An Isolated and Deeply Divergent Hynobius Species from Fujian, China

It is important to describe lineages before they go extinct, as we can only protect what we know. This is especially important in the case of microendemic species likely to be relict populations, such as Hynobius salamanders in southern China. Here, we unexpectedly sampled Hynobius individuals in Fujian province, China, and then worked on determining their taxonomic status. We describe Hynobius bambusicolus sp. nov. based on molecular and morphological data. The lineage is deeply divergent and clusters with the other southern Chinese Hynobius species based on the concatenated mtDNA gene fragments (>1500 bp), being the sister group to H. amjiensis based on the COI gene fragment, despite their geographic distance. In terms of morphology, the species can be identified through discrete characters enabling identification in the field by eye, an unusual convenience in Hynobius species. In addition, we noted some interesting life history traits in the species, such as vocalization and cannibalism. The species is likely to be incredibly rare, over a massively restricted distribution, fitting the definition of Critically Endangered following several lines of criteria and categories of the IUCN Red List of Threatened Species.

Coexisting good neighbours: acoustic and calling microhabitat niche partitioning in two elusive syntopic species of balloon frogs, Uperodon systoma and U. globulosus (Anura: Microhylidae) and potential of individual vocal signatures

Background

Most amphibians use a repertoire of acoustic signals to propagate signals in social contexts. The description of these repertoires provides a key towards the understanding of the behaviour of individuals and the evolutionary functions of calls. Here, we assessed the variations in advertisement calls within and between two fossorial sympatric species, Uperodon systoma and Uperodon globulosus, that share their breeding season and breeding sites. For each species, we applied Beecher’s index of total information capacity (HS) for the individual vocal signature, determined the difference in call properties and demonstrated the segregation in the calling microhabitat niche between the two species.

Results

Our results demonstrated that the advertisement calls of U. systoma are pulsatile with a call rate of 3.00 ± 0.97 calls per second while those of U. globulosus are not pulsatile with a lower call rate of 0.53 ± 0.22 calls per second. For both species, the variations in call properties among individuals was higher than that within individual, a pattern consistent with that of other fossorial anurans. The body condition and air temperature did not significantly impact the call properties of either species. The outcome of the Beecher’s index (HS) showed that the calls of U. systoma can be used to identify 14 different individuals and the calls of U. globulosus can be used to identify 26 different individuals. The statistical analyses on the advertisement call of the two species showed a significant difference in the temporal properties as the call duration, and fall time and rise time were significantly different between the two species. Lastly, we successfully demonstrated that there is a clear segregation in calling site microhabitat between the two species, where U. globulosus calls floating close to the bank of the waterbody while U. systoma calls floating further away from the bank.

Conclusion

This study highlights the potential for pre-mating isolation, character displacement and assortative mating in two syntopic fossorial anurans, leading to association between acoustic, calling microhabitat niche and body index divergence as important behavioural and ecological traits.

A phylogeographical framework for Zhangixalus gliding frogs, with insight on their plasticity of nesting behaviour

Old World tree frogs from the family Rhacophoridae, one of the most species-rich groups of amphibians worldwide, are becoming a model in ecological and evolutionary research, notably for their tremendous diversity of breeding systems. In this study, we provide the most comprehensive temporally and spatially explicit phylogeographical framework for the tropical neo-genus Zhangixalus, with a specific focus on the evolution of inter- and intraspecific polymorphism in their egg-laying strategies. We combined ~500 sequences spanning ~4 kb of mitochondrial genes, representative of nearly all known Zhangixalus species from 373 localities. We recovered a robust timetree featuring ~60 phylogeographical lineages assigned to 36 taxa, illustrating a vast under-appreciation of the diversity of the genus. Patterns of diversification were intimately linked to climatic trends since the Mid-Miocene, leading to a remarkable biogeographical scenario for the onset of Taiwanese diversity. Finally, in contrast to the macro-evolution of conserved breeding strategies in rhacophorids, the striking variation of nesting behaviour documented across Zhangixalus species, whereby foamy egg nests are alternatively fossorial, deposited on the edge of the water or suspended on the overhanging vegetation, seems to have evolved rapidly from arboreal ancestors in all major clades, implying micro-evolutionary processes and/or phenotypic plasticity.

Distribution status of the Western Burrowing Frog, Sphaerotheca pashchima in India

In a recent study, Hortal et al. (2015) recognized seven shortfalls of knowledge that hamper our understanding of biodiversity. Three of these are of particular importance for drawing conservation strategies for ecological indicator species, among which we can count the amphibians (Simon et al. 2011): the Linnean shortfall describes 'the knowledge incongruity between the described species and the remaining species yet to be described' (Brown Lomolino 1998); the Wallacean shortfall defines 'paucity of knowledge about the actual distribution range of the species' (Lomolino 2004); and the Darwinian shortfall refers to 'lack of knowledge about the tree of life and evolution of lineages, species and traits' (Diniz-Filho et al. 2013).

