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1.
Lipids Health Dis ; 15(1): 116, 2016 Jul 12.
Article in English | MEDLINE | ID: mdl-27405296

ABSTRACT

BACKGROUND: LDL-C, non-HDL-C and ApoB levels are inter-correlated and all predict risk of atherosclerotic cardiovascular disease (ASCVD) in patients with type 2 diabetes mellitus (T2DM) and/or high TG. These levels are lowered by extended-release niacin (ERN), and changes in the ratios of these levels may affect ASCVD risk. This analysis examined the effects of extended-release niacin/laropiprant (ERN/LRPT) on the relationships between apoB:LDL-C and apoB:non-HDL-C in patients with T2DM. METHODS: T2DM patients (n = 796) had LDL-C ≥1.55 and <2.97 mmol/L and TG <5.65 mmol/L following a 4-week, lipid-modifying run-in (~78 % taking statins). ApoB:LDL-C and apoB:non-HDL-C correlations were assessed after randomized (4:3), double-blind ERN/LRPT or placebo for 12 weeks. Pearson correlation coefficients between apoB:LDL-C and apoB:non-HDL-C were computed and simple linear regression models were fitted for apoB:LDL-C and apoB:non-HDL-C at baseline and Week 12, and the correlations between measured apoB and measured vs predicted values of LDL-C and non-HDL-C were studied. RESULTS: LDL-C and especially non-HDL-C were well correlated with apoB at baseline, and treatment with ERN/LRPT increased these correlations, especially between LDL-C and apoB. Despite the tighter correlations, many patients who achieved non-HDL-C goal, and especially LDL-C goal, remained above apoB goal. There was a trend towards greater increases in these correlations in the higher TG subgroup, non-significant possibly due to the small number of subjects. CONCLUSIONS: ERN/LRPT treatment increased association of apoB with LDL-C and non-HDL-C in patients with T2DM. Lowering LDL-C, non-HDL-C and apoB with niacin has the potential to reduce coronary risk in patients with T2DM.


Subject(s)
Apolipoprotein B-100/blood , Cholesterol, LDL/blood , Delayed-Action Preparations/therapeutic use , Hyperlipidemias/drug therapy , Hypolipidemic Agents/therapeutic use , Indoles/therapeutic use , Niacin/therapeutic use , Adult , Aged , Aged, 80 and over , Blood Glucose/metabolism , Cholesterol, HDL/blood , Diabetes Mellitus, Type 2/blood , Diabetes Mellitus, Type 2/drug therapy , Diabetes Mellitus, Type 2/physiopathology , Double-Blind Method , Fasting , Female , Humans , Hyperlipidemias/blood , Hyperlipidemias/physiopathology , Hypoglycemic Agents/therapeutic use , Insulin/blood , Male , Middle Aged , Triglycerides/blood
2.
J Pediatr ; 166(6): 1377-84.e1-3, 2015 Jun.
Article in English | MEDLINE | ID: mdl-25841542

ABSTRACT

OBJECTIVES: To evaluate the lipid-altering efficacy and safety of ezetimibe monotherapy in young children with heterozygous familial hypercholesterolemia (HeFH) or nonfamilial hypercholesterolemia (nonFH). STUDY DESIGN: One hundred thirty-eight children 6-10 years of age with diagnosed HeFH or clinically important nonFH (low-density lipoprotein cholesterol [LDL-C] ≥ 160 mg/dL [4.1 mmol/L]) were enrolled into a multicenter, 12-week, randomized, double-blind, placebo-controlled study. Following screening/drug washout and a 5-week single-blind placebo-run-in with diet stabilization, subjects were randomized 2:1 to daily ezetimibe 10 mg (n = 93) or placebo (n = 45) for 12 weeks. Lipid-altering efficacy and safety were assessed in all treated patients. RESULTS: Overall, mean age was 8.3 years, 57% were girls, 80% were white, mean baseline LDL-C was 228 mg/dL (5.9 mmol/L), and 91% had HeFH. After 12 weeks, ezetimibe significantly reduced LDL-C by 27% after adjustment for placebo (P < .001) and produced significant reductions in total cholesterol (21%), nonhigh-density lipoprotein cholesterol (26%), and apolipoprotein B (20%) (P < .001 for all). LDL-C lowering response in sex, race, baseline lipids, and HeFH/nonFH subgroups was generally consistent with overall study results. Ezetimibe was well tolerated, with a safety profile similar to studies in older children, adolescents, and adults. CONCLUSIONS: Ezetimibe monotherapy produced clinically relevant reductions in LDL-C and other key lipid variables in young children with primary HeFH or clinically important nonFH, with a favorable safety/tolerability profile. TRIAL REGISTRATION: ClinicalTrials.gov: NCT00867165.


