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Three leading and competitive commercial products of paracetamol tablets coded as brands A, B and C (A, being the innovator product) in the country were evaluated for their in vitro properties and in vivo comparative bioavailability. The studies included chemical equivalence, hardness, disintegration time, dissolution rate and systemic availability among eight healthy volunteers. The disintegration times were 2.1 min for brand A, 5.7 min for brand B and 36.2 min for brand C. The dissolution rate (T70) were 33.0 min, 74.5 min and 56.5 min for brands A, B and C, respectively. While brand A passed all the in vitro tests as specified in the official monograph, brand B failed only the dissolution rate test and brand C failed both the disintegration and dissolution tests. These significant differences observed among the products after in vitro tests were not reflected in the in vivo availability. While the absorption rate (indicated by tmax) of brand C was significantly faster (i.e. shorter) than those of Brands A and B, the extent of absorption (indicated by AUC) was comparable among the three brands. The relative bioavailabilities (with respect to brand A) were 92 and 91% for brands B and C, respectively indicating that the products were bioequivalent. Comparison of the in vitro and in vivo data suggest that the systemic absorption of paracetamol may not be dissolution--rate limited and that using in vitro dissolution rate studies alone to establish bioequivalency of paracetamol tablets should be done with caution. 相似文献
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RN Shain JM Piper ER Newton ST Perdue R Ramos JD Champion FA Guerra 《Canadian Metallurgical Quarterly》1999,340(2):93-100
Using annual bite-wing radiographs, the incidence and progression of approximal caries (4d-7m) were assessed longitudinally in teenagers and adolescents whose treatment had been based on remineralizing rather than restorative strategies. A closed cohort of 536 children initially was followed from 11 to 22 years of age. The scoring system was: 0 = no visible radiolucency; 1-2 = radiolucency in the enamel up to the enamel-dentin border; 3 = radiolucency with a broken enamel-dentin border but with no obvious progression in the dentin; 4 = radiolucency with obvious spread in the outer half of the dentin, and 5 = radiolucency in the inner half of the dentin. Caries rates were estimated as the number of new lesions/100 tooth surface-years, and the Kaplan-Meier estimate was used to calculate the cumulative survival time of each approximal surface. Three events were used: the transitions from states 0 to 2, 2 to 4 and 3 to 4. The results showed a considerable variation between the surfaces in both caries rates and survival time. For all surfaces combined, the median caries rate from state 0 to 2 was 3.9 new lesions/100 tooth surface-years; from state 2 to 4, the rate was 5.4, and from state 3 to 4 it was 20.3. Of the sound surfaces (state 0), 75% survived 6.3 years without reaching state 2. Given state 2, 75% survived 4.8 years without reaching the outer half of the dentin (state 4), while given a lesion at the enamel-dentin border (state 3), 75% survived 1.3 years without doing the same. The median survival time of lesions from state 3 to 4 was 3.1 years. The group with DMFSappr>1 at the age of 11-12 years had a risk of new approximal enamel lesions (state 0-2) that was 2.5 times greater than that of the group with DMFSappr = 0-1. 相似文献
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JM Simas JT Huber CB Theurer KH Chen FA Santos Z Wu 《Canadian Metallurgical Quarterly》1997,80(11):2907-2912
Forty-eight lactating Holstein cows averaging 81 d in milk were allotted to eight blocks based on milk yield during the 14-d pretreatment period and randomly assigned to six treatment groups in a 2 x 3 factorial arrangement of treatments for 64 d. Factors were type of sorghum grain processing [dry-rolled vs. steam-flaked; fed at 34% of dry matter (DM) in a total mixed ration (TMR) based on alfalfa] and type of supplemental fat (2.5% of DM as cottonseed oil, tallow, or prilled fatty acids). Compared with dry-rolled sorghum, steam-flaked sorghum did not affect milk yield, fat percentage, or fat yield but did increase milk protein percentage, body weight gains, and estimated net energy for lactation (22%). Fat source did not affect lactational response, but, compared with tallow, prilled fatty acids tended to decrease DM intake. Steam-flaked sorghum, compared with dry-rolled sorghum, increased digestibilities of DM, organic matter, crude protein, and starch, regardless of fat source. The TMR containing prilled fat had lower digestibilities of DM and organic matter than did TMR containing cottonseed oil or tallow; and TMR containing prilled fat had lower digestibilities of crude protein and total fatty acids than did TMR containing tallow. This study showed that steam-flaking of sorghum grain increased milk protein content, body weight gains, and estimated net energy for lactation, regardless of dietary fat source. 相似文献
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SA Gould EE Moore FA Moore JB Haenel JM Burch H Sehgal L Sehgal R DeWoskin GS Moss 《Canadian Metallurgical Quarterly》1997,43(2):325-31; discussion 331-2
We have previously documented the safety of 1 unit (50 gram) of human polymerized hemoglobin (Poly SFH-P) in healthy volunteers. This report describes the first patient trial to assess the therapeutic benefit of Poly SFH-P in acute blood loss. Thirty-nine patients received 1 (n = 14), 2 (n = 2), 3 (n = 15), or 6 (n = 8) units of Poly SFH-P instead of red cells as part of their blood replacement after trauma and urgent surgery. There were no safety issues related to the infusion of Poly SFH-P. The plasma hemoglobin concentration ([Hb]) after the infusion of 6 units (300 gram) of Poly SFH-P was 4.8 +/- 0.8 g/dL (mean +/- SD). Although the red cell [Hb] fell to 2.9 +/- 1.2 g/dL, the total [Hb] was maintained at 7.5 +/- 1.2 g/dL. Poly SFH-P maintained total [Hb], despite the marked fall in red cell [Hb] due to blood loss. The utilization of O2 (extraction ratio) was 27 +/- 16% from the red cells and 37 +/- 13% from the Poly SFH-P. Twenty-three patients (59%) avoided allogeneic transfusions during the first 24 hours after blood loss. Poly SFH-P effectively loads and unloads O2 and maintains total hemoglobin in lieu of red cells after acute blood loss, thereby reducing allogeneic transfusions. Poly SFH-P seems to be a clinically useful blood substitute. 相似文献
90.
Numerical results of a model with variable infectivity for the dynamics of HIV/AIDS (human immunodeficiency virus/acquired immune deficiency syndrome) have been compared with the data of AIDS cases among intravenous drug users in Italy, especially in the Latium region. We examined several hypotheses about the dynamics of the epidemics; for each we obtained, mainly through a least-square approach but also minimizing a different quantity, a best-fit estimate of the parameters. In the simplest model, the population is assumed to be homogeneous, and we estimate contact rate and year of start of the epidemics, obtaining a good fit up to 1989, less so after. A substantial increase in fit is obtained in assuming either a decrease of the contact rate over time or a heterogeneous population with a smaller active group. We have also compared models with different infectivity curves during the incubation period: the assumption of constant infectivity is untenable, whereas the often suggested hypothesis of a peak in infectivity shortly after infection seems to be in agreement with data. 相似文献