Identification of anuran species diversity of the Panna Tiger Reserve, Central India, using an integrated approach

We present a comprehensive inventory of amphibians from Panna Tiger Reserve in Madhya Pradesh based on morphological, molecular and bioacoustic data. Representatives of 15 anuran species were collected, corresponding to roughly four fifths of the known amphibian species of Madhya Pradesh. The main results of this study are: (1) Description of advertisement calls of eleven species, including the first-time description of advertisement calls of Sphaerotheca pashchima. (2) Identification of cryptic species using acoustic and molecular techniques. (3) Five new significant range extensions and new state records. (4) Description of geographical variation in call properties in three anuran species. This study also provides morphological descriptions with ecological and natural history notes for each species that may be useful in management planning for amphibian conservation in Panna Tiger Reserve.

<b>An annotated checklist of the herpetofauna of the Rashtrapati Bhawan Estates, New Delhi, India</b>

Rashtrapati Bhavan Estates is a large semi-natural area comprising significant patches of secondary forest, cultivation, wetlands and parks in the heart of Delhi, the capital city of India.  An inventory of herpetofauna was undertaken from May 15 to July 31, 2015, which revealed four species of amphibians and eight of reptiles.  One reptilian species—Striped Keelback—was a new record for the Delhi region.  In addition, secondary records of the presence of five snake species were obtained.  Given the paucity of published data on natural history of the national capital, this annotated species checklist assumes importance and will be of use for urban planning and conservation. 

Emerging trends in transplantation of inherited metabolic diseases

Allogeneic hematopoietic stem cell transplantation (HSCT) can prolong life and improve its quality in patients with inherited metabolic diseases. HSCT offers a permanent source of enzyme replacement therapy and also might mediate nonhematopoietic cell regeneration or repair. Unrelated cord blood is an exciting newer graft source for treatment of patients with these fatal disorders, providing increased access to donors and significant clinical efficacy, particularly when transplantation is performed in early stages. Pre-transplant performance status is highly predictive of overall survival.

Cytomegalovirus ventriculoencephalitis in a bone marrow transplant recipient receiving antiviral maintenance: clinical and molecular evidence of drug resistance

We describe a case of CMV ventriculoencephalitis in a severely immunocompromised bone marrow transplant recipient who was receiving combination therapy with ganciclovir and foscarnet for treatment of viremia and retinitis. Analysis of sequential viral isolates recovered from the patient's cerebrospinal fluid suggested that disease developed because of the presence of viral resistance and, possibly, low tissue penetration of antiviral agents.

Increased 5alpha-reductase and normal 11beta-hydroxysteroid dehydrogenase metabolism of C19 and C21 steroids in a young population with polycystic ovarian syndrome

OBJECTIVE

To test the hypothesis that 5alpha-reductase (5alphaR) and 11beta-hydroxysteroid dehydrogenase (11beta-HSD) activity are increased in adolescent and young-adult women with PCOS and that an altered regulation of the hypothalamic-pituitary-adrenal (HPA) axis occurred in these subjects.

DESIGN

Prospective non-randomized study in an academic research environment.

PATIENTS

Eleven women, aged 14 to 25 years, were studied who were at least one year post-menarche and who had a diagnosis of PCOS based on a history of oligomenorrhea and elevated total and or free serum testosterone.

INTERVENTION

24-Hour urinary metabolites were assessed in nine subjects and five underwent stimulation with ovine corticotropin releasing factor (oCRF).

OUTCOME MEASURES

C19 and C21 steroid urinary metabolite 5-alpha/5-beta pairs, 11-oxo/11-hydroxy products and the ratio of the total 5-alpha/5-beta reduced and 11-oxo/11-hydroxy products were compared to values in control women. Urinary cortisol (F) (sum of conjugated and free, and free F) and total F metabolites (the sum of THE, THF, 5alpha-THF, cortolones, and cortols) were determined. A 1 microg/kg oCRF stimulation test was performed with timed samples determined for plasma ACTH and serum F levels.

RESULT

The 24-hour total and free urinary F were not different from control. However, the total F metabolites were markedly elevated (7922+/-2666 vs 5418+/-1549 microg/24 h, p<0.01). A marked increase in the total 5-alpha reduced C19 and C21 metabolites was observed in the PCOS population vs control (5084+/-1977 vs 2681+/-1188 microg/24 h, p<0.01). The total urinary 11-oxo/11-hydroxy metabolite ratio was not different, p=0.23. The basal values and response of both ACTH and F to oCRF stimulation were not different from those of controls.

CONCLUSION

There is a marked increase in 5alphaR metabolism of both C19 and C21 steroids in younger women with PCOS.

The probability of HLA-C matching between patient and unrelated donor at the molecular level: estimations based on the linkage disequilibrium between DNA typed HLA-B and HLA-C alleles

BACKGROUND

Recent evidence suggests a more significant role of HLA-C as a target of alloreactions after bone marrow transplantation than previously suspected. Although linkage disequilibrium (LD) between HLA-B and -C serogroups is well documented, the level of LD at the allelic level is not known. In this study, we determine the LD between HLA-B and -C alleles and estimate the probability of molecular HLA-C matching between unrelated individuals who match for both HLA-B alleles.