Subject(s)
Anticholesteremic Agents/therapeutic use , Azetidines/therapeutic use , Hypercholesterolemia/drug therapy , Anticholesteremic Agents/adverse effects , Azetidines/adverse effects , Child , Double-Blind Method , Ezetimibe , Female , Heterozygote , Humans , Hypercholesterolemia/genetics , Male , Single-Blind Method , Treatment Outcome
3.
Vasc Health Risk Manag ; 11: 165-72, 2015.
Article in English | MEDLINE | ID: mdl-25750540

ABSTRACT

BACKGROUND: The degree of glycemic control in patients with type 2 diabetes mellitus (T2DM) may alter lipid levels and may alter the efficacy of lipid-modifying agents. OBJECTIVE: Evaluate the lipid-modifying efficacy of extended-release niacin/laropiprant (ERN/LRPT) in subgroups of patients with T2DM with better or poorer glycemic control. METHODS: Post hoc analysis of clinical trial data from patients with T2DM who were randomized 4:3 to double-blind ERN/LRPT or placebo (n=796), examining the lipid-modifying effects of ERN/LRPT in patients with glycosylated hemoglobin or fasting plasma glucose levels above and below median baseline levels. RESULTS: At Week 12 of treatment, ERN/LRPT significantly improved low-density lipoprotein cholesterol, high-density lipoprotein cholesterol (HDL-C), non-high-density lipoprotein cholesterol, triglycerides, and lipoprotein (a), compared with placebo, with equal efficacy in patients above or below median baseline glycemic control. Compared with placebo, over 36 weeks of treatment more patients treated with ERN/LRPT had worsening of their diabetes and required intensification of antihyperglycemic medication, irrespective of baseline glycemic control. Incidences of other adverse experiences were generally low in all treatment groups. CONCLUSION: The lipid-modifying effects of ERN/LRPT are independent of the degree of baseline glycemic control in patients with T2DM (NCT00485758).


Subject(s)
Biomarkers/blood , Blood Glucose/drug effects , Diabetes Mellitus, Type 2/drug therapy , Dyslipidemias/drug therapy , Hypoglycemic Agents/therapeutic use , Hypolipidemic Agents/therapeutic use , Indoles/therapeutic use , Lipids/blood , Niacin/therapeutic use , Aged , Blood Glucose/metabolism , Delayed-Action Preparations , Diabetes Mellitus, Type 2/blood , Diabetes Mellitus, Type 2/diagnosis , Double-Blind Method , Drug Combinations , Drug Interactions , Dyslipidemias/blood , Dyslipidemias/diagnosis , Female , Glycated Hemoglobin/metabolism , Humans , Hypoglycemic Agents/adverse effects , Hypolipidemic Agents/adverse effects , Indoles/adverse effects , Male , Middle Aged , Niacin/adverse effects , Time Factors , Treatment Outcome
4.
Fundam Clin Pharmacol ; 29(2): 209-18, 2015 Apr.
Article in English | MEDLINE | ID: mdl-25431239

