Aspirin pharmacokinetics and pharmacodynamics through gestation

BACKGROUND

Low dose aspirin is recommended for prevention of preeclampsia, however there is not consensus on the appropriate dose. Pregnancy specific changes have the potential to impact the pharmacology of aspirin in pregnancy, however there are very limited studies on aspirin pharmacokinetics in pregnancy and none linking pharmacokinetics (PK, drug dose and drug level) to pharmacodynamics (PD, drug dose and physiologic response) in pregnancy. As a result, we do not have a good understanding of the pharmacologic response to aspirin in pregnancy, which has important implications for clinical efficacy. We sought to describe the PK and PD of aspirin through pregnancy and to identify individual covariates that impacted aspirin PK/PD.

OBJECTIVE

We sought to describe the PK and PD of aspirin through pregnancy (first and third trimester), to identify covariates that significantly impact aspirin PK and to identify the relationship between aspirin PK and PD.

STUDY DESIGN

This is a prospective study of patients at high risk for preeclampsia recommended to take 81 mg aspirin daily. This study involved 3 visits as follows: (1) baseline, first trimester (10-16 weeks of gestation) 6-hour PK visit, done before initiation of aspirin; (2) follow-up 1: 2 to 4 weeks after aspirin initiation; and (3) follow-up 2: third trimester 6-hour PK visit (28-32 weeks of gestation). The following were assessed at each visit: weight or body mass index, platelet function analysis-100 (Siemens), urinary thromboxane B2, serum thromboxane B2, and plasma salicylic acid. The PK visits consisted of blood work done at baseline (predose), administration of 81 mg nonenteric coated aspirin, and then plasma blood level of salicylic acid assessed at 30 minutes and then hourly 1 to 6 hours after dose. Pearson correlation and multivariable regression were used to identify associations between parameters and identify relevant covariates. Log-adjusted values were used for regression analysis. P<.05 was considered statistically significant.

RESULTS

Nineteen participants were included with first trimester data, and 16 with third trimester data. There was no statistically significant change in mean PK parameters between the first and third trimester, although there was a trend to lower peak concentration in the third than in the first trimester (P=.08). In multivariable regression, baseline obesity and current body mass index as a continuous measures were negatively associated with log-adjusted peak salicylic acid concentration (-0.28 [-0.46 to -0.11], P=.003 and -0.02 [-0.03 to -0.009], P=.001, respectively) and log-adjusted plasma salicylic acid area under the curve 0 to 6 hours postdose (-0.25 [-0.45 to 0.05], P=.02, -0.04 [-0.07 to -0.01], P=.008 respectively). There was a significant decrease in urinary thromboxane 2 to 4 weeks after aspirin initiation compared with baseline, which correlated with a concomitant increase in platelet function analysis-100 closure time. In multivariable regression model, there was a strong association between plasma salicylic acid concentration (area under the curve 0-6 hours postdose) and urinary thromboxane (B=-3.12 [-5.38 to -1.04], P=.006), and with urinary thromboxane suppression and platelet inhibition, platelet function analysis-100 (-0.23 [-0.31 to -0.14], P<.001). With progressive thromboxane suppression, platelet inhibition (platelet function analysis-100 closure time) increased. Individual comorbidities, including weight, hypertension, and pregestational diabetes (Type I or II), also impacted aspirin response.

CONCLUSION

We have demonstrated the relationship between individual factors, plasma concentrations of salicylic acid, thromboxane suppression, and platelet inhibition at a single dose (81 mg) of aspirin taken through pregnancy. Our findings suggest that dose modification of aspirin in pregnancy may help to achieve the optimal response. Our results may be used to facilitate computational modeling to identify optimal dosing, taking into consideration individual factors.

Population pharmacokinetic and safety analysis of ropivacaine used for erector spinae plane blocks

INTRODUCTION

Erector spinae plane blocks have become popular for thoracic surgery. Despite a theoretically favorable safety profile, intercostal spread occurs and systemic toxicity is possible. Pharmacokinetic data are needed to guide safe dosing.

METHODS

Fifteen patients undergoing thoracic surgery received continuous erector spinae plane blocks with ropivacaine 150 mg followed by subsequent boluses of 40 mg every 6 hours and infusion of 2 mg/hour. Arterial blood samples were obtained over 12 hours and analyzed using non-linear mixed effects modeling, which allowed for conducting simulations of clinically relevant dosing scenarios. The primary outcome was the Cmax of ropivacaine in erector spinae plane blocks.

RESULTS

The mean age was 66 years, mean weight was 77.5 kg, and mean ideal body weight was 60 kg. The mean Cmax was 2.5 ±1.1 mg/L, which occurred at a median time of 10 (7-47) min after initial injection. Five patients developed potentially toxic ropivacaine levels but did not experience neurological symptoms. Another patient reported transient neurological toxicity symptoms. Our data suggested that using a maximum ropivacaine dose of 2.5 mg/kg based on ideal body weight would have prevented all toxicity events. Simulation predicted that reducing the initial dose to 75 mg with the same subsequent intermittent bolus dosing would decrease the risk of toxic levels to <1%.

CONCLUSION

Local anesthetic systemic toxicity can occur with erector spinae plane blocks and administration of large, fixed doses of ropivacaine should be avoided, especially in patients with low ideal body weights. Weight-based ropivacaine dosing could reduce toxicity risk.

TRIAL REGISTRATION NUMBER

NCT04807504; clinicaltrials.gov.

Improved Tumor Control Following Radiosensitization with Ultrasound-Sensitive Oxygen Microbubbles and Tumor Mitochondrial Respiration Inhibitors in a Preclinical Model of Head and Neck Cancer

Tumor hypoxia (oxygen deficiency) is a major contributor to radiotherapy resistance. Ultrasound-sensitive microbubbles containing oxygen have been explored as a mechanism for overcoming tumor hypoxia locally prior to radiotherapy. Previously, our group demonstrated the ability to encapsulate and deliver a pharmacological inhibitor of tumor mitochondrial respiration (lonidamine (LND)), which resulted in ultrasound-sensitive microbubbles loaded with O₂ and LND providing prolonged oxygenation relative to oxygenated microbubbles alone. This follow-up study aimed to evaluate the therapeutic response to radiation following the administration of oxygen microbubbles combined with tumor mitochondrial respiration inhibitors in a head and neck squamous cell carcinoma (HNSCC) tumor model. The influences of different radiation dose rates and treatment combinations were also explored. The results demonstrated that the co-delivery of O₂ and LND successfully sensitized HNSCC tumors to radiation, and this was also enhanced with oral metformin, significantly slowing tumor growth relative to unsensitized controls (p < 0.01). Microbubble sensitization was also shown to improve overall animal survival. Importantly, effects were found to be radiation dose-rate-dependent, reflecting the transient nature of tumor oxygenation.