METHODS

The study included 727 haplotypes from 849 individuals who were HLA-A, -B, -C and -DRB1 typed by high-resolution PCR-SSOP technique. Zelterman's statistic was used to test for global LD between HLA loci. LD between specific HLA-B and -C allelic combinations was calculated from their observed and expected frequencies in the study haplotypes. The probability of HLA-C matching for specific HLA-B allele was estimated from contingency table generated from the HLA-B and -C haplotypes.

RESULTS

HLA-C was found to exist in LD with HLA-A and -B, as well as -DRB1, loci; however, it was strongest between HLA-B and -C loci. A marked variability in the level of LD between specific HLA-B and -C alleles was noticed. A strong LD was seen in some allele pairs like B*0702-C*w0702, B*3501-Cw*0401, and B*0801-Cw*0701. The overall estimated probability of HLA-C matching between unrelated individuals that match for both HLA-B alleles is 42.25%. For 237 (72.9%) of 325 combinations involving the 25 commonest HLA-B alleles, the estimated probability that the HLA-B-matched unrelated individuals will match for both HLA-C alleles is less than 50%. In addition, a 100% probability of matching for both HLA-C alleles is expected only if both individuals bear either B*0801/ B*0801 or B*4901/B*4901 or B*0801/B*4901. Probability tables for common alleles are presented.

CONCLUSIONS

We conclude that, despite matching for both HLA-B alleles by high resolution DNA typing and the presence of a strong LD between HLA-B and HLA-C loci, unrelated individuals are more likely to mismatch rather than match for one or both HLA-C alleles.

HLA-C disparity between patients and unrelated donors matched for HLA-A, -B, and -DRB1 alleles: impact of serological vs. DNA typing for HLA-A and -B loci

High incidences of graft failure, graft-vs.-host disease (GVHD), and serious infections following unrelated donor (URD) marrow transplantation, despite apparent human leukocyte antigen (HLA) identity, may reflect the presence of molecular disparities, including those for HLA-C alleles between the patient and the URD. The level of these disparities could be significant, because as many as 42 alleles are currently known for HLA-C locus. We studied 84 patients and 251 potential URDs to evaluate 1) the extent of HLA-C disparity between the patient and the URD identified by serology for HLA-A and -B and by DNA typing for -DRB1 and 2) the level of HLA-C disparity between patients and URDs matched by high-resolution DNA typing for HLA-A, -B, and -DRB1. The DNA typing was performed at the Memorial Sloan Kettering Cancer Center, and the serotyping was provided by the registries. Of 251 URDs matched by HLA-A and -B serology and -DRB1 (sA_sB_dnaDRB1 ); 94, 75, and 82 were 6/6, 5/6, and 4/6 matches, respectively. Of 94 sA_sB_dnaDRB1 6/6 URDs, 51 (54.3%) were matched for both HLA-C alleles. In contrast, 31 (41.3%) 5/6 (p=0.12) and 15 (18.3%) 4/6 (p < 0.01) sA_sB_dnaDRB1 URDs were matched for both HLA-C alleles. Following DNA typing for HLA-A and -B, 52 (55.3%) of 94 6/6, 30 (40%) of 75 5/6, and 25 (30.5%) of 82 4/6 sA_sB_dnaDRB1 URDs remained 6/6, 5/6, and 4/6 matches at the DNA level (dnaA_B_DRB1). HLA-C disparities continued to exist in the dnaA_B_DRB1 URD group. Of 54 dnaA_B_DRB1 6/6 URDs, 41 (75.9%) were matched for both HLA-C alleles. Only 45.3% of the 5/6 (p=0.01) and 22.2% of the 4/6 (p < 0.01) dnaA_B_DRB1 URDs were matched for both HLA-C alleles. In the 6/6 category, the frequency of HLA-C matching improved (75.9 vs. 54.3%; p=0.01) following DNA matching for HLA-A and -B. In comparison to mismatching for HLA-B locus, mismatching for either HLA-DRB1 or -A resulted in a lower odds ratio for HLA-C disparity. The presence of a common haplotype in the sA_sB_dnaDRBl (p=0.06) URD category improved the level of HLA-C matching. We identified alleles that are associated with high (B*1501, B*4402, B*5101, DRB1*0101, A*0201, A*1101, A*2301, and A*3201) or low (B*0702, B*0801, B*1302, B*3502, DRB1*0301, DRB1*1104, A*0101, A*3001, and A*6801) probability of HLA-C disparity. Overall, sA_sB_dnaDRB1 as well as dnaA_B_DRB1 matched URDs for non-Caucasian patients were more likely to have HLA-C disparity in comparison to the matched URDs of Caucasian patients. However, a high incidence of HLA-C disparities was identified even in the URDs for Caucasian patients. Whether the disparities demonstrated by this study contribute to the higher immunological complications noted following URD bone marrow transplantation is unclear. Outcome analysis and studies aimed at understanding the functional role of HLA-C may provide an answer.