ABSTRACT

Co-administration of ezetimibe with atorvastatin is a generally well-tolerated treatment option that reduces LDL-C levels and improves other lipids with greater efficacy than doubling the atorvastatin dose. The objective of the study was to demonstrate the equivalent lipid-modifying efficacy of fixed-dose combination (FDC) ezetimibe/atorvastatin compared with the component agents co-administered individually in support of regulatory filing. Two randomized, 6-week, double-blind cross-over trials compared the lipid-modifying efficacy of ezetimibe/atorvastatin 10/20 mg (n = 353) or 10/40 mg (n = 280) vs. separate co-administration of ezetimibe 10 mg plus atorvastatin 20 mg (n = 346) or 40 mg (n = 280), respectively, in hypercholesterolemic patients. Percent changes from baseline in LDL-C (primary endpoint) and other lipids (secondary endpoints) were assessed by analysis of covariance; triglycerides were evaluated by longitudinal-data analysis. Expected differences between FDC and the corresponding co-administered doses were predicted from a dose-response relationship model; sample size was estimated given the expected difference and equivalence margins (±4%). LDL-C-lowering equivalence was based on 97.5% expanded confidence intervals (CI) for the difference contained within the margins; equivalence margins for other lipids were not prespecified. Ezetimibe/atorvastatin FDC 10/20 mg was equivalent to co-administered ezetimibe+atorvastatin 20 mg in reducing LDL-C levels (54.0% vs. 53.8%) as was FDC 10/40 mg and ezetimibe+atorvastatin 40 mg (58.9% vs. 58.7%), as predicted by the model. Changes in other lipids were consistent with equivalence (97.5% expanded CIs <±3%, included 0); triglyceride changes varied more. All treatments were generally well tolerated. Hypercholesterolemic patients administered ezetimibe/atorvastatin 10/20 and 10/40 mg FDC had equivalent LDL-C lowering. This FDC formulation proved to be an efficacious and generally well-tolerated lipid-lowering therapy.


Subject(s)
Anticholesteremic Agents/administration & dosage , Atorvastatin/administration & dosage , Cholesterol, LDL/antagonists & inhibitors , Ezetimibe/administration & dosage , Hypercholesterolemia/drug therapy , Aged , Cholesterol, LDL/blood , Cross-Over Studies , Dose-Response Relationship, Drug , Double-Blind Method , Drug Combinations , Drug Therapy, Combination , Female , Humans , Hypercholesterolemia/blood , Male , Middle Aged
5.
Am J Cardiol ; 112(12): 1885-95, 2013 Dec 15.
Article in English | MEDLINE | ID: mdl-24063830

ABSTRACT

Hypercholesterolemic patients (n = 1,547) at high atherosclerotic cardiovascular disease risk with low-density lipoprotein cholesterol (LDL-C) levels ≥100 and ≤160 mg/dl while treated with atorvastatin 10 mg/day entered a multicenter, randomized, double-blind, active-controlled, clinical trial using two 6-week study periods. Period I compared the efficacy/safety of (1) adding ezetimibe 10 mg (ezetimibe) to stable atorvastatin 10 mg, (2) doubling atorvastatin to 20 mg, or (3) switching to rosuvastatin 10 mg. Subjects in the latter 2 groups who persisted with elevated LDL-C levels (≥100 and ≤160 mg/dl) after period I, entered period II; subjects on atorvastatin 20 mg had ezetimibe added to their atorvastatin 20 mg, or uptitrated their atorvastatin to 40 mg; subjects on rosuvastatin 10 mg switched to atorvastatin 20 mg plus ezetimibe or uptitrated their rosuvastatin to 20 mg. Some subjects on atorvastatin 10 mg plus ezetimibe continued the same treatment into period II. At the end of period I, ezetimibe plus atorvastatin 10 mg reduced LDL-C significantly more than atorvastatin 20 mg or rosuvastatin 10 mg (22.2% vs 9.5% or 13.0%, respectively, p <0.001). At the end of period II, ezetimibe plus atorvastatin 20 mg reduced LDL-C significantly more than atorvastatin 40 mg (17.4% vs 6.9%, p <0.001); switching from rosuvastatin 10 mg to ezetimibe plus atorvastatin 20 mg reduced LDL-C significantly more than uptitrating to rosuvastatin 20 mg (17.1% vs 7.5%, p <0.001). Relative to comparative treatments, ezetimibe added to atorvastatin 10 mg (period I) or atorvastatin 20 mg (period II) produced significantly greater percent attainment of LDL-C targets <100 or <70 mg/dl, and significantly greater percent reductions in total cholesterol, non-high-density lipoprotein cholesterol, most lipid and lipoprotein ratios, and apolipoprotein B (except ezetimibe plus atorvastatin 20 vs atorvastatin 40 mg). Reports of adverse experiences were generally similar among groups. In conclusion, treatment of hypercholesterolemic subjects at high cardiovascular risk with ezetimibe added to atorvastatin 10 or 20 mg produced significantly greater improvements in key lipid parameters and significantly greater attainment of LDL-C treatment targets than doubling atorvastatin or switching to (or doubling) rosuvastatin at the compared doses.


