XL 80 mg HS (P < 0.001 and P < 0.05 vs fluvastatin IR 40 mg HS, respectively). Maximum mean increases in HDL-C level (21%) and median decreases in TG level (31%) with fluvastatin XL 80 mg HS occurred in patients with type IIb dyslipidemia and the highest baseline TG. Adverse events were mild, with similar frequency in all treatment groups.

CONCLUSIONS

Once-daily administration of fluvastatin XL 80 mg provides enhanced efficacy with an additional 10.4% reduction in LDL-C levels compared with fluvastatin IR 40 mg HS, and superior increases in HDL-C levels, particularly in patients with elevated TG levels (P < 0.05 vs fluvastatin IR 40 mg HS). Fluvastatin XL 80 mg HS has a good tolerability profile and is effective as starting and maintenance lipid-lowering treatment in patients with type II hypercholesterolemia.