Discussion comments on 'On moments of the unit Lindley distribution'.

In a note about the paper titled 'On the one parameter unit-Lindley distribution and its associated regression model for proportion data', Mazucheli et al. [J. Appl. Stat. 46 (2019), pp. 700-714] and Nadarajah and Chan [On moments of the unit Lindley distribution, J. Appl. Stat. (under review)] claim that 'The expressions given for the moments and incomplete moments are not correct and not in closed form'. While we agree that they are not in closed form and observe a typo in the expressions for µ k ' and T k ( t ) , k = 1 , … , the expressions for µ 1 ' , µ 2 ' , µ 3 ' and µ 4 ' are, however, entirely correct.

The unit-Weibull distribution as an alternative to the Kumaraswamy distribution for the modeling of quantiles conditional on covariates.

The Beta distribution is the standard model for quantifying the influence of covariates on the mean of a response variable on the unit interval. However, this well-known distribution is no longer useful when we are interested in quantifying the influence of such covariates on the quantiles of the response variable. Unlike Beta, the Kumaraswamy distribution has a closed-form expression for its quantile and can be useful for the modeling of quantiles in the absence/presence of covariates. As an alternative to the Kumaraswamy distribution for the modeling of quantiles, in this paper the unit-Weibull distribution was considered. This distribution was obtained by the transformation of a random variable with Weibull distribution. The same transformation applied to a random variable with Exponentiated Exponential distribution generates the Kumaraswamy distribution. The suitability of our proposal was demonstrated to model quantiles, conditional on covariates, with two simulated examples and three real applications with datasets from health, accounting and social science. For such data sets, the obtained fits of the proposed regression model were compared with those provided by the Beta and Kumaraswamy regression models.

Comparative bioavailability study of two phenoxymethylpenicillin potassium tablet formulations in healthy volunteers.

OBJECTIVE: The aim of this study was to evaluate the performance of 2 phenoxymethylpenicillin 500,000 UI tablet formulations in healthy human volunteers. MATERIAL AND METHODS: The study was conducted using an open, randomized crossover design with a 7-day washout interval. A single dose of each formulation was administered to 26 healthy volunteers as assessed by clinical and laboratory test evaluations. The plasma samples were obtained over an 8-h interval and phenoxymethylpenicillin concentrations were quantified by a suitable and validated HPLC-UV method with detection at 220 nm. Systolic and diastolic blood pressure and pulse rate measurement were taken pre dose and at intervals up to 8 h. RESULTS: Tolerance of both products was adequate. The mean of Meracilina/Pen-Ve-Oral 500,000 UI% geometric mean was 99.89% for AUC0-t, 100.86% for AUC0-infinity and 101.11% for Cmax. The 90% confidence intervals were 94.62 - 105.46%, 95.22 - 106.83% and 98.61 - 103.87%, respectively. The mean recovery of phenoxymethylpenicillin was 94.8%, while the retention time observed for phenoxymethylpenicillin and phenytoin (internal standard) was 4 and 10 min, respectively. The limit of quantification was 0.10 mg/l. CONCLUSION: Since the 90% CI for AUC0-t, AUC0-infinity and Cmax ratios were all within the 80 - 125% interval proposed by the US FDA and accepted by ANVISA, it was concluded that the Meracilina formulation (manufactured by AchA(c) S.A.) is bioequivalent to Pen-Ve-Oral (manufactured by Eurofarma) for both the rate and the extent of bioavailability.

Digoxin bioequivalence study: determination in human plasma by microparticle enzyme immunoassay.

OBJECTIVE: In this study a bioanalytical method for digoxin quantification was developed using Abbott AxSYM Digoxin II with fluorescence detection to assess the bioequivalence of two digoxin tablet formulations (Digox 0.25 mg tablet from Pharlab Ind. Ltd., Brazil as test formulation and Digoxin 0.25 mg tablet from Laboratório Glaxo SmithKline, Brazil as reference formulation). MATERIAL AND METHODS: 30 healthy volunteers (both sexes) received a single oral dose of digoxin in an open, randomized, two-period crossover study with a seven half-life washout interval of at least (21 days). Plasma samples were obtained over a 288-h interval after each oral administration of digoxin. The present method utilizes microenzyme particle immunoassay technology, in which the digoxin in the sample binds to anti-digoxin-coated microparticles and after separation; digoxin-alkaline phosphatase conjugate binds to the available sites remaining. Digoxin concentrations are calculated from the fluorescent products generated as a result of substrate (4-methylumbelliferyl) passage through the matrix cell. RESULTS: The method was shown to be specific and sensitive with good accuracy and precision. The geometric mean and 90% confidence intervals (CI) for the Digox/Digoxin ratio were 107.62% (96.71 - 119.80%) for AUC0-t, 97.15% (80.54 - 117.19%) for AUC0-inf, and 91.23% (83.55 - 99.62%) for Cmax. CONCLUSION: Since the 90% CI for the parameters were all within the 80 - 125% interval proposed by the US Food and Drug Administration Agency, the two formulations were considered bioequivalent in terms of rate and extent of absorption.