Effects of Single Dose Rifampin on the Pharmacokinetics of Fluvastatin in Healthy Volunteers.

The objective of this study was to determine the effects of the OATP inhibitor rifampin on pharmacokinetic of Biopharmaceutics Drug Disposition Classification System Class 1 compound fluvastatin. A crossover study was carried out in 10 healthy subjects who were randomized to 2 phases to receive fluvastatin 20 mg orally alone and following a 30-minute 600 mg i.v. infusion of rifampin. The results demonstrated that i.v. rifampin increased the mean area under the plasma fluvastatin concentration-time curve (AUC0-∞ ) by 255%, mean peak plasma concentration (Cmax ) by 254%, decreased oral volume of distribution by 71%, whereas the mean elimination terminal half-life (T1/2 ), mean absorption time (MAT), and time to peak concentration (Tpeak ) of fluvastatin did not significantly change. The study demonstrated that rifampin exhibited a significant drug interaction with fluvastatin. The mechanism of the increased plasma concentrations is likely due to inhibition of OATP transporters in hepatocytes.

Food, Acid Supplementation and Drug Absorption - a Complicated Gastric Mix: a Randomized Control Trial.

PURPOSE: The purpose of this study was to determine the impact of food on gastric pH and the ability of over the counter betaine hydrochloride (BHCl) acid to reacidify gastric pH after food-induced elevations in gastric pH. METHODS: This open-label cross over clinical study (NCT02758015) included 9 subjects who were randomly assigned to one of 16 possible, 4-period cross-over sequences to determine the impact and relationship of food and gastric pH with acid supplementation. Subjects were administered various doses (1500 mg, 3000 mg and 4500 mg) of betaine hydrochloride (BHCl) to determine the ability of acid supplementation to reacidify gastric pH after the elevation of gastric pH caused by the ingestion of food. RESULTS: Following the administration of food and the resulting elevation in gastric pH, time to return to baseline gastric pH levels without acid supplementation was 49.7 ± 14.0 min. Administering 4500 mg of BHCl acid in capsules was able to reacidify gastric pH levels back to baseline following the administration of food in approximately 17.3 ± 5.9 min. AUCpH of each treatment were similar and not statistically different. Mean max pH following the administration of food was 3.20 ± 0.55. CONCLUSION: The ability of food to elevate and maintain gastric pH levels in the presence of acid supplementation was made evident throughout the study. A 4500 mg dose of BHCl was required to reacidify gastric pH after the administration of food. This study details the difficulty faced by clinicians in dosing a poorly soluble, weakly basic drug to patients receiving acid reducing agents where administration with food is recommended to avoid gastric side effects. TRIAL REGISTRATION: https://clinicaltrials.gov/ct2/show/NCT02758015.

11C-L-methyl methionine dynamic PET/CT of skeletal muscle: response to protein supplementation compared to L-[ring 13C6] phenylalanine infusion with serial muscle biopsy.

OBJECTIVE: The objective of this study was to determine if clinical dynamic PET/CT imaging with 11C-L-methyl-methionine (11C-MET) in healthy older women can provide an estimate of tissue-level post-absorptive and post-prandial skeletal muscle protein synthesis that is consistent with the more traditional method of calculating fractional synthesis rate (FSR) of muscle protein synthesis from skeletal muscle biopsies obtained during an infusion of L-[ring 13C6] phenylalanine (13C6-Phe). METHODS: Healthy older women (73 ± 5 years) completed both dynamic PET/CT imaging with 11C-MET and a stable isotope infusion of 13C6-Phe with biopsies to measure the skeletal muscle protein synthetic response to 25 g of a whey protein supplement. Graphical estimation of the Patlak coefficient Ki from analysis of the dynamic PET/CT images was employed as a measure of incorporation of 11 C-MET in the mid-thigh muscle bundle. RESULTS: Post-prandial values [mean ± standard error of the mean (SEM)] were higher than post-absorptive values for both Ki (0.0095 ± 0.001 vs. 0.00785 ± 0.001 min-1, p < 0.05) and FSR (0.083 ± 0.008 vs. 0.049 ± 0.006%/h, p < 0.001) in response to the whey protein supplement. The percent increase in Ki and FSR in response to the whey protein supplement was significantly correlated (r = 0.79, p = 0.015). CONCLUSIONS: Dynamic PET/CT imaging with 11C-MET provides an estimate of the post-prandial anabolic response that is consistent with a traditional, invasive stable isotope, and muscle biopsy approach. These results support the potential future use of 11C-MET imaging as a non-invasive method for assessing conditions affecting skeletal muscle protein synthesis.