DNA typing for HLA-A and HLA-B identifies disparities between patients and unrelated donors matched by HLA-A and HLA-B serology and HLA-DRB1

High incidences of graft failure and graft-versus-host disease in the recipients of bone marrow transplantations (BMT) from unrelated donors (URD) may reflect the existence of allelic disparities between the patient and the URD despite apparent HLA identity at HLA-A, HLA-B, and HLA-DRB1 loci. To identify the extent and pattern of allelic disparities at HLA-A and HLA-B loci, 128 patients and 484 potential URD were evaluated by DNA typing. DNA typing for HLA-A, HLA-B, and HLA-DRB1 was performed at Memorial Sloan Kettering Cancer Center. HLA-A and HLA-B serotyping on URD was provided by the registries. By original typing (serology for HLA-A and HLA-B; DNA typing for DRB1) 187, 164, and 133 URD were 6/6, 5/6, and 4/6 matches, respectively. Following DNA typing, however, only 52.9% of the originally 6/6 matched URD remained 6/6, while 38.5%, 7.5%, and 1.1% were found to be 5/6, 4/6, and 3/6 matches. The level of disparity was higher in the originally 5/6 (P <.01) and 4/6 (P <.01) matched URD. A higher level of disparity was seen for HLA-B as compared to HLA-A. In addition, a serotype related variation was also noticed. For example, 24.1% of HLA-A2 and 60.1% of HLA-B35 seromatched URD were genotypically disparate, but no disparities were seen for HLA-A1 and HLA-B8. A higher percentage of HLA-A (67. 4%) compared with HLA-B (35.4%) serologic homozygous URD remained genotypically homozygous (P =.01). The level of allelic disparity was lower (P <.01 for 6/6; P =.02 for 5/6) if the patient had one of the 15 most common haplotypes (A1B8DR3, A2B7DR15, A3B7DR15, etc) in comparison to the rest of the group. Outcome studies will answer the question whether these disparities are associated with a higher rate of immunological complications seen with URD-BMT.

TTP following ITP in an HIV-positive boy

PURPOSE

To report the previously undescribed development of thrombotic thrombocytopenic purpura (TTP) in a human immunodeficiency virus (HIV)-positive child and discuss the differential diagnosis.

PATIENT AND METHODS

Our patient was a 9-year-old boy with vertically acquired HIV infection and a previous history of immune thrombocytopenic purpura (ITP). Initial presentation, difficulty in diagnosis, clinical course, and subsequent outcome are described.

RESULTS

Rapid resolution of TTP following plasmapheresis was seen.

CONCLUSIONS

Recognition of this treatable though potentially fatal complication in severely ill HIV-infected children requires a high degree of suspicion in view of its diverse clinical manifestations. The long-term outcome may be relatively good.

Progressive glomerular toxicity of ifosfamide in children

Glomerular toxicity following ifosfamide (IFO) is not as well recognized as renal tubular damage. Following a case of ifosfamide-induced renal failure with histological evidence of glomerular changes, we undertook a retrospective study of all IFO-treated children to assess the extent and severity of its glomerular toxicity and to identify possible predisposing factors. Thirty-seven children with a follow-up of 6 months or more from the end of chemotherapy were studied. They were a median of 10.8 years old (range 3.25-18.5), had received a median of 54 g/m2 (range 9-135) of IFO, and had a median follow-up of 29 months (range 6-68). The criteria to identify glomerular dysfunction were raised plasma creatinine (Pc) values on two occasions or a low glomerular filtration rate (GFR) measured by Tc-99-DTPA clearance. Detailed assessment was carried out to identify other nephrotoxic influences in these children. Subjects in whom glomerular dysfunction could be causally linked to IFO were compared with the rest of the group for a variety of predisposing factors. Of eight children with glomerular dysfunction, two had other nephrotoxic influences and were excluded from further analysis. In six (17.1%) children, glomerular dysfunction appeared to be causally linked to IFO. Their median GFR was 61.9 ml/min/1.73 m2(range 33-85) and Pc was 123 mumol/l (range 85-216). Five of the six had normal glomerular function at the end of therapy and the raised Pc values were first noted 19, 21, 26, 29, and 36 months later. Children with glomerular toxicity had a significantly longer median follow-up (41.5 vs. 19 months; P = 0.04) than the rest of the group, suggesting late onset of this problem. They were older at the time of the study and had received nearly twice the dose of IFO, though the differences in age and dose did not reach statistical significance. The earliest signs of renal toxicity were seen in the index case, who had had prior nephrectomy. All affected children had coexistent and preceding tubular toxicity. The inadequacies of tests commonly used to assess glomerular function and the possibility of underestimation of dysfunction are discussed. Glomerular dysfunction following IFO is poorly recognized and evidence from this study of its later onset and progressive nature is a cause for concern. The index case is described with histological findings.