Subject(s)
Anticholesteremic Agents/administration & dosage , Azetidines/administration & dosage , Fluorobenzenes/administration & dosage , Heptanoic Acids/administration & dosage , Hypercholesterolemia/drug therapy , Pyrimidines/administration & dosage , Pyrroles/administration & dosage , Sulfonamides/administration & dosage , Aged , Anticholesteremic Agents/therapeutic use , Atorvastatin , Azetidines/therapeutic use , Cholesterol, LDL/blood , Double-Blind Method , Drug Therapy, Combination , Ezetimibe , Female , Fluorobenzenes/therapeutic use , Heptanoic Acids/therapeutic use , Humans , Hypercholesterolemia/blood , Logistic Models , Male , Middle Aged , Pyrimidines/therapeutic use , Pyrroles/therapeutic use , Rosuvastatin Calcium , Sulfonamides/therapeutic use
6.
Lipids Health Dis ; 12: 103, 2013 Jul 16.
Article in English | MEDLINE | ID: mdl-23866306

ABSTRACT

PURPOSE: This post hoc analysis assessed switching to ezetimibe/simvastatin 10/20 mg vs doubling the baseline statin dose to simvastatin 40 mg or atorvastatin 20 mg or switching to rosuvastatin 10 mg in subgroups of obese (BMI ≥30 kg/m2) and non-obese (BMI <30 kg/m2) diabetic subjects. METHODS: This was a randomized, double-blind, 12-week study of adults 18-79 years with cardiovascular disease with low-density lipoprotein cholesterol (LDL-C) ≥70 and ≤160 mg/dl. Percent change in LDL-C and other lipids was estimated. RESULTS: In obese subjects (n = 466), percent changes in LDL-C and most other lipids were greater with ezetimibe/simvastatin vs doubling the baseline statin dose or switching to rosuvastatin. In non-obese subjects (n = 342), percent changes in LDL-C, total cholesterol, non-HDL-C, Apo B and Apo A-I were greater with ezetimibe/simvastatin vs doubling the baseline statin dose or switching to rosuvastatin; and treatment with ezetimibe/simvastatin resulted in greater changes in triglycerides vs rosuvastatin and HDL-C vs doubling the baseline statin dose. The safety profiles were generally similar. CONCLUSIONS: Regardless of baseline obesity status, switching to ezetimibe/simvastatin was more effective at reducing LDL-C, total cholesterol, non-HDL-C, and Apo B vs doubling the baseline statin dose to simvastatin 40 mg or atorvastatin 20 mg or switching to rosuvastatin 10 mg.


Subject(s)
Anticholesteremic Agents/therapeutic use , Azetidines/therapeutic use , Diabetes Mellitus, Type 1/drug therapy , Diabetes Mellitus, Type 2/drug therapy , Simvastatin/therapeutic use , Adolescent , Adult , Aged , Apolipoproteins B/blood , Atorvastatin , Cholesterol, LDL/blood , Diabetes Mellitus, Type 1/metabolism , Diabetes Mellitus, Type 2/metabolism , Ezetimibe , Female , Fluorobenzenes/therapeutic use , Heptanoic Acids/therapeutic use , Humans , Male , Middle Aged , Obesity/drug therapy , Peptide Fragments/blood , Pyrimidines/therapeutic use , Pyrroles/therapeutic use , Rosuvastatin Calcium , Sulfonamides/therapeutic use , Treatment Outcome , Young Adult
7.
Diab Vasc Dis Res ; 10(3): 277-86, 2013 May.
Article in English | MEDLINE | ID: mdl-23288881

