Ondansetron oral spray (Zensana) versus ondansetron oral tablets in a randomized, bioavailability study in adult subjects

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Background: Zensana ondansetron oral spray (ZSN) is the first oral spray 5-HT3 antagonist to deliver ondansetron, the most commonly prescribed anti-emetic for chemotherapy induced nausea and vomiting (CINV) through the oral cavity. ZSN achieves therapeutic drug levels by delivering small droplets of concentrated drug solution over the oral mucosa, which has a rich blood supply and has been shown to be an alternative drug delivery route. ZSN may offer certain advantages to patients experiencing CINV who have difficulty swallowing and holding down pills. Methods: This was a randomized, crossover, pharmacokinetic (PK) study where ZSN, administered as 4mg, 8mg, 12mg, and 8mg with a 30-sec hold before swallowing was evaluated in healthy subjects against an 8mg ondasetron (Zofran [ZFR]) tablet (reference). Treatments were separated by 48 hrs. PK samples were measured during the 24 hrs after dosing and were assayed using LC/MS/MS techniques. PK parameters were analyzed using a cross-over ANOVA model. Two treatments were concluded bioequivalent if the 90% CI of the geometric mean ratios for ln-transformed Cmax, AUC0-t, and AUC0-inf fell between the FDA guideline of 80% to 125%. Results: Thirty-two subjects (17 women, 15 men) received each of the 5 treatments, except for one man who did not receive the 12mg dose. The geometric mean ratios and the 90% CI for Cmax, AUC0-t, and AUC0-inf respectively, for each pair of treatments were as follows: ZSN 4mg vs 8mg tablet (TAB): 41%(39–43%); 45%(43–47%), and 47%(45–49%); ZSN 8mg vs 8mg TAB: 87%(83–91%), 98%(94–102%), and 99%(94–103%); ZSN 12mg vs 8mg TAB: 145%(138–152%), 157%(150–164%), and 157%(150–164%); and ZSN 8mg with a 30 sec hold vs 8mg TAB: 86%(82–90%), 99%(94–103%), and 99%(95–104%). There were no serious or unexpected adverse events (AE) and the safety profile was similar across all treatments. The most commonly reported AEs were constipation (11/32[34%]), headache (10/32[31%]), and dizziness (5/32[16%]) which were mild to moderate in severity. Conclusions: ZSN 8mg falls within the FDA criteria for bioequivalence, and is bioequivalent to an 8mg ZFR tablet. ZSN 4, 8, or 12mg has a similar safety profile as a ZFR 8 mg tablet.

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Febuxostat (TMX-67), a novel, non-purine, selective inhibitor of xanthine oxidase, is safe and decreases serum urate in healthy volunteers

In order to evaluate the safety, pharmacological properties, and urate-lowering efficacy of febuxostat, a non-purine, selective inhibitor of xanthine oxidase, a Phase 1, 2-week, multiple-dose, placebo-controlled, dose-escalation study was conducted in 154 healthy adults of both sexes. Daily febuxostat doses in the range 10 mg to 120 mg resulted in proportional mean serum urate reductions ranging from 25% to 70% and in proportional increases in maximum febuxostat plasma concentrations and area under plasma concentration versus time curves. Accompanying the hypouricemic effect were increases in serum xanthine concentrations, decreases in urinary uric acid excretion, and increases in urinary xanthine and hypoxanthine excretion, confirming inhibition of xanthine oxidase activity by febuxostat. Hepatic conjugation and oxidative metabolism were the major pathways of elimination of febuxostat from the body, and renal elimination did not appear to play a significant role. Although not uncommon, adverse events were mild and self-limited, and no deaths or serious adverse events were observed. Febuxostat is a safe and potent hypouricemic agent in healthy humans.

Pharmacokinetics and pharmacodynamics of peldesine (BCX-34), a purine nucleoside phosphorylase inhibitor, following single and multiple oral doses in healthy volunteers