Allele assignment for HLA-A, -B, and -C genes to the Tenth International Histocompatibility Workshop cell lines

Development of DNA typing for Class I HLA alleles has lagged behind that of class II for a variety of technical reasons. Following the recognition of locus specific sequences in the first and the third intron, and acquiring the ability to amplify genomic DNA by intron-based PCR primer, we have devised DNA typing of class I alleles by SSOP and direct sequencing. In this study using these techniques we provide the allelic typing of HLA-A, -B, and -C genes for the B-lymphoblastoid reference cell lines from the Tenth International Histocompatibility Workshop. We also describe some common associations of the C alleles with HLA-A and HLA-B alleles.

Treatment of hyperkalaemia using intravenous and nebulised salbutamol

In 11 children (aged 5-18 years) with end stage chronic renal failure, the effect on plasma potassium of two doses of salbutamol (separated by two hours) given intravenously (4 micrograms/kg) and on a separate date, of salbutamol administered by nebuliser (2.5 mg if the child weighed below 25 kg, 5 mg if above) was observed. Within 30 minutes of the first dose, the mean plasma potassium concentration fell significantly by 0.87 and 0.61 mmol/l after intravenous and nebulised administration respectively. Sixty minutes after the second dose the plasma potassium was significantly reduced by a further 0.28 and 0.53 mmol/l respectively. There was a significant difference between the two methods of administration at 300 minutes after the first dose favouring nebulisation. No major side effects were observed. Nebulised salbutamol should be the first choice emergency treatment of hyperkalaemia.

Ifosfamide enantiomers: pharmacokinetics in children

Ifosfamide, like other oxazaphosphorine drugs, is chiral and there is some evidence, mainly from animal studies, of stereo-selective differences in metabolism, excretion and cytotoxic activity between the two enantiomers. The pharmacokinetics of racemic ifosfamide (RAC-IFO), R-ifosfamide (R-IFO) and S-ifosfamide (S-IFO) were studied in five children who received intravenous therapy with racemic ifosfamide on 3 consecutive days. The clearance of S-IFO was greater than that of R-IFO. The clearance value at the end of the infusion was faster than the respective rate measured at the beginning of or during the ifosfamide regimens in four children and, therefore, suggests autoinduction of elimination of both enantiomers.

Phenotypic differences in dextromethorphan metabolism

Polymorphic differences in dextromethorphan metabolism were observed in three studies conducted in a total of 44 subjects (of Dutch origin) administered 60 mg dextromethorphan hydrobromide as an OROS tablet. Mean plasma dextromethorphan (DM) concentrations after a single dose and at steady state were 4-75 times higher in the poor metabolizers (PM) relative to the extensive metabolizers (EM). Following a single dose, the mean areas under the plasma concentration-time curve (AUC, 0-24 hr) of DM, total dextrorphan (DR), and total 3-hydroxymorphinan (HM) were 6.9-fold higher, 17.4-fold lower, and 11-fold lower, respectively, for the PM than for the EM. Correspondingly, steady-state AUC values were 52.8 times higher, 6.7 times lower, and 3.3 times lower for DM, total DR, and total HM, respectively, for the PM relative to the EM. Drug/metabolite ratios (DMR) for amounts excreted in the urine of DR and HM indicated polymorphism in O-demethylation of DM since DMR for PM was 352 and 338 times higher than that for EM for DR and HM, respectively. However, polymorphism in N-demethylation was not observed. Ratios of conjugated/free dextrorphan and 3-hydroxymorphinan excreted in the urine suggest also a lack of conjugative capacity in the PM, relative to the EM. The overall incidence of PM was 9.1% in this population.

Capillary gas chromatographic (GC) analysis of nitroglycerin and its denitration products in plasma

A convenient, specific, and sensitive capillary gas chromatographic (GC) assay for analyzing nanogram concentrations of nitroglycerin and its dinitro- and mononitrometabolites in plasma has been developed. Using a bonded-phase (DB-1) 30-m, 1-micron-thick film capillary column and a 1-m, 5-microns-thick film precolumn, separation of nitroglycerin and all four partially nitrated metabolites was achieved in less than 15 min. On-column injection, electron capture detection, and isothermal operation at 100 degrees C yielded a linear extraction curve over a 300-ng/ml range without any need to concentrate sample extracts. Using methyl t-butyl ether as extraction solvent and o-chloronitrobenzene as internal standard, recoveries from plasma spiked at levels greater than 10 ng/ml approximated 35% for the 1-monometabolite, 40% for the 2-monometabolite, and greater than 90% for all others. The method was employed in a pharmacokinetic study of nitroglycerin administered intravenously to beagle dogs. Plasma samples were collected at various time points and analyzed.