Development and Preclinical Investigation of Physically Cross-Linked and pH-Sensitive Polymeric Gels as Potential Vaginal Contraceptives

This study explored the development of cross-linked gels to potentially provide a physical barrier to vaginal sperm transport for contraception. Two types of gels were formulated, a physically cross-linked iota-carrageenan (Ci) phenylboronic acid functionalized hydroxylpropylmethyacrylate copolymer (PBA)-based (Ci-PBA) gel, designed to block vaginal sperm transport. The second gel was pH-shifting cross-linked Ci-polyvinyl alcohol-boric acid (Ci-PVA-BA) gel, designed to modulate its properties in forming a viscoelastic, weakly cross-linked transient network (due to Ci gelling properties) on vaginal application (at acidic pH of ~3.5-4.5) to a more elastic, densely cross-linked (due to borate-diol cross-linking) gel network at basic pH of 7-8 of seminal fluid, thereby acting as a physical barrier to motile sperm. The gels were characterized for dynamic rheology, physicochemical properties, and impact on sperm functionality (motility, viability, penetration). The rheology data confirmed that the Ci-PBA gel was formed by ionic interactions whereas Ci-PVA-BA gel was chemically cross-linked and became more elastic at basic pH. Based on the screening data, lead gels were selected for in vitro sperm functionality testing. The in vitro results confirmed that the Ci-PBA and Ci-PVA-BA gels created a barrier at the sperm-gel interface, providing sperm blocking properties. For preclinical proof-of-concept, the Ci-PBA gels were applied vaginally and tested for contraceptive efficacy in rabbits, demonstrating only partial efficacy (40-60%). Overall, the in vitro and in vivo results support the development and further optimization of cross-linked gels using commercially available materials as vaginal contraceptives.

Development of a Dual Drug-Loaded, Surfactant-Stabilized Contrast Agent Containing Oxygen

Co-delivery of cancer therapeutics improves efficacy and encourages synergy, but delivery faces challenges, including multidrug resistance and spatiotemporal distribution of therapeutics. To address these, we added paclitaxel to previously developed acoustically labile, oxygen-core, surfactant-stabilized microbubbles encapsulating lonidamine, with the aim of developing an agent containing both a therapeutic gas and two drugs acting in combination. Upon comparison of unloaded, single-loaded, and dual-loaded microbubbles, size (~1.7 µm) and yield (~2 × 10⁹ microbubbles/mL) (~1.7) were not statistically different, nor were acoustic properties (maximum in vitro enhancements roughly 18 dB, in vitro enhancements roughly 18 dB). Both drugs encapsulated above required doses calculated for head and neck squamous cell carcinoma, the cancer of choice. Interestingly, paclitaxel encapsulation efficiency increased from 1.66% to 3.48% when lonidamine was included. During preparation, the combination of single drug-loaded micelles gave higher encapsulation (µg drug/g microbubbles) than micelles loaded with either drug alone (lonidamine, 104.85 ± 22.87 vs. 87.54 ± 16.41), paclitaxel (187.35 ± 8.38 vs. 136.51 ± 30.66). In vivo intravenous microbubbles produced prompt ultrasound enhancement within tumors lasting 3–5 min, indicating penetration into tumor vasculature. The ability to locally destroy the microbubble within the tumor vasculature was confirmed using a series of higher intensity ultrasound pulses. This ability to locally destroy microbubbles shows therapeutic promise that warrants further investigation.

Randomized trial of prophylactic antibiotics vs. placebo after midshaft-to-distal hypospadias repair: the PROPHY Study

BACKGROUND

Use of prophylactic antibiotics after stented hypospadias repair is very common, but most research has not identified any clinical benefits of this practice. Only one study has found that postoperative prophylaxis reduces symptomatic urinary tract infections (UTIs). Data from the same trial suggested that prophylaxis may also reduce urethroplasty complications. No studies on this subject have been placebo-controlled.

OBJECTIVE

We performed a randomized, double-blind, placebo-controlled study to evaluate the effect of postoperative prophylactic antibiotics on the incidence of infection or urethroplasty complications after stented repair of midshaft-to-distal hypospadias.

STUDY DESIGN

Boys were eligible for this multicenter trial if they had a primary, single-stage repair of mid-to-distal hypospadias with placement of an open-drainage urethral stent for an intended duration of 5-10 days. Participants were randomized in a double-blind fashion to receive oral trimethoprim-sulfamethoxazole or placebo twice daily for 10 days postoperatively. The primary outcome was a composite of symptomatic UTI, surgical site infection (SSI), and urethroplasty complications, including urethrocutaneous fistula, meatal stenosis, and dehiscence. Secondary outcomes included each component of the primary outcome as well as acute adverse drug reactions (ADRs) and C. difficile colitis.

RESULTS

Infection or urethroplasty complications occurred in 10 of 45 boys (22%) assigned to receive antibiotic prophylaxis as compared with 5 of 48 (10%) who received placebo (relative risk [RR], 2.1; 95% confidence interval [CI], 0.8 to 5.8; p = 0.16). There were no significant differences between groups in symptomatic UTIs, SSIs, or any urethroplasty complications. Mild ADRs occurred in 3 of 45 boys (7%) assigned to antibiotics as compared with 5 of 48 (10%) given placebo (RR, 0.6; 95% CI, 0.2 to 2.5; p = 0.72). There were no moderate-to-severe ADRs, and no patients developed C. difficile colitis.

CONCLUSIONS

In this placebo-controlled trial of 93 patients, prophylactic antibiotics were not found to reduce infection or urethroplasty complications after stented mid-to-distal hypospadias repair. The study did not reach its desired sample size and was therefore underpowered to independently support a conclusion that prophylaxis is not beneficial. However, the result is consistent with most prior research on this subject.

GOV IDENTIFIER

NCT02096159.