ABSTRACT

The low-density lipoprotein cholesterol (LDL-C) lowering efficacy of switching to ezetimibe/simvastatin (EZ/S) 10/20 mg versus doubling the run-in statin dose (to simvastatin 40 mg or atorvastatin 20 mg) or switching to rosuvastatin 10 mg in subjects with cardiovascular disease (CVD) and diabetes was assessed. Endpoints included percentage change in LDL-C and percentage of patients achieving LDL-C <70 mg/dL. Significantly greater reductions in LDL-C occurred when switching to EZ/S versus statin doubling in the overall population and in subjects treated with simvastatin 20 mg or atorvastatin 10 mg (all p < 0.001). The LDL-C reduction was numerically greater when switching to EZ/S versus switching to rosuvastatin (p = 0.060). Significantly more subjects reached LDL-C <70 mg/dL with EZ/S (54.5%) versus statin doubling (27.0%) or rosuvastatin (42.5%) in the overall population (all p < 0.001) and within each stratum (all p < 0.001). Switching to EZ/S provided significantly greater reductions in LDL-C versus statin doubling and significantly greater achievement of LDL-C targets versus statin doubling or switching to rosuvastatin.


Subject(s)
Anticholesteremic Agents/therapeutic use , Azetidines/therapeutic use , Cardiovascular Diseases/prevention & control , Cholesterol, LDL/blood , Diabetes Complications/drug therapy , Diabetic Angiopathies/prevention & control , Hypercholesterolemia/drug therapy , Simvastatin/therapeutic use , Aged , Aged, 80 and over , Anticholesteremic Agents/administration & dosage , Anticholesteremic Agents/adverse effects , Atorvastatin , Azetidines/adverse effects , Cardiovascular Diseases/etiology , Diabetes Complications/blood , Diabetes Complications/physiopathology , Diabetic Angiopathies/etiology , Double-Blind Method , Drug Combinations , Drug Monitoring , Ezetimibe, Simvastatin Drug Combination , Female , Fluorobenzenes/adverse effects , Fluorobenzenes/therapeutic use , Heptanoic Acids/administration & dosage , Heptanoic Acids/adverse effects , Heptanoic Acids/therapeutic use , Humans , Hypercholesterolemia/blood , Hypercholesterolemia/complications , Hypercholesterolemia/physiopathology , Longitudinal Studies , Male , Middle Aged , Pyrimidines/adverse effects , Pyrimidines/therapeutic use , Pyrroles/administration & dosage , Pyrroles/adverse effects , Pyrroles/therapeutic use , Rosuvastatin Calcium , Severity of Illness Index , Simvastatin/administration & dosage , Simvastatin/adverse effects , Sulfonamides/adverse effects , Sulfonamides/therapeutic use
8.
Lipids Health Dis ; 11: 18, 2012 Jan 31.
Article in English | MEDLINE | ID: mdl-22293030

ABSTRACT

BACKGROUND: A considerable number of patients with severely elevated LDL-C do not achieve recommended treatment targets, despite treatment with statins. Adults at high cardiovascular risk with hypercholesterolemia and LDL-C ≥ 2.59 and ≤ 4.14 mmol/L (N = 250), pretreated with atorvastatin 20 mg were randomized to ezetimibe/simvastatin 10/40 mg or atorvastatin 40 mg for 6 weeks. The percent change in LDL-C and other lipids was assessed using a constrained longitudinal data analysis method with terms for treatment, time, time-by-treatment interaction, stratum, and time-by-stratum interaction. Percentage of subjects achieving LDL-C < 1.81 mmol/L, < 2.00 mmol/L, or < 2.59 mmol/L was assessed using a logistic regression model with terms for treatment and stratum. Tolerability was assessed. RESULTS: Switching to ezetimibe/simvastatin resulted in significantly greater changes in LDL-C (-26.81% vs.-11.81%), total cholesterol (-15.97% vs.-7.73%), non-HDL-C (-22.50% vs.-10.88%), Apo B (-17.23% vs.-9.53%), and Apo A-I (2.56% vs.-2.69%) vs. doubling the atorvastatin dose (all p ≤ 0.002), but not HDL-C, triglycerides, or hs-CRP. Significantly more subjects achieved LDL-C < 1.81 mmol/L (29% vs. 5%), < 2.00 mmol/L (38% vs. 9%) or < 2.59 mmol/L (69% vs. 41%) after switching to ezetimibe/simvastatin vs. doubling the atorvastatin dose (all p < 0.001). The overall safety profile appeared generally comparable between treatment groups. CONCLUSIONS: In high cardiovascular risk subjects with hypercholesterolemia already treated with atorvastatin 20 mg but not at LDL-C < 2.59 mmol/L, switching to combination ezetimibe/simvastatin 10/40 mg provided significantly greater LDL-C lowering and greater achievement of LDL-C targets compared with doubling the atorvastatin dose to 40 mg. Both treatments were generally well-tolerated. TRIAL REGISTRATION: Registered at clinicaltrials.gov: NCT00782184.