Meal Effects Confound Attempts to Counteract Rabeprazole-Induced Hypochlorhydria Decreases in Atazanavir Absorption.

PURPOSE: Clinically relevant pharmacokinetic interactions exist between gastric acid-reducing agents and certain weakly basic drugs that rely on acidic environments for optimal oral absorption. In this study, we examine whether the administration of betaine hydrochloride under fed conditions can enhance the absorption of atazanavir, an HIV-1 protease inhibitor, during pharmacologically-induced hypochlorhydria. METHODS: In this randomized, single-dose, 3 period, crossover study healthy volunteers received ritonavir-boosted atazanavir (atazanavir/ritonavir 300/100 mg) alone, following pretreatment with the proton pump inhibitor rabeprazole (20 mg twice daily), and with 1500 mg of betaine HCl after rabeprazole pretreatment. Atazanavir was administered with a light meal and gastric pH was monitored using the Heidelberg Capsule. RESULTS: Pretreatment with rabeprazole resulted in significant reductions in atazanavir Cmax (p < 0.01) and AUC0-last (p < 0.001) (71 and 70%, respectively), and modest decreases in ritonavir Cmax and AUClast (p < 0.01) (40% and 41%, respectively). The addition of betaine HCl restored 13% of ATV Cmax and 12% of AUClast lost due to rabeprazole. CONCLUSIONS: The co-administration of rabeprazole with atazanavir resulted in significant decreases in atazanavir exposure. The addition of betaine HCl did not sufficiently mitigate the loss of ATV exposure observed during RAB-induced hypochlorhydria. Meal effects lead to a marked difference in the outcome of betaine HCl on atazanavir exposure than we previously reported for dasatanib under fasting conditions.

The use of betaine HCl to enhance dasatinib absorption in healthy volunteers with rabeprazole-induced hypochlorhydria.

Many orally administered, small-molecule, targeted anticancer drugs, such as dasatinib, exhibit pH-dependent solubility and reduced drug exposure when given with acid-reducing agents. We previously demonstrated that betaine hydrochloride (BHCl) can transiently re-acidify gastric pH in healthy volunteers with drug-induced hypochlorhydria. In this randomized, single-dose, three-way crossover study, healthy volunteers received dasatinib (100 mg) alone, after pretreatment with rabeprazole, and with 1500 mg BHCl after rabeprazole pretreatment, to determine if BHCl can enhance dasatinib absorption in hypochlorhydric conditions. Rabeprazole (20 mg b.i.d.) significantly reduced dasatinib Cmax and AUC0-∞ by 92 and 78%, respectively. However, coadministration of BHCl significantly increased dasatinib Cmax and AUC0-∞ by 15- and 6.7-fold, restoring them to 105 and 121%, respectively, of the control (dasatinib alone). Therefore, BHCl reversed the impact of hypochlorhydria on dasatinib drug exposure and may be an effective strategy to mitigate potential drug-drug interactions for drugs that exhibit pH-dependent solubility and are administered orally under hypochlorhydric conditions.

Gastric reacidification with betaine HCl in healthy volunteers with rabeprazole-induced hypochlorhydria.

Previous studies have demonstrated that increased gastric pH from the use of acid-reducing agents, such as proton-pump inhibitors or H2-receptor antagonists, can significantly impact the absorption of weakly basic drugs that exhibit pH-dependent solubility. Clinically practical strategies to mitigate this interaction have not been developed. This pilot study evaluated the extent and time course of gastric reacidification after a solid oral dosage form of anhydrous betaine HCl in healthy volunteers with pharmacologically induced hypochlorhydria. Six healthy volunteers with baseline normochlorhydria (fasting gastric pH < 4) were enrolled in this single period study. Hypochlorhydria was induced via 20 mg oral rabeprazole twice daily for four days. On the fifth day, an additional 20 mg dose of oral rabeprazole was given and gastric pH was monitored continuously using the Heidelberg pH capsule. After gastric pH > 4 was confirmed for 15 min, 1500 mg of betaine HCl was given orally with 90 mL of water and gastric pH was continuously monitored for 2 h. Betaine HCl significantly lowered gastric pH by 4.5 (± 0.5) units from 5.2 (± 0.5) to 0.6 (± 0.2) (P < 0.001) during the 30 min interval after administration. The onset of effect of betaine HCl was rapid, with a mean time to pH < 3 of 6.3 (± 4.3) min. The reacidification period was temporary with a gastric pH < 3 and < 4 lasting 73 (± 33) and 77 (± 30) min, respectively. Betaine HCl was well tolerated by all subjects. In healthy volunteers with pharmacologically induced hypochlorhydria, betaine HCl was effective at temporarily lowering gastric pH. The rapid onset and relatively short duration of gastric pH reduction gives betaine HCl the potential to aid the absorption of orally administered weakly basic drugs that exhibit pH-dependent solubility when administered under hypochlorhydric conditions.