Stability of extemporaneously compounded 5-fluorouracil utilizing high performance liquid chromatography

The goal of the current study is to determine stability of compounded 5-fluorouracil (5-FU) in Intravia™ bags and CADD™ cassettes stored up to 15 days under refrigeration (2-8°C) and room temperature (25°C with 60% relative humidity), with four different concentrations (20 mg/mL, 30 mg/mL, 40 mg/mL, and 50 mg/mL) and two diluents (0.9% sodium chloride and 5% dextrose). A stability-indicating high-performance liquid chromatography (HPLC) method was developed to analyze the 5-FU concentrations. The stability of compounded 5-FU infusions was investigated using this method. Two samples from each storage condition were assessed for stability on days 0, 4, 7, 10, and 15 as per United States Pharmacopeia (USP) guidelines. The assay of 5-FU was done utilizing a calibrated stability-indicating HPLC method. The stability-indicating HPLC assay showed 5-FU completely degraded within 1 hour in basic conditions. No cloudiness or color change was observed during the stability study. Precipitation was observed in the CADD™ cassettes at day 15 in both storage conditions and at day 10 in a single room-temperature CADD™ cassette for 40 mg/mL in 5% dextrose (D5W). HPLC assay revealed the infusions in CADD™ cassettes retained greater than 90% of the initial concentrations of 5-FU for 15 days stored at room temperature (25°C and 60% relative humidity) and for 10 days at refrigeration (2-8°C). Intravia™ bags retained stability through 15 days for all the compounded 5-FU concentrations and both the storage conditions. 5-FU infusions in both CADD™ cassettes and Intravia™ bags were stable for extendable periods in multiple concentrations compared to recommended guidelines for hospital use.

Longitudinal evaluation of azithromycin and cytokine concentrations in amniotic fluid following one-time oral dosing in pregnancy

To utilize noninvasive collection of amniotic fluid in the setting of preterm premature rupture of membranes (PPROMs) to report the time concentration profile of azithromycin in amniotic fluid over 7 days from a single dose, and evaluate the correlation between azithromycin concentration and inflammatory markers in amniotic fluid. Prospective cohort study of five pregnant patients admitted with PPROMs and treated with a single 1 g oral azithromycin dose. Amniotic fluid was collected from pads and used to quantify azithromycin concentration as well as TNFa, IL-1a, IL-1b, IL-6, IL-8, and IL-10 concentrations. Primary outcome was time/concentration profile of azithromycin in amniotic fluid. Secondary outcome included correlation between azithromycin concentration and cytokine concentrations. Five patients were enrolled. Mean gestational age on admission with PPROM was 27.5 ± 2.3 weeks with a median latency of 7 days (interquartile range [IQR] = 4-13). A median of two samples/day (IQR = 1-3) were collected per participant. Azithromycin was quantified in duplicate; intra-assay coefficient of variation was 17%. Azithromycin concentration was less than 60 ng/ml after day 3. Azithromycin concentration was positively correlated with IL-8 (r = 0.38, p = 0.03), IL1a (r = 0.39, p = 0.03), and IL-1b (r = 0.36, p = 0.04) in amniotic fluid. Azithromycin is detectable in amniotic fluid over 7 days from a single 1 g maternal dose, however, it is not sustained over the range of minimum inhibitory concentration for common genitourinary flora. Based on correlation with specific cytokines, azithromycin penetration in amniotic fluid may relate to maternal monocyte concentration in amniotic fluid in the setting of PPROM.

Stability-indicating HPLC method to determine the stability of extemporaneously prepared vancomycin oral solution cups

PURPOSE

To determine the stability of compounded sweetened vancomycin oral formulations in plastic unit dose cups stored up to 180 days under 2 temperature conditions: refrigeration (2°C-6°C) and room temperature (25°C with 60% relative humidity).

METHODOLOGY

A stability-indicating high-performance liquid chromatography (HPLC) method was developed to analyze vancomycin in the presence of degradation peaks. The stability of extemporaneously compounded vancomycin solution stored in oral unit dose cups was investigated using this method. The tested vancomycin oral solutions were compounded formulations of 125 mg/2.5 mL and 500 mg/10 mL. Three oral unit dose cups from each storage condition were withdrawn and assessed for stability on days 0, 3, 7, 15, 22, 30, 90, 120, 150, and 180 as per United States Pharmacopeia guidelines. The assay of vancomycin was carried out by using a calibrated stability-indicating HPLC method.

RESULTS

The stability-indicating HPLC assay showed that vancomycin completely degraded within 2 hours when exposed to highly acidic or basic pH conditions. No precipitation, cloudiness, or color changes were observed during the study under either temperature condition. The HPLC assay revealed that vancomycin oral solution cups retained greater than 90% of the initial concentrations of vancomycin for 30 days when stored at room temperature (25°C and 60% relative humidity) and for 180 days with refrigeration (2°C-6°C).

CONCLUSION

Vancomycin oral formulations were stable for long-term storage periods beyond those specified in manufacture guidelines. Our data suggests the extended stability of vancomycin oral solutions compounded for hospital use can be extended.

Stability-indicating LC-MS Method for Determination of Stability of Extemporaneously Compounded Buprenorphine Oral Syringes for Neonatal Abstinence Syndrome

OBJECTIVE

In the hospital settings, buprenorphine is used for the treatment of patients with neonatal abstinence syndrome. It is extemporaneously compounded and stored in oral plastic syringes. However, limited information exists about the stability of buprenorphine and its compounded formulations when stored under specific conditions. Hence, we developed a stability-indicating high-performance liquid chromatography-mass spectrometry (LC-MS) method to analyze the stability of buprenorphine over time.

METHODS

A stability-indicating LC-MS method was developed to map the potential degradation peaks of buprenorphine when exposed to acidic, basic, and oxidative conditions. This method was used to study the stability of compounded buprenorphine oral syringes stored under refrigeration (2°C-8°C) and room temperature (25°C ± 2°C with 60% relative humidity). Syringes from each storage condition were assessed for stability using pH meter and stability-indicating LC-MS assay for 30 days.

RESULTS

Buprenorphine gets completely degraded in the presence of acid at the end of 1 hour of exposure. Various degradation peaks were identified using LC-MS assay for buprenorphine under acidic, basic, and peroxide conditions. Stability study of oral buprenorphine syringes showed no precipitation, cloudiness, or color change during this study at all storage conditions. The LC-MS assay revealed that buprenorphine oral syringes retained greater than 90% of the initial concentrations for 30 days.

CONCLUSIONS

Highly sensitive stability-indicating LC-MS method was developed for studying the stability of extemporaneously compounded buprenorphine oral syringes. This study demonstrates that buprenorphine extemporaneous formulation prepared according to the manufacturers' recommendations is stable under refrigerated or room temperature conditions for 30 days in oral plastic syringes.