The effect of food on the absorption of controlled-release theophylline in mini-swine

The effect of differing fat contents of food on the bioavailability of theophylline following a 400-mg single dose of Theo-24 was studied in mini-swine. The pharmacokinetics of theophylline, following the intravenous administration of aminophylline equivalent to 5 mg/kg as a single dose, were also studied in the same animals. The terminal plasma half-life of theophylline following an i.v. dose was found to be approximately 24 hr. The volume of distribution, Vdext, and clearance following the i.v. dose were approximately 0.7 liter/kg and 0.023 liter/hr/kg, respectively. The terminal half-life of theophylline following the administration of theophylline capsules under fasting conditions was 21 hr. The average bioavailability under fasting conditions was approximately 80% compared to the i.v. dose. Food appeared to have decreased the rate of absorption but no significant effect on the extent of absorption.

Influence of tablet dissolution on furosemide bioavailability: a bioequivalence study

In order to evaluate the in vitro dissolution and in vivo bioavailability relationship for furosemide, a bioequivalence study was carried out. Furosemide (40 mg) was administered orally to 12 normal volunteers in a 6 x 6 crossover design using six products (five tablets and one solution) obtained from three pharmaceutical companies. Plasma and urine concentrations of furosemide were quantitated by high-performance liquid chromatography (HPLC). Plasma furosemide profiles were analyzed by non-compartmental methods. Compared to the oral solution, all of the formulations exhibited lower peak furosemide concentrations, longer mean residence times, and, in some cases, diminished bioavailability (range, 66-96%). Similar results were obtained when the reference product (a rapidly dissolving tablet) was used as the standard. All of the products failed the 75/75 rule when compared to either reference standard, apparently because of large intersubject variability. The total amount of furosemide excreted in urine could be associated with the percentage drug dissolved (in vitro) at 30 min. The pH 5.6 dissolution medium (compared to pH 4.6) appears to be an appropriate test medium for assuring batch uniformity and bioequivalence of furosemide products.

Simultaneous determination of prednisolone acetate, prednisolone, prednisone, cortisone and hydrocortisone in swine plasma using solid-phase and liquid-liquid extraction techniques

A high-performance liquid chromatographic (HPLC) method for the simultaneous determination of prednisolone acetate (PA), prednisolone (PO), prednisone (PN), cortisone and hydrocortisone in swine plasma is described. Extraction of the steroid mixture from swine plasma with dexamethasone as internal standard was accomplished by solid-phase extraction (SPE) or the more traditional liquid-liquid extraction (LLE) techniques. These compounds were analyzed by normal-phase HPLC with ultraviolet detection. Although a detectable sensitivity of 5 ng/ml is achieved by the SPE technique, the practical sensitivity is established as 10 ng/ml. Conversely, the practical sensitivity is 5 ng/ml for all compounds by the LLE technique. Calibration curves were found to be linear between 10 and 500 ng/ml by the SPE technique and between 5 and 100 ng/ml by the LLE technique. The average recovery of the steroids PA, PO and PN at 20 ng/ml is between 70 and 90%. PA is stable for up to 3 h in swine plasma at room temperature (22 degrees C) but is completely converted to PO within 24 h. PA is stable in swine plasma in an ice bath for over 24 h. The usefulness of this analytical technique is demonstrated by the intraperitoneal administration of 125 mg of PA to swine and the quantitative determination of PA, PO and PN in the plasma as a function of time.

Influence of dioctyl sodium sulfosuccinate on the absorption of tetracycline

A pilot bioavailability study was carried out to evaluate the drug interaction and influence of dioctyl sodium sulfosuccinate (DS) on the absorption/bioavailability of tetracycline. Three tetracycline products--a fast dissolving capsule, a slow dissolving capsule and a suspension, were used in the study. DS was administered 30 minutes before tetracycline administration; and on -3, -2 and -1 day in the evening before tetracycline administration. Frequent urine samples were collected up to 48 hours and analyzed by a microbiological method. Although not statistically significant in this small study, the results suggest that there is a reduction in tetracycline bioavailability due to DS. The indiscriminate use of surface active agents to increase the dissolution rate of solid oral dosage forms in the belief that the resulting increased dissolution improves product bioavailability must be questioned.

Bioavailability of hydrocortisone from commercial 20-mg tablets

The relative bioavailability of hydrocortisone was determined from four different 20-mg tablet formulations and one suspension in 15 healthy male volunteers; results were compared with in vitro dissolution rates. Plasma levels of hydrocortisone were determined by a liquid chromatography method developed in this laboratory. Dissolution of the tablet formulations, using the official USP test, varied from 7.8 to 93.8% in 30 min. Similar plasma profiles were obtained from all tablet products, and there were no differences among tablets in the cumulative percentage of drug absorbed. There were no clear trends in any pharmacokinetic parameter values among the tablet dosages, and the four products were considered bioequivalent. The suspension dosage yielded significantly higher plasma levels compared with some of the tablet formulations during the initial 30-min postdose, significantly higher cumulative absorption at 0.5 and 1.0 h compared with one tablet formulation, and significantly higher ka and Cmax, and shorter tmax values, compared with some of the tablets.