Management of osteoporosis in CKD Stages 3 to 5.

Osteoporosis and chronic kidney disease (CKD) are both common conditions of older adults and both may be associated with substantial morbidity. However, biochemical and histologic changes that occur with progressive kidney disease require specific interventions, some of which may be concordant with osteoporosis management in the general population, whereas others may be less relevant or perhaps even harmful. In this article, we review the diagnosis of and management strategies for osteoporosis in individuals with CKD, placing these into perspective with the recently published KDIGO (Kidney Disease: Improving Global Outcomes) guidelines for treatment of CKD-mineral and bone disorder (CKD-MBD). Specifically, we highlight osteoporosis treatment recommendations by CKD stage and discuss new avenues for osteoporosis treatment that may be useful in individuals with CKD.

Clinical islet transplantation at the University of California, San Francisco.

The UCSF clinical islet transplant program has evolved to utilize immunosuppressive strategies that do not rely on CNIs or other nephro- and beta-cell-toxic immunosuppressive agents. These novel strategies depend on lymphocyte-depleting induction immunotherapy and maintenance immunosuppression with novel agents that focus on co-stimulation and/or lymphocyte migration blockade. These drugs are well tolerated, frequently allow establishment of insulin independence after single islet infusions, and minimize allosensitization. Our early results suggest these regimens will be attractive immunosuppressive agents for future protocols in allogeneic islet transplantation as well as protocols utilizing stem-cell-derived beta cells.

Kidney and liver transplantation in human immunodeficiency virus-infected patients: a pilot safety and efficacy study.

BACKGROUND: Human immunodeficiency virus (HIV)-infected patients have historically been excluded from consideration for transplantation out of concern for the effects of immunosuppression on the progression of HIV disease. Improvements in HIV-related morbidity and mortality with the use of highly active antiretroviral therapy (HAART) have prompted a reevaluation of transplantation as a treatment option for HIV-infected patients with end-stage kidney and liver disease. METHODS: Eligible patients met standard transplant criteria. They had undetectable plasma HIV-1 RNA levels (viral load) for 3 months (kidney) or were predicted to achieve viral load suppression posttransplantation if unable to tolerate HAART (liver); a CD4+ T-cell count of more than 200 cells/microL (kidney) or more than 100 cells/microL (liver) for 6 months; and no history of opportunistic infections and neoplasm. Standard immunosuppression included prednisone, mycophenolate mofetil (CellCept, Roche Pharmaceuticals, Basel, Switzerland), and cyclosporine (Neoral, Novartis, East Hanover, NJ). RESULTS: Fourteen patients received transplants (10 kidney transplants, mean follow-up 480 days; four liver transplants, mean follow-up 380 days). All of the kidney transplant recipients (100%) are alive and with functioning grafts, and three of four liver transplant patients (75%) are alive and well with functioning grafts (all liver transplant patients with normal liver function tests). The one death occurred 445 days posttransplantation in a liver recipient coinfected with hepatitis C virus, who died as the result of its rapid reoccurrence. Rejection occurred in 5 of 10 kidney transplant recipients but did not occur in any of the four liver transplant recipients. HIV viral loads have remained undetectable in all patients maintained with HAART. CD4 counts have remained stable in patients not treated for rejection. Patients receiving protease inhibitors require 25% of the dose of cyclosporine compared with patients receiving nonnucleoside reverse transcriptase inhibitors. CONCLUSIONS: There has been no evidence of significant HIV progression and no adverse effect of HIV on allograft function. Rejection is a concern in kidney transplant recipients, as is the possible poor outcome in hepatitis C virus-coinfected liver transplant recipients. Preliminary data are encouraging and indicate that transplantation should be a treatment option for individuals with well-controlled HIV disease.