Metabolic plasticity imparts erlotinib-resistance in pancreatic cancer by upregulating glucose-6-phosphate dehydrogenase

Pancreatic ductal adenocarcinoma (PDAC) is one of the most malignant forms of cancer. Lack of effective treatment options and drug resistance contributes to the low survival among PDAC patients. In this study, we investigated the metabolic alterations in pancreatic cancer cells that do not respond to the EGFR inhibitor erlotinib. We selected erlotinib-resistant pancreatic cancer cells from MiaPaCa2 and AsPC1 cell lines. Metabolic profiling of erlotinib-resistant cells revealed a significant downregulation of glycolytic activity and reduced level of glycolytic metabolites compared to the sensitive cells. The resistant cells displayed elevated expression of the pentose phosphate pathway (PPP) enzymes involved in ROS regulation and nucleotide biosynthesis. The enhanced PPP elevated cellular NADPH/NADP+ ratio and protected the cells from reactive oxygen species (ROS)-induced damage. Inhibition of PPP using 6-aminonicotinamide (6AN) elevated ROS levels, induced G1 cell cycle arrest, and sensitized resistant cells to erlotinib. Genetic studies identified elevated PPP enzyme glucose-6-phosphate dehydrogenase (G6PD) as an important contributor to erlotinib resistance. Mechanistically, our data showed that upregulation of inhibitor of differentiation (ID1) regulates G6PD expression in resistant cells thus contributing to altered metabolic phenotype and reduced response to erlotinib. Together, our results highlight an underlying role of tumor metabolism in PDAC drug response and identify G6PD as a target to overcome drug resistance.

LC-MS based stability-indicating method for studying the degradation of lonidamine under physical and chemical stress conditions

Background and purpose:

Lonidamine is a hexokinase II inhibitor, works as an anticancer molecule, and is extensively explored in clinical trials. Limited information prevails about the stability-indicating methods which could determine the forced degradation of lonidamine under stressed conditions. Hence, we report the use of a rapid, sensitive, reproducible, and highly accurate liquid chromatography and mass spectrometry method to analyze lonidamine degradation.

Experimental approach:

The Xbridge BEH shield reverse phase C18 column (2.5 μm, 4.6 × 75 mm) using isocratic 50:50 water: acetonitrile with 0.1% formic acid can detect lonidamine with help of mass spectrometer in tandem with an ultraviolet (UV) detector at 260 nm wavelength.

Findings/ Results:

A linear curve with r² > 0.99 was obtained for tandem liquid chromatography-mass spectrometry (LC-MS)-UV based detections. This study demonstrated (in the present set up of isocratic elution) that LC-MS based detection has a relatively high sensitivity (S/N (10 ng/mL): 220 and S/N (20 ng/mL): 945) and accuracy at lower detection and quantitation levels, respectively. In addition to developing the LC-MS method, we also report that the current method is stability-indicating and shows that lonidamine gets degraded over time under all three stress conditions; acidic, basic, and oxidative.

Conclusion and implications:

LC-MS based quantitation of lonidamine proved to be a better method compared to high-performance liquid chromatography (HPLC)-UV detections for mapping lonidamine degradation. This is the first report on the stability-indicating method for studying the forced degradation of lonidamine using LC-MS method.

Symptoms of gluten ingestion in patients with non-celiac gluten sensitivity: A randomized clinical trial

OBJECTIVES

Non-celiac gluten sensitivity (NCGS) is the presence of symptoms induced by gluten and relieved by a gluten-free diet (GFD) in patients without celiac disease or wheat allergy. Studies are mixed as to whether gluten is the main symptom trigger in patients with NCGS. Gluten immunogenic peptides (GIPs) in stool and urine are novel methods to monitor GFD compliance. Few studies have investigated their use in patients with NCGS. The aim of this study was to assess whether patients with NCGS have increased symptoms with gluten ingestion and to assess compliance with the GFD using stool and urine GIPs.

METHOD

This was a prospective, randomized, double-blinded crossover trial evaluating symptoms in patients with NCGS. Thirty patients with NCGS and 43 healthy controls were placed on a GFD. Patients received 0.5 or 2 g/d of gluten for 7 d each. The remaining weeks, they received placebo for a total of 4 wk. Symptoms were evaluated weekly using the Celiac Symptom Index (CSI). Urine and stool samples were collected weekly and measured for the detection of GIPs to detect exposure to gluten.

RESULTS

There was no difference in symptom severity within the NCGS group whether receiving placebo or gluten (32.69 versus 31.54, P = 0.64). Patients with NCGS had significantly higher CSI scores at baseline than healthy controls. Patients with NCGS were less likely to have stool and urine GIPs than healthy patients.

CONCLUSION

Patients with NCGS were more adherent to the GFD based on stool and urine GIP results. Patients with NCGS had increased symptom severity at baseline compared with healthy controls. Neither group had significantly increased symptoms after ingestion of gluten.

Compatibility of treprostinil sodium and dopamine hydrochloride during simulated Y-site administration

PURPOSE

To evaluate the physical and chemical compatibilities of treprostinil sodium and dopamine hydrochloride.

METHODS

Treprostinil sodium (4,000, 76,000, and 500,000 ng/mL) were mixed with dopamine hydrochloride (0.6, 3.2, 6, and 40 mg/mL). Samples were obtained at hours 0, 1, 2, and 4 for physical compatibility and chemical stability testing. Physical compatibility was assessed by visual examination and measurements of turbidity and pH. Drug concentrations were assessed using stability-indicating liquid chromatography mass spectrophotometry (LCMS) for treprostinil sodium and stability-indicating high-performance liquid chromatography (HPLC) for dopamine hydrochloride.

RESULTS

Treprostinil sodium 4,000 and 76,000 ng/mL, when mixed with dopamine hydrochloride 0.6, 3.2, 6, and 40 mg/mL, were stable for 4 hours. Treprostinil sodium 500,000 ng/mL was stable when mixed with dopamine hydrochloride 0.6 mg/mL for 4 hours, but when mixed with dopamine hydrochloride 3.2, 6, and 40 mg/mL, significant precipitation was seen.

CONCLUSION

Treprostinil sodium 4,000 and 76,000 ng/mL were stable for 4 hours during simulated Y-site coadministration with dopamine hydrochloride 0.6, 3.2, 6, and 40 mg/mL. Treprostinil sodium 500,000 ng/mL is stable when mixed with dopamine hydrochloride 0.6 mg/mL.

Expression of Tryptophan 2,3-Dioxygenase in Metastatic Uveal Melanoma

Uveal melanoma (UM) is the most common primary eye malignancy in adults and up to 50% of patients subsequently develop systemic metastasis. Metastatic uveal melanoma (MUM) is highly resistant to immunotherapy. One of the mechanisms for resistance would be the immune-suppressive tumor microenvironment. Here, we have investigated the role of tryptophan 2,3-dioxygenase (TDO) in UM. Both TDO and indoleamine 2,3-dioxygenase (IDO) catalyze tryptophan and produce kynurenine, which could cause inhibition of T cell immune responses. We first studied the expression of TDO on tumor tissue specimens obtained from UM hepatic metastasis. High expression of TDO protein was confirmed in all hepatic metastasis. TDO was positive in both normal hepatocytes and the tumor cells with relatively higher expression in tumor cells. On the other hand, IDO protein remained undetectable in all of the MUM specimens. UM cell lines established from metastasis also expressed TDO protein and increasing kynurenine levels were detected in the supernatant of MUM cell culture. In TCGA database, higher TDO2 expression in primary UM significantly correlated to BAP1 mutation and monosomy 3. These results indicate that TDO might be one of the key mechanisms for resistance to immunotherapy in UM.