The pharmacokinetic parameters of peldesine (BCX-34) were investigated after single and multiple oral doses in two groups of healthy adult volunteers. The pharmacodynamic elevation of endogenous inosine and 2'-deoxyguanosine was simultaneously monitored. The first group of 8 subjects received an intravenous dose (18 mg/m2) and five oral doses (30, 63, 108, 144, and 192 mg/m2) of drug. A second group of 12 subjects received 160 mg/m2 in four and in six divided doses orally. Serial blood samples and total urine outputs were collected during dosing and for at least 24 hours after the last dose was administered. One set of samples was analyzed using high-pressure liquid chromatography/ultraviolet (LC/UV) methods, validated for intact drug in human plasma and urine samples. Another set of samples was analyzed for the biomarkers, inosine and 2'-deoxyguanosine, using high-pressure LC with either mass spectrometry (MS) or electrochemical detection (EC) methods. The pharmacokinetic parameters of inosine and 2'-deoxyguanosine were calculated using noncompartmental methods and correlated against the pharmacokinetic parameters of BCX-34. For the single-dose study, the results exhibited linear pharmacokinetics over the dose range from 30 to 144 mg/m2. The calculated terminal half-life was 3.5 +/- 1.0 h, and the absolute bioavailability of the oral formulation was approximately 51%. Analysis of urine in the first 24 hours of collection accounted for approximately 82% of the absorbed intact drug. Evaluation of the multiple-dose pharmacokinetics indicated that steady-state blood concentrations were achieved by 24 hours when the drug was administered four or six times a day. A drug dose-related elevation of plasma 2'-deoxyguanosine was observed. This phenomenon was not seen with plasma inosine levels. However, analysis of urine samples showed an increase in inosine output with an increase in the drug dose. The calculated terminal half-life of inosine and 2'-deoxyguanosine was 15.3 +/- 1.8 h and 1.3 +/- 0.1 h, respectively.

Oral delivery of anticoagulant doses of heparin. A randomized, double-blind, controlled study in humans

BACKGROUND

Parenteral heparin is the anticoagulant of choice in hospitalized patients. Continued anticoagulation is achieved by subcutaneous administration of low-molecular-weight heparin or with an orally active anticoagulant such as warfarin. An oral heparin formulation would avoid the inconvenience of subcutaneous injection and the unfavorable drug interactions and adverse events associated with warfarin. A candidate delivery agent, sodium N-[8(-2-hydroxybenzoyl)amino]caprylate (SNAC), was evaluated with escalating oral heparin doses in a randomized, double-blind, controlled clinical study for safety, tolerability, and effects on indexes of anticoagulation.

METHODS AND RESULTS

Increases in activated partial thromboplastin time (aPTT), anti-factors IIa and Xa, and tissue factor pathway inhibitor (TFPI) concentrations were detected when normal volunteers were dosed with 10.5 g SNAC/20000 IU heparin by gavage in some subjects. For the entire group, 30000 IU SNAC and heparin elevated TFPI from 74.9+/-7.6 to 254.2+/-12.3 mg/mL (P<0.001) 1 hour after dosing (P<0.001). Similar changes occurred in anti-factor IIa and anti-factor Xa. aPTT rose from 28+/-0.5 to 42.2+/-6.3 seconds 2 hours after dosing (P<0.01). No significant changes in vital signs, physical examination, ECGs, or clinical laboratory values were observed. Neither 30000 IU heparin alone nor 10.5 g SNAC alone altered the hemostatic parameters. Emesis was associated with 10.5 g SNAC. A taste-masked preparation of SNAC 2.25 g was administered orally with heparin 30000 to 150000 IU. Both aPTT and anti-factor Xa increased with escalating doses of heparin. This preparation was well tolerated. Conclusions-Heparin, administered orally in combination with the delivery agent SNAC, produces significant elevations in 4 indexes of anticoagulant effect in healthy human volunteers. These results establish the feasibility of oral delivery of anticoagulant doses of heparin in humans and may have broader implications for the absorption of macromolecules.

Effect of increasing gastric pH with famotidine on the absorption and oral pharmacokinetics of the inotropic agent vesnarinone

The effect of famotidine, an H2 receptor blocker, on the oral absorption and pharmacokinetics of the novel agent vesnarinone was investigated after oral administration of 60 mg vesnarinone with and without pretreatment with intravenous famotidine. The single-blind, randomized, two-way crossover study was conducted in 12 volunteers, with a washout period of 7 days between the two treatments. A pH monitor was used to ensure that gastric pH of the subjects was < or = 3 in the absence of and > or = 5 in the presence of famotidine. A significant decrease in maximum concentration (Cmax) and increase in time to Cmax (tmax) was observed for vesnarinone during treatment with famotidine, whereas area under the concentration-time curve (AUC) was similar for both treatments. The physicochemical properties of the drug support the above observations. Therefore, therapies that increase gastric pH will affect the rate but not the extent of absorption of vesnarinone or the safety or efficacy profile of vesnarinone.