Bioavailability of hydrochlorothiazide from tablets and suspensions

The bioavailability of hydrochlorothiazide was determined following single oral 25-, 50-, 100-, and 200-mg tablet and suspension doses in 12 healthy male volunteers. Plasma and urine levels of hydrochlorothiazide were determined by HPLC. Plasma levels of hydrochlorothiazide were satisfactorily described by a triexponential function. Mean peak plasma levels, Cmax (127-135, 270-280, and 437-490 ng/mL from the 25-, 50-, and 100-mg doses, respectively) were dose proportional, as were areas under plasma profiles, AUC0----36. Mean percentage recovery of unchanged hydrochlorothiazide in 48-h urine samples accounted for 50-59, 54-55, 60-63, and 54-57% of the 25-, 50-, 100-, and 200-mg doses, respectively. There were no significant differences among these values. Correlation coefficients between 48-h urinary recovery of hydrochlorothiazide and the plasma values (Cmax and AUC0----36) for the 25-, 50-, and 100-mg doses were 0.73 and 0.84. There were no differences in the net increases in electrolyte excretion among the treatments during the 0-12-h postdose period. The systematic availability of hydrochlorothiazide, unlike that of chlorothiazide, is dose proportional in the therapeutic range.

Preliminary observations on dissolution and bioavailability of triamterene-hydrochlorothiazide combination products

The dissolution profiles of two brands of triamterene-hydrochlorothiazide (TRM-HCT) combination tablets and two brands of TRM-HCT combination capsules were studied using the USP paddle method at 100 rev min-1 in acid medium (0.1N). The tablets represent two products marketed in Germany, whereas the capsules represent the approved innovator's product and an unapproved generic product. The tablets dissolved almost 100 per cent in 15 min whereas the capsules dissolved less than 25 per cent in 60 min. A pilot bioavailability study was carried out in four normal healthy male volunteers. Urine samples were collected over a 48 h period and analysed for TRM, its major metabolite TRM-sulfate, and HCT using HPLC methods. The dissolution characteristics of TRM can be associated with the total drug excretion (absorption) of the product. On the other hand, the excretion (absorption) of HCT was independent of dissolution characteristics of the products. However, in TRM-HCT combination product, there appears to be a 50 per cent reduction in HCT excretion (absorption) when compared to the reported excretion (absorption) from a marketed single-entity product.

Thiazides XI: partitioning of chlorothiazide in red blood cells after oral administration

Uptake of chlorothiazide by red blood cells after oral drug administration was investigated. Chlorothiazide was administered to normal healthy volunteers as a solution or a tablet. Frequent blood samples were collected and analysed by a specific HPLC method. The results indicate that there is a significant uptake of chlorothiazide by red blood cells, resulting in a higher blood AUC compared to plasma AUC.

Thiazides. VIII: Dissolution survey of marketed hydrochlorothiazide tablets

The dissolution profiles of 50-mg hydrochlorothiazide tablets representing all approved manufacturers (at the time of the study) were determined in two vehicles [purified water and dilute (1:100) hydrochloric acid] by three methods (rotating basket at 150 rpm; spin filter at 300 rpm; paddle method at 50 rpm). The paddle method was preferred on the basis of overall ease of operation, reproducibility, and discrimination. The paddle data were validated in both vehicles on the same lots of tablets by a second laboratory. A standard of not less than 80% dissolution in 60 min by the paddle method in water is proposed for hydrochlorothiazide tablets.

Phenytoin II: in vitro-in vivo bioequivalence standard for 100-mg phenytoin sodium capsules

A bioequivalence study was undertaken using an oral solution, a fast-dissolving capsule and a slow-dissolving phenytoin sodium capsule. The AUC, tmax and Cmax correlated with in vitro dissolution data. The results of the present studies substantiate the presence of two types of phenytoin sodium products on the market. On the basis of these studies, in vitro specifications for fast- and slow-dissolving phenytoin sodium capsules as well as the in vivo bioequivalence requirements for these two types of products are recommended.

Phenytoin I: in vitro-in vivo correlation for 100-mg phenytoin sodium capsules

Dissolution profiles for 11 brands of phenytoin sodium capsules were carried out by the basket and paddle methods (USP) and the spin-filter method. The results from the dissolution studies have been correlated with observed differences in in vivo parameters (Cmax and tmax). The dissolution by the basket method at 50 rpm in water gave a correlation greater than 0.9. The results suggest the existence of two types of phenytoin sodium products on the market.

Thiazides III. Evidence of dose proportionality of hydrochlorothiazide 25, 50 and 100 mg tablets

A pilot bioavailability study was carried out where two subjects each were administered a dose of 25, 50 or 100 mg of commercially available hydrochlorothiazide (HCT) tablets. Plasma and urine samples were collected and analyzed by HPLC. A maximum plasma concentration of 50-285 ng/ml was reached in 1-2 hours, and plasma levels declined very rapidly with a half life of about 2-4 hours during first 12 hours period. The AUC was calculated using the trapezodial rule. A linear correlation was seen between the dose administered and amount of drug excreted.