Simultaneous quantitative LC-MS method of ketamine, midazolam and their metabolites (dehydronorketamine, norketamine and 1hydroxymidazolam) for its application in patients on extracorporeal membrane oxygenation (ECMO) therapy

Ketamine (Ket) and midazolam (MDZ) are commonly administered drugs in the intensive care setting for analgesia and sedation. Ket and MDZ are metabolized to dehydro-norketamine (DHNK), nor-ketamine (NK) and 1-hydroxy midazolam (1HMDZ). Limited studies evaluating their pharmacokinetics exists in patients on extracorporeal membrane oxygenation (ECMO) therapy. Therefore, we developed a quantitative, high-performance liquid chromatography-mass spectrometry (with single ion monitoring) method to simultaneously detect Ket, MDZ and their (DHNK, NK and 1HMDZ) metabolites in human plasma. Considerable sensitivity was obtained for the analytes using a C₁₈ HILIC column operated by a high-performance liquid chromatography system coupled with a Thermo Exactive Orbitrap mass spectrometer. Calibration curves were developed for analyte molecules (n = 5) in the presence of carbamazepine (CBZ) as an internal standard. The lower limits of quantitation (LLOQ) for Ket and MDZ were 20 and 10 ng/mL, respectively with the LLOQ for DHNK, NK and 1HMDZ at 470, 320 and 150 ng/ml. Moreover, the percent coefficient of variance and precision for inter- and intra-day runs were within the standards set forth by the ICH and FDA guidelines. This method is sensitive and has been successfully applied to an ongoing pharmacokinetic study in patients on ECMO therapy.

Abstract 243: Differential effects of combination treatment of biochanin A and statins on glioblastoma multiforme cell proliferation and cell metabolism

Glioblastoma Multiforme (GBM) is a deadly brain cancer and represents the most common central nervous system (CNS) tumors in adults. Although GBM does not metastasize, its aggressive growth and invasive nature are responsible for poor patient prognosis. The current standard therapy for newly diagnosed GBM patients involves surgical resection, followed by radiation and chemotherapy with Temozolomide. However, its rapid rate of infiltration into normal brain tissue ultimately renders the therapy ineffective. Epidemiological studies on dietary isoflavones (e.g., genistein, biochanin A) have shown their anti-cancer potential in different cancers. Though primarily used in management of hyperlipidemia and cardiovascular diseases, statins are known to exert anti-proliferative effects. We therefore hypothesized that a combination treatment of biochanin A & statins (e.g., Atorvastatin, Lovastatin, Simvastatin, Fluvastatin and Pravastatin) exerts enhanced anticancer effects on GBM U-87 MG and T98 G cells. Our studies showed statins induced differential effects on viability of GBM cells in combination with biochanin A, with U-87 MG being more susceptible than T98 G cells. The combination treatment of biochanin A and atorvastatin also decreased invasion in U-87 MG cells. Additionally, cell metabolism studies using seahorse XFp analyzer showed a switch in their metabolic phenotype with an increase in mitochondrial respiration and a decrease in glycolytic activity with the combination treatment. We also performed metabolite extraction on GBM cells for a global unbiased profiling of metabolites using a single extraction procedure and dual separation analysis by LCMS. A differential analysis of alternative GBM treatment indicated statistically significant changes in carbohydrate and amino acid metabolism as well as alterations to various degradation pathway intermediates. Together, the combination treatment-induced effects on GBM cell lines are differential and our results may have potential implications in developing combination therapies with biochanin A in vivo and support the design of new and better therapies for the treatment of a lethal cancer like GBM.

Citation Format: Vilas S. Desai, Eric Buchhalter, Max Cabanzo, Arushi Tiwari, Gagan Kaushal, James C. Lai, Alok Bhushan. Differential effects of combination treatment of biochanin A and statins on glioblastoma multiforme cell proliferation and cell metabolism [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 243.

Pharmacokinetics of Ketamine at Dissociative Doses in an Adult Patient With Refractory Status Asthmaticus Receiving Extracorporeal Membrane Oxygenation Therapy

PURPOSE

First-line management of severe asthma exacerbations include the use of inhaled short-acting β-agonists, anticholinergics, and systemic corticosteroids. Continuous intravenous ketamine given at dissociative doses may be a pharmacologic option in patients who are intubated with life-threatening severe bronchospasm unresponsive to standard therapy. We describe the case of a 44-year-old man admitted to the intensive care unit for status asthmaticus requiring intubation and mechanical ventilation.

METHODS

The patient developed severe refractory hypercapnic respiratory failure necessitating additional respiratory support with veno-venous extracorporeal membrane oxygenation (ECMO) therapy. Ketamine treatment was initiated at 0.5 mg/kg/h continuous infusion on the day of admission for pain control and required up-titration to 2 mg/kg/h by intensive care unit day 4 for bronchodilation. Whole blood samples were obtained for pharmacokinetic analysis of ketamine during ECMO.

FINDINGS

The plasma concentration at steady state was 1018.7 ng/mL, with an estimated clearance of 1.96 L/kg/h after up-titration. The V_d was 14.18 L/kg, the k_e was 0.14 hr^-1, and the t_½ was 5 hours.

IMPLICATIONS

Compared with healthy adults, there was a 6.5-fold increase in the V_d. However, the V_d was similar compared with critically ill patients not receiving ECMO. Further studies should focus on the effect of ECMO on ketamine pharmacokinetic properties.

D-cycloserine nasal formulation development for anxiety disorders by using polymeric gels

D-cycloserine (DCS), a partial agonist at N-methyl-D-aspartate (NMDA) receptors, is used as an enhancer of exposure therapy for anxiety disorders. The purpose of the present study was to investigate the feasibility of using polymeric gels to increase the viscosity of the formulation and thereby increase the nasal residence time and sustained release of DCS in vitro. Hydroxypropyl methylcellulose (HPMC), hydroxypropyl cellulose (HPC), and methyl cellulose (MC) were prepared at concentrations of 0.5 to 5% w/v. Pluronic F-127 (PF-127) was prepared at concentrations of 15 to 35% w/v. pH, viscosity and in vitro DCS release behavior of the formulated gels were analyzed. All four gels that were tested, demonstrated sustained DCS release behavior over a 24-hour period, but with different rates. Based on the results of this study, HPMC, HPC, MC, and PF-127 are capable of increasing the viscosity of nasal gel formulations and of releasing DCS in sustained manner. Therefore, these polymeric gels can be suitable carriers for DCS nasal gel formulation.