Pramlintide: a human amylin analogue reduced postprandial plasma glucose, insulin, and C-peptide concentrations in patients with type 2 diabetes

In order to determine the influence of a 5 h infusion of pramlintide compared to placebo on postprandial glucose, lactate, insulin, and C-peptide concentrations in patients with Type 2 diabetes, a single-blind, randomized, cross-over study was conducted in 24 patients; 12 treated with exogenous insulin and 12 managed with diet and/or oral hypoglycaemic agents. One hour after initiation of infusion, patients consumed a Sustacal test meal. The protocol was repeated on the following day with each patient receiving the alternate study medication. Pramlintide infusion in the insulin-treated patients resulted in statistically significant reductions in mean glucose, insulin, C-peptide, and lactate concentrations during the 4-h period after the Sustacal test meal. Pramlintide infusion also resulted in significant reductions of mean insulin, C-peptide, and lactate concentrations, but not glucose concentrations, in the patients treated with diet and/or oral hypoglycaemic agents. Within this latter group, reduction in postprandial glucose concentrations in individual patients correlated with glycated haemoglobin values. These results suggest that administration of pramlintide may improve glycaemic control in patients with Type 2 diabetes treated with insulin or poorly controlled on diet and/or oral hypoglycaemic agents.

Pharmacokinetic comparison of a once-daily and twice-daily theophylline delivery system

The steady-state pharmacokinetics of a formulation of a 24-hour extended-release theophylline preparation (Uni-Dur) were compared with a twice-daily formulation (Theo-Dur) in healthy volunteers. Eighteen healthy, adult, male volunteers received both treatments (600-mg dose of Uni-Dur every morning for 5 doses or 300 mg every 12 hours for 10 doses of Theo-Dur) in a randomized, two-way crossover design with no washout period between treatments. Blood samples were collected just before doses 3, 4, and 5 of Uni-Dur and before doses 5, 7, and 9 of Theo-Dur, as well as at 2-hour intervals for 24 hours following doses 5 of Uni-Dur and doses 9 and 10 of Theo-Dur. The mean serum theophylline concentration-time curves were similar for both formulations from 2 to 18 hours postdose, and the maximum serum theophylline concentrations were comparable (7.66 micrograms/mL for Uni-Dur compared with 7.78 micrograms/mL for Theo-Dur). Fluctuations in serum theophylline concentrations were greater with Uni-Dur (139 +/- 85% compared with 72 +/- 25% normalized to trough serum concentrations; 77 +/- 22% compared with 53 +/- 13% normalized to average steady-state serum concentrations). Based on the area under the curves, the extent of absorption of Uni-Dur was 91.42 +/- 14.24% of Theo-Dur. These findings suggest that the clinical response in patients treated with once-daily Uni-Dur may be equivalent to Theo-Dur given every 12 hours. Furthermore, because of the similar serum concentration over time profiles of the two formulations, it is unlikely that additional monitoring of serum levels during a conversion will be necessary.

Acadesine (AICA-riboside): disposition and metabolism of an adenosine-regulating agent

Acadesine (AICA-riboside) is a purine nucleoside analog with anti-ischemic properties that is currently being studied (Phase 3) for the prevention of adverse cardiovascular outcomes in patients undergoing coronary artery bypass graft (CABG) surgery. The safety, tolerance, and pharmacokinetics of the drug have previously been reported in this journal (J Clin Pharmacol 1991; 31:342-347). Recently, the authors studied the disposition and metabolism of acadesine in healthy males (n = 4) after a 15-minute intravenous infusion of 25 mg/kg of 2-14C-acadesine. The postinfusion total 14C concentrations in plasma declined in a multiexponential manner, and the terminal phase had an apparent t1/2 of about 1 week. Intact acadesine was only measurable for 2 hours after infusion. Total plasma clearance was 2.2 +/- 0.2 L/hour/kg, the acadesine blood/plasma ratio was unity, and plasma protein binding was negligible (approximately 1%). Uric acid, the end product of purine metabolism in humans, was the major metabolite of acadesine in plasma and accounted for all of the total, plasma 14C at 6 hours after infusion. In whole blood, acadesine 5'-monophosphate was present in the red blood cells, and the nucleotide represented 30% of the total blood 14C at the end of the infusion. The nucleotide was confined to the RBCs and was not present in plasma. Urine and fecal recoveries over 2 weeks accounted for 48% of the total 14C dose, with 44% excreted in urine and 4% in feces. Only 5% of the dose was excreted in urine as intact acadesine. Uric acid was the major metabolite in urine together with small amounts of hypoxanthine.(ABSTRACT TRUNCATED AT 250 WORDS)