Subject(s)
Anticholesteremic Agents/therapeutic use , Azetidines/therapeutic use , Cardiovascular Diseases/prevention & control , Heptanoic Acids/therapeutic use , Hypercholesterolemia/drug therapy , Pyrroles/therapeutic use , Simvastatin/therapeutic use , Aged , Atorvastatin , C-Reactive Protein/metabolism , Cardiovascular Diseases/blood , Cardiovascular Diseases/etiology , Double-Blind Method , Drug Combinations , Ezetimibe , Female , Humans , Hypercholesterolemia/blood , Hypercholesterolemia/complications , Lipids/blood , Male , Middle Aged , Treatment Outcome
9.
Curr Med Res Opin ; 26(6): 1321-31, 2010 Jun.
Article in English | MEDLINE | ID: mdl-20370378

ABSTRACT

OBJECTIVE: To examine the efficacy and general safety of rivoglitazone, a novel thiazolidinedione, as a treatment for type 2 diabetes in a dose-ranging study over a period of up to 6 months. RESEARCH DESIGN AND METHODS: A 26-week, randomized, double-blind, double-dummy, placebo- and active comparator (pioglitazone 45 mg)-controlled study designed to evaluate the efficacy and safety of once-daily rivoglitazone 1, 2, or 3 mg in subjects with type 2 diabetes. The study was conducted in adults with type 2 diabetes (glycated hemoglobin [HbA(1c)] >or=7.0% and <10.5%) who were either naïve to prior antidiabetes drug treatment or discontinued pre-study antidiabetes medications and were switched to study medication. A total of 441 subjects were randomized, using an equal allocation schedule to one of five treatment arms, including placebo. The primary efficacy measurement was the change in HbA(1c) from baseline to week 26 in the intent-to-treat population (last observation carried forward), for drug treatments minus placebo (placebo-subtracted). CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov Identifier NCT00143520. RESULTS: The incidence of early discontinuations was >50%, with most cases being related to a lack of efficacy (highest on placebo) or adverse experiences (highest on rivoglitazone 3 mg). Rivoglitazone 1, 2, and 3 mg and pioglitazone 45 mg were more effective than placebo in reducing HbA(1c) from baseline to week 26 (placebo-subtracted change from baseline: -0.55% [p = 0.0034], -0.99% [p < 0.0001], -1.10% [p < 0.0001], and -0.59% [p = 0.0016], respectively). In general, all treatments were safe. The most common drug-related adverse events reported with rivoglitazone were peripheral edema and weight gain; incidences increased with dose and were higher with rivoglitazone 2 and 3 mg than with pioglitazone or rivoglitazone 1 mg. CONCLUSIONS: Rivoglitazone is a potent thiazolidinedione agent with demonstrated glycemic benefits over a 6-month period in subjects with type 2 diabetes. Once-daily doses of 1, 2, and 3 mg rivoglitazone demonstrated HbA(1c) reduction similar or superior to those observed for pioglitazone 45 mg. Limitations in generalizing from this study include a modest sample size and a high rate of discontinuation prior to the last scheduled visit.


Subject(s)
Diabetes Mellitus, Type 2/drug therapy , Hypoglycemic Agents/administration & dosage , Thiazolidinediones/administration & dosage , Adolescent , Adult , Aged , Female , Glycated Hemoglobin/analysis , Glycated Hemoglobin/drug effects , Humans , Hypoglycemic Agents/adverse effects , Hypoglycemic Agents/pharmacology , Hypoglycemic Agents/therapeutic use , Male , Middle Aged , Pioglitazone , Placebos , Thiazolidinediones/adverse effects , Thiazolidinediones/pharmacology , Treatment Outcome , Young Adult
10.
Anal Chem ; 77(18): 5800-13, 2005 Sep 15.
Article in English | MEDLINE | ID: mdl-16159109