Dental Care-Related Fear and Anxiety: Distress Tolerance as a Possible Mechanism

Distress tolerance, the degree to which one is able to cope with and endure negative emotional states, has been broadly applied to understand and treat a variety of health (including behavioral) problems, but little is known about its role in oral health care and specifically dental care-related fear and anxiety, making it a novel construct in the oral health care literature. This cross-sectional study examined distress tolerance as a possible predictor of dental fear and anxiety among a sample of adults with and without diagnoses of dental phobia, investigated possible differences in levels of distress tolerance between adults with and without dental phobia, and determined possible associations between distress tolerance and fear of pain, anxiety sensitivity, and depression. Using 52 volunteers (n = 31, dental phobia group; n = 21, healthy comparison group), this investigation used self-report measures of distress tolerance, fear of pain, anxiety sensitivity, dental fear, and depression. The Anxiety Disorders Interview Schedule, a semi-structured interview, was used to assess for dental phobia and other psychological disorders. Distress tolerance significantly predicted dental fear and anxiety, even after controlling for age, sex, fear of pain, anxiety sensitivity, and depression. In addition, the dental phobia group had lower distress tolerance than the healthy comparison group. Distress tolerance was significantly associated with fear of pain, anxiety sensitivity, and depression. Findings indicate that low distress tolerance plays a unique and distinct role as a possible mechanism in the genesis of dental care-related fear and anxiety and phobia and may exacerbate the experience of other states, including fear of pain and anxiety sensitivity. Knowledge Transfer Statement: Results indicate that patients who have a lower ability to tolerate emotional and physical distress may have higher levels of dental care-related fear and anxiety and even dental phobia, as well as associated sequelae (e.g., avoidance of dental care). Treatment of highly fearful dental patients may helpfully include a focus on increasing distress tolerance.

A randomized placebo-controlled pilot study of the efficacy and safety of D-cycloserine in people with chronic back pain

BACKGROUND

Few effective pharmacological treatment options exist for chronic back pain, the leading cause of disability in the US, and all are associated with significant adverse effects.

OBJECTIVE

To determine the efficacy and safety of D-cycloserine, a partial agonist to the N-methyl-D-aspartate receptor, in the treatment of chronic low back pain.

METHODS

A total of 41 participants with chronic back pain who met all inclusion and exclusion criteria were enrolled in a double-blind, placebo-controlled randomized pilot trial of D-cycloserine. Treatment was administered orally for six weeks at escalating daily doses of 100 mg, 200 mg, and 400 mg, each for two weeks. The primary outcome measure was back pain intensity using the Numeric Rating Scale (0-10). Secondary measures were back pain-related questionnaires: McGill Pain Questionnaire short form, painDETECT, PANAS, and BDI. The pre-specified analysis was a two-way repeated measures analysis of variance.

RESULTS

A treatment difference was observed between groups treated with D-cycloserine and placebo at six weeks of 1.05 ± 3.1 units on the Numeric Rating Scale, with an effect size of 0.4 and p = 0.14. This trend of better chronic back pain relief with D-cycloserine was also observed in the secondary measures. No safety issues were seen.

CONCLUSION

The difference in mean pain between the D-cycloserine and placebo groups did not reach statistical significance. However, a clinically meaningful effect size in the magnitude of pain relief was observed with a consistent pattern across multiple outcome measures with good safety, supporting further research into the effectiveness of D-cycloserine for chronic back pain.

Abstract LB-049: Differential effects of functionalized and non-functionalized short multi-wall carbon nanotubes on survival of pancreatic cancer cells

Pancreatic cancer is an aggressive type of cancer with poor prognosis and low five-year survival rate. Current treatments such as chemotherapy and radiation therapy are not effective. Thus, new therapeutic strategies are urgently needed to treat patients with this devastating disease and to improve their prognosis. Carbon nanotubes (CNTs) constitute a novel nanomaterial extensively studied to develop and exploit their potential in biomedical applications (e.g. drug delivery vehicles and diagnostic agents), including cancer nanobiomedicine. Modification of CNTs with functional groups may improve their aqueous solubility and selectively facilitate the attachment of drugs as well as macromolecules to CNTs, thereby creating new avenues for designing novel and highly targeted drugs. Even though the putative cytotoxicity of functionalized and non-functionalized CNTs is poorly understood, it can be gainfully exploited to enhance the efficacy of anti-cancer drugs. The aim is this study is to investigate the hypothesis that functionalized and non-functionalized CNTs exert differential cytotoxic effects on pancreatic cancer cells. We employed the MTT assay to determine the effects of functionalized and non-functionalized short multi-wall carbon nanotubes (SMWCNTs) on survival of PANC1 cells and Western-blot analysis to elucidate some of the cell survival/proliferation mechanisms (e.g., ERG) underlying the effects induced by SMWCNTs. We used the Seahorse XFp technology to examine the effects of the SMWCNTs on cellular energetics (especially glycolysis & mitochondrial metabolism) in pancreatic cancer cells. Additionally, we employed Annexin V/PI staining in combination with flow cytometry to determine the effects of SMWCNTs in inducing apoptosis in MiaPaca-2 cells. Dose-response studies on pancreatic cancer cells using the MTT assay indicated non-functionalized CNTs to be more cytotoxic than functionalized CNTs. Cell signaling studies indicate no alteration in AKT & phospho-AKT levels between functionalized & non-functionalized CNTs treatment. However, phospho-ERK levels were observed to consistently decrease with increasing concentrations of non-functionalized CNTs. Flow cytometric analysis showed increased apoptotic cell death with non-functionalized CNTs relative to that with functionalized CNTs. Overall, results from these studies indicate the differential effects of CNTs (functionalized versus non-functionalized) on pancreatic cancer cells and as such they may have implications in designing novel therapies for treatment of pancreatic cancer.

Citation Format: Alok Bhushan, Rutika Kokate, Vilas Desai, Annie Chhun, Gagan Kaushal, Yao Zhang, James Lai. Differential effects of functionalized and non-functionalized short multi-wall carbon nanotubes on survival of pancreatic cancer cells. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr LB-049.

Stability of extemporaneously compounded diltiazem hydrochloride infusions stored in polyolefin bags

PURPOSE

The stability of extemporaneously compounded diltiazem hydrochloride infusions stored in polyolefin bags was studied.