Evaluation of basket and paddle dissolution methods using different performance standards

Dissolution studies using both basket and paddle methods were carried out to evaluate two prednisone standards. Results of the experiments showed that the USP prednisone calibrator is sensitive to perturbations by the basket method but not to perturbations by the paddle method. However, the National Center for Drug Analysis (NCDA) prednisone performance standard is sensitive to perturbations by the paddle method but not to perturbations by the basket method. These results suggest that no single standard can predict the suitability of the dissolution equipment by the basket and paddle methods.

Thiazides IV: Comparison of dissolution with bioavailability of chlorothiazide tablets

Based on the initial dissolution rate profiles in water, a slow-dissolving, an intermediate-dissolving, and a fast-dissolving chlorothiazide 250-mg tablet were selected for the bioavailability and bioequivalence study. In addition, two marketed 500-mg chlorothiazide tablets were studied. The three 250-mg tablets were bioequivalent, as were the two 500-mg tablets. Therefore, the dissolution test conditions were modified to associate in vitro dissolution with in vivo performance of the product. Based on these results, it was concluded that a dissolution of 75% in 60 min by paddle method at 75 rpm in pH 7.4 phosphate buffer can be used as a quality assurance test for 250- and 500-mg chlorothiazide tablets.

Oral hydrocortisone pharmacokinetics: a comparison of fluorescence and ultraviolet high-pressure liquid chromatographic assays for hydrocortisone in plasma

Three fasted, male subjects received single 10-, 30-, and 50-mg oral doses of hydrocortisone tablets on separate occasions. Endogenous hydrocortisone was suppressed by giving 2 mg of dexamethasone 9 hr prior to dosing. Plasma samples obtained serially for 8 hr after hydrocortisone dosing were assayed by reversed-phase high-pressure liquid chromatography (HPLC) with UV detection and by normal-phase HPLC with fluorescence detection of the dansylhydrazine derivative of hydrocortisone. The two assay methods yielded equivalent plasma hydrocortisone concentrations. Metabolite interference was absent in both assay methods. Drug concentrations in plasma from all three doses of hydrocortisone were described by one-compartment open-model kinetics, with first-order absorption and elimination, and an absorption lag time. Mean Cmax values of 199, 393, and 419 ng/ml were obtained at 1.0, 1.0, and 1.7 hr following the 10-, 30-, and 50-mg doses, respectively. Hydrocortisone was cleared from plasma with an elimination half-life of approximately 1.5 hr. Within the dosage range studied, plasma levels of hydrocortisone were related, but not directly proportional, to dose size. This apparent lack of proportionality may be due to reduced drug availability or altered distribution with increasing dose.

Improved method for the analysis of furosemide in plasma by high-performance liquid chromatography

Modifications of existing rapid high-performance liquid chromatographic procedures for the determination of furosemide in plasma were made in order to achieve greater sensitivity. To a small volume of plasma was added in internal standard structurally related to furosemide. Then, following previously described procedures, acetonitrile was added to precipitate the proteins and the clear supernatant was separated. However prior to injection of the supernatant the pH and composition of the sample were adjusted. This modification of the sample enabled an injection volume of up to 300 microliters of the supernatant to be injected onto the chromatographic column. The effluent was monitored spectrofluorimetrically. A standard linear calibration curve with a mean precision of +/- 4.4% was obtained for plasma samples containing 20--900 ng/ml of furosemide. Two structurally related compounds were used as internal standards in the furosemide assay.

Dissolution profiles and specifications for dihydroergotoxine sublingual tablets using a new in vitro method

A dissolution method (paddle method) for determining the dissolution rate profile for 0.5- and 1.0-mg dihydroergotoxine methanesulfonate sublingual tablets was developed. A fluorometric method was used for measuring drug concentration in the dissolution medium, distilled water. It was essential to filter the dissolution sample to avoid interference from undissolved excipients. When different kinds of filters were used with the dissolution samples and standards, different degrees of apparent drug binding to the filter occurred. The dissolution rate profiles for several different products were compared to the innovator's product. The in vitro method and data obtained were used to propose dissolution specifications for these sublingual products.

Simple high-performance liquid chromatographic assay for norethindrone--mestranol in combination tablets

A simple, sensitive, and specific high-performance liquid chromatographic procedure was developed to assay norethindrone--mestranol combination tablets. The method involves a chloroform extraction of a single pulverized tablet. After centrifugation, and aliquot of the supernate was injected into a modular high-performance liquid chromatograph. The effluent from the silica column was monitored serially with a fixed-wavelength UV detector (254 nm) for norethindrone quantitation and a fluorescence detector (230 nm for excitation and 280 nm cutoff filter for emission) for mestranol quantitation. Progesterone was used as an internal standard. The method was employed successfully in content uniformity studies of several brands of commercially available tablets.