ABSTRACT

Data mining was performed on 28 330 unique peptide tandem mass spectra for which sequences were assigned with high confidence. By dividing the spectra into different sets based on structural features and charge states of the corresponding peptides, chemical interactions involved in promoting specific cleavage patterns in gas-phase peptides were characterized. Pairwise fragmentation maps describing cleavages at all Xxx-Zzz residue combinations for b and y ions reveal that the difference in basicity between Arg and Lys results in different dissociation patterns for singly charged Arg- and Lys-ending tryptic peptides. While one dominant protonation form (proton localized) exists for Arg-ending peptides, a heterogeneous population of different protonated forms or more facile interconversion of protonated forms (proton partially mobile) exists for Lys-ending peptides. Cleavage C-terminal to acidic residues dominates spectra from singly charged peptides that have a localized proton and cleavage N-terminal to Pro dominates those that have a mobile or partially mobile proton. When Pro is absent from peptides that have a mobile or partially mobile proton, cleavage at each peptide bond becomes much more prominent. Whether the above patterns can be found in b ions, y ions, or both depends on the location of the proton holder(s) in multiply protonated peptides. Enhanced cleavages C-terminal to branched aliphatic residues (Ile, Val, Leu) are observed in both b and y ions from peptides that have a mobile proton, as well as in y ions from peptides that have a partially mobile proton; enhanced cleavages N-terminal to these residues are observed in b ions from peptides that have a partially mobile proton. Statistical tools have been designed to visualize the fragmentation maps and measure the similarity between them. The pairwise cleavage patterns observed expand our knowledge of peptide gas-phase fragmentation behaviors and may be useful in algorithm development that employs improved models to predict fragment ion intensities.


Subject(s)
Peptides/chemistry , Amino Acid Sequence , Databases, Protein , Ions/chemistry , Molecular Sequence Data , Peptides/metabolism , Static Electricity , Tandem Mass Spectrometry , Trypsin/metabolism
11.
J Am Chem Soc ; 126(10): 3034-5, 2004 Mar 17.
Article in English | MEDLINE | ID: mdl-15012117

ABSTRACT

Analysis of fragmentation patterns from 5654 unique doubly charged tryptic peptides is obtained. Great variability of average relative abundance of bond cleavage is found between different amino acid combinations. There exist similarities as well as differences between b and y ions. Strong enhancement or suppression of cleavage gives insight into possible chemical interactions at reactive conformations formed by preferred phi-psi angles.


Subject(s)
Bacterial Proteins/chemistry , Peptide Fragments/chemistry , Trypsin/chemistry , Amino Acids/chemistry , Data Display , Gases , Mass Spectrometry , Proteome/chemistry , Shewanella/chemistry , Trypsin/metabolism
12.
Am J Ther ; 2(4): 265-268, 1995 Apr.
Article in English | MEDLINE | ID: mdl-11850660

ABSTRACT

Pravastatin, an HMG CoA reductase inhibitor used in the treatment of hypercholesterolemia, is recommended for bedtime (PM) dosing. Bedtime dosing with pravastatin is slightly more efficacious but not significantly different than morning (AM) dosing in lowering LDL-C and total cholesterol. The pharmacokinetics of pravastatin and its major metabolite SQ 31,906 were determined in 20 healthy men administered a single 20-mg dose either in the morning or at bedtime in an open, randomized, crossover study. Concentrations of pravastatin and SQ 31,906 were measured in serum and urine by gas chromatograph/mass spectrometry methodology. The area under the serum concentration time curve (AUC) of pravastatin was significantly less (40%) following PM dosing compared with AM dosing. Urinary excretion of pravastatin following PM dosing was also significantly decreased. Bioavailability of SQ 31,906 was somewhat higher in the PM group (20% greater following PM administration), and urinary excretion of SQ 31,906 was significantly increased by 60% following PM dosing. The lower AUC of pravastatin following PM dosing does not diminish its efficacy, possibly because PM dosing immediately precedes the diurnal peak period of hepatic cholesterol synthesis. Lower blood levels of pravastatin following PM dosing may contribute to its favorable safety profile.

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