METHODS

Sterile preparations of diltiazem hydrochloride were compounded to a concentration of 1 mg/mL in 5% dextrose solutions in accordance with United States Pharmacopeia chapter 797. The infusions were stored at -20 °C, 2-6 °C, and 22-25 °C. Three samples from each temperature were withdrawn and assessed for stability immediately after preparation (day 0) and on days 7, 15, 21, and 30 using a high-performance liquid chromatography (HPLC) assay. The physical stability of diltiazem samples was assessed by visual examination. Infusions were evaluated against black and white backgrounds for evidence of visible particulate matter, cloudiness, and color changes. The concentration of diltiazem hydrochloride in all samples was examined using a stability-indicating HPLC method at each time point. Diltiazem was considered stable if the solution retained over 90% of the initial concentration.

RESULTS

No precipitation, cloudiness, or color change was observed at any of the temperatures studied. pH did not significantly increase or decrease among the samples, regardless of temperature, over the study period. The diltiazem hydrochloride infusions retained greater than 90% of the initial concentrations for at least 30 days.

CONCLUSION

Diltiazem hydrochloride diluted to 1 mg/mL in 5% dextrose injection was stable for 30 days when stored at -20 °C, 2-6 °C, and 22-25 °C.

Initial characterization of D-cycloserine for future formulation development for anxiety disorders

The purpose of this study is to characterize D-cycloserine (DCS) physicochemical properties to facilitate future formulation development of DCS for anxiety disorders. A stability-indicating HPLC assay method for the quantitation of DCS was developed and calibrated to be used for this study. The partition coefficient was determined and compared with the predicted value. The solution stability of DCS was studied under various pH (2.0-11.5) and ionic strengths of 10 and 20 mM at physiological temperature of 37°C. The 250 mg capsule was compounded to the nominal strength of 50 mg used for anxiety disorders. These capsules were then put under stability. The in vitro dissolution was also carried out at 37°C as per the United States Pharmacopeia (USP) guidelines. The partition coefficient value (Kp) determined for the DCS was log Kp = -2.89 ± 0.06 (n = 6). The pH-solution stability profile shows that DCS has maximum stability under alkaline conditions. The maximum rate of degradation was seen at pH of 4.7. The mean percent recovery of DCS from the capsules compounded to strength of 50 mg was 100.3 ± 1.4. The stability study of the reformulated capsules concluded that reformulated DCS is stable for at least one year at room temperature. The in vitro dissolution illustrates that all the DCS is released from the capsules in 10 min. The present characterization of DCS study will serve as guidance for the future directions regarding the reformulation of DCS in order to be used in anxiety disorders.

Extended Stability of Sodium Bicarbonate Infusions Prepared in Polyolefin Bags

Purpose

To investigate the stability of 0.1 mEq/mL and 0.15 mEq/mL strengths of extemporaneously compounded sodium bicarbonate preparations.

Methods

Sterile preparations of sodium bicarbonate of 2 strengths (0.1 mEq/mL and 0.15 mEq/mL) were compounded in accordance with USP <797> standards. To carry out the stability testing, these products were stored under 3 temperature conditions: −20°C, 2°C-8°C, and 23°C-25°C. Under the stability studies, pH, particulate matter, and the active content were monitored for 30 days.

Results

Sodium bicarbonate infusions are stable for 21 days when stored at −20°C or 2°C −8°C and are stable for 7 days when stored at room temperature (23°C-25°C). These data demonstrate that sodium bicarbonate infusions have extended physical and chemical stability after preparation.

Conclusions

The stability analysis results show that the observed shelf life was far better than the recommended expiration dates. This will allow the hospitals to give longer dating to sodium bicarbonate preparations, provided they are prepared in a sterile environment and are in compliance with USP <797> guidelines.

Extended Stability of Magnesium Sulfate Infusions Prepared in Polyolefin Bags

Purpose

To investigate the stability of extemporaneously compounded 50 g per 600 mL magnesium sulfate parenteral solution diluted in Lactated Ringer's solution.

Methods

The sterile preparations of magnesium sulfate were compounded in accordance with USP <797> standards. To carry out the stability testing, these products were stored under 3 different temperature conditions of −20°C, 2°C to 6°C, and 22°C to 25°C. Under the stability studies, pH, particulate matter, and the active content were monitored for 30 days.

Results

Magnesium sulfate infusions are stable for 30 days when stored at −20°C or 2°C to 6 °C and stable for 30 days under all the temperature conditions studied. These data demonstrate that magnesium sulfate infusions have an extended physical and chemical stability after preparation.

Conclusions

The stability analysis results show that the shelf-life observed was far better than their recommended expiration dates. This will allow the hospitals to give longer dating to magnesium sulfate preparations, provided they are prepared in a sterile environment and are in compliance with USP <797> guidelines.

Stability-indicating HPLC method for the determination of the stability of oxytocin parenteral solutions prepared in polyolefin bags

Oxytocin is very commonly used in clinical settings and is a nonapeptide hormone that stimulates the contraction of uterine smooth muscles. In this study the stability of extemporaneously compounded oxytocin solutions was investigated in polyolefin bags. The sterile preparations of oxytocin were compounded to the strength of 0.02 U/mL in accordance with United States Pharmacopeia (USP) <797> standards. In order to carry out the stability testing of these parenteral products, the solutions were stored under three different temperature conditions of -20°C (frozen), 2-6°C (refrigerated), and 22-25°C (room temperature). Three solutions from each temperature were withdrawn and were assessed for stability on days 0, 7, 15, 21, and 30 as per the USP guidelines. The assay of oxytocin was examined by an HPLC method at each time point. No precipitation, cloudiness or color change was observed during this study at all temperatures. The assay content by HPLC revealed that oxytocin retains greater than at least 90% of the initial concentrations for 21 days. There was no significant change in pH and absorbance values for 21 days under all the conditions of storage. Oxytocin parenteral solutions in the final concentration of 0.02 U/mL and diluted in normal saline are stable for at least 30 days under frozen and refrigerated conditions for 30 days. At the room temperature, the oxytocin solutions were stable for at least 21 days. The stability analysis results show that the shelf-life of 21 days observed in this study was far better than their recommended expiration dates.

Antimicrobial and toxicological studies of some metal complexes of 4-methylpiperazine-1-carbodithioate and phenanthroline mixed ligands

A few mixed ligand transition metal carbodithioate complexes of the general formula [M(4-MPipzcdt)_x(phen)_y]Y (M = Mn(II), Co(II), Zn(II); 4-MPipzcdt = 4-methylpiperazine-1-carbodithioate; phen = 1,10-phenanthroline; x = 1 and y = 2 when Y = Cl; x = 2 and y = 1 when Y = nil) were synthesized and screened for their antimicrobial activity against Candida albicans, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Enterococcus faecalis by disk diffusion method. All the complexes exhibited prominent antimicrobial activity against tested pathogenic strains with the MIC values in the range <8-512 gmL^-1. The complexes [Mn(4-MPipzcdt)₂(phen)] and [Co(4-MPipzcdt)(phen)₂]Cl inhibited the growth of Candida albicans at a concentration as low as 8 µgmL^-1. The complexes were also evaluated for their toxicity towards human transformed rhabdomyosarcoma cells (RD cells). Moderate cell viability of the RD cells was exhibited against the metal complexes.

Vaginal delivery of protein drugs in rats by gene-transformed Lactococcus lactis

A probiotic bacterium, Lactococcus lactis subsp. lactis (L. lactis) transformed with plasmid ss80, which made it capable of synthesizing and secreting β-lactamase, a 29 kDa protein, was used to deliver β-lactamase via vaginal route. The vaginal absorption of β-lactamase in rats was studied when delivered by this L. lactis system and compared to the β-lactamase solution with or without the untransformed L. lactis. The vaginal administration of 1.2 × 10(7), 3 × 10(7), and 8 × 10(7) colony forming units (cfu) of L. lactis resulted in the amount absorbed of 77, 194, and 216 mU, with the respective doses. C(max), mean retention time and mean absorption time of β-lactamase were also increased with the increase in the cfu of L. lactis administered. These results have demonstrated that L. lactis can significantly increase (p < 0.01) the β-lactamase vaginal absorption as compared to the β-lactamase solution, which is probably due to the adhesion of L. lactis to and continuous synthesis and delivery of β-lactamase directly to the vaginal mucosa. In conclusion, transformed normal flora may be an efficient method to deliver protein drugs through the vaginal route.

Delivery of TEM β-lactamase by gene-transformed Lactococcus lactis subsp. lactis through cervical cell monolayer

Lactococcus lactis subsp. lactis transformed with Plasmid ss80 (encoding the production and secretion of TEM beta-lactamase) was used for the delivery of beta-lactamase through the C-33A (cervix cell) monolayer. The viability of the cell monolayers co-cultured with L. lactis was examined by the trypan blue exclusion method. The integrity of the monolayers was monitored by measuring the transport of mannitol and propranolol as well as the transepithelial electrical resistance. The transport rate of beta-lactamase through C-33A monolayer was increased by four- and nine-folds (p < 0.05) at the first hour by the transformed L. lactis compared to the free solution with or without presence of the untransformed L. lactis, respectively. This increase was gradually diminished after the 1st hour: it became 30 and 50% (p < 0.05) at 10 h. The presence of the untransformed L. lactis with free solution delivery also increased the transport rate by 100% at 1 h (p < 0.05) and 15% at 10h (p>0.05). The increase in transport rate by the transformed L. lactis is most probably due to the concentrate of beta-lactamase on C-33A monolayer. When co-cultured with the L. lactis, the C-33A cell viability and the monolayer TEER remained steady for 10 h. The presence of L. lactis did not change the transport of propranolol and mannitol through the monolayers. In conclusion, the transformed L. lactis significantly (p < 0.05) increased the transport of beta-lactamase through the cervical monolayers, indicating probiotic bacteria delivery may be a promising approach for protein delivery through the vagina.

Oral delivery of beta-lactamase by Lactococcus lactis subsp. lactis transformed with Plasmid ss80

The objective was to use normal flora to deliver protein/peptide drugs orally. A probiotic bacterium, Lactococcus lactis subsp. lactis (L. lactis) transformed with Plasmid ss80, which made it able to synthesize and secrete beta-lactamase, a 29 kDa protein, was used as the delivery system for beta-lactamase. Oral absorption of beta-lactamase in rats when delivered by this L. lactis system was investigated. The oral bioavailability of beta-lactamase delivered by 3x10(7) of the L. lactis was equivalent to 209 mU of i.v. dose, and the estimated relative bioavailability was 16.7%. When delivered by beta-lactamase free solution form, the relative oral bioavailability was 4.7%, which increased to 6.0% when co-administered with 3x10(7) of the untransformed L. lactis. The results demonstrated that the L. lactis significantly increased the beta-lactamase oral bioavailability by 2-3-folds (p<0.01), the mean residence time (MRT) by 3-4 times (p<0.01), and the mean absorption time (MAT) by 6-14 times (p<0.01), as compared to the free solution form with/without the untransformed L. lactis. In conclusion, the L. lactis is more efficient in delivering beta-lactamase orally compared with the free solution form. It also provides a sustained delivery mechanism for beta-lactamase. Gene-transformed normal flora may be used as an efficient and sustained delivery system for protein drugs through oral route.

Normal flora: living vehicles for non-invasive protein drug delivery

Feasibility to use probiotic bacteria as a living protein delivery system through oral route was assessed in vitro. Lactococcus lactis transformed with a plasmid to express and secret beta-lactamase was used to deliver beta-lactamase through Caco-2 monolayer, an intestine epithelium. Transport of beta-lactamase through Caco-2 monolayer was carried out in the transwells. The viability and integrity of the cell monolayers co-cultured with L. lactis was examined by trypan blue exclusion method and by measuring the transport of mannitol and propranolol as well as the transepithelial electrical resistance (TEER). Results show that it is feasible to use cell culture technique to evaluate the drug delivery by normal flora. The transport rate of beta-lactamase when delivered by L. lactis was 2.0 +/- 0.1 x 10(-2)h(-1) (n = 9) and through free solution form was 1.0 +/- 0.1 x 10(-2)h-1. When co-cultured with L. lactis, Caco-2 cell viability decreased to 98, 96, and 94% at 6, 8, and 10h, respectively. Transport of mannitol through Caco-2 cell monolayer was significantly increased and the transport of propranolol through Caco-2 cell monolayer was significantly decreased in the presence of L. lactis. Increase in the amount of protein delivered is probably due to the concentrate of the protein by L. lactis on the monolayer (absorption surface) and the opening of the tight junction of Caco-2 monolayer by L. lactis.

Remnant model of renal failure in the dog: avoidance of second surgery by chemical nephrectomy

Experimental chronic renal failure in the dog is usually studied by a two-step surgical procedure. However, it is becoming increasingly difficult, due to animal welfare concerns, to get permission for such procedures in Canada. We describe a method for obviating the need for second surgery by injecting absolute alcohol into a renal artery, which leads to immediate functional nephrectomy.