The North Pacific biological pump: Rates, efficiency and influence on ocean carbon uptake

Thesis (Ph.D.)--University of Washington, 2016-05

Drug utilization evaluation of parenteral proton pump inhibitors

Current evidence supports parenteral infusion of proton pump inhibitors (PPI) after endoscopic treatment of bleeding peptic ulcers and such treatment seems reasonable where there is active bleeding or visible vessel on endoscopy. Parenteral boluses of PPI can be used in patients nil by mouth who cannot tolerate oral therapy. We sought to examine the appropriateness of parenteral PPI use. Drug utilisation evaluation was performed on 94 patients admitted to a 500 bed metropolitan hospital. 39 patients received continuous parenteral infusion of omeprazole (8 mg/ h) over a mean of 60 ± 29 h. 55 patients had parenteral boluses (40 mg bd) of omeprazole over a mean of 5 ± 4 days. Indications for PPI infusion (n = 39) were: major haemorrhage requiring transfusion (23), minor haemorrhage (8), dyspepsia (4) and others (4). 31 of the 39 patients on PPI infusion had upper gastrointestinal (GI) endoscopy. PPI infusion was commenced prior to endoscopy in 26 (84%) patients. 13 patients (33%) had active bleeding or visible non bleeding vessels at endoscopy. Only 11 patients (28%) had endoscopically treated peptic ulcers. Indications for parenteral PPI boluses (n = 55) included patients nil by mouth unable to take maintenance PPI orally (21), minor haemorrhage (8), peptic ulcer prophylaxis in seriously unwell (6), major haemorrhage (4), dyspepsia (2), postoprative period following peptic ulcer surgery (2) and others (12). Endoscopy was performed in 10 patients (18%) with only 1 endoscopically treated peptic ulcer. Our data suggest significant inappropriate use of parenteral PPI, which may be used for minor GI bleeding and dyspepsia and are typically commenced prior to endoscopy. These findings can explain the costly hospital expenditure on PPI.

A new rapidly absorbed paracetamol tablet containing sodium bicarbonate. II. Dissolution studies and in vitro/in vivo correlation

The objective of this study was to compare the in vitro dissolution profile of a new rapidly absorbed paracetamol tablet containing sodium bicarbonate (PS) with that of a conventional paracetamol tablet (P), and to relate these by deconvolution and mapping to in vivo release. The dissolution methods used include the standard procedure described in the USP monograph for paracetamol tablets, employing buffer at pH5.8 or 0.05 M HCl at stirrer speeds between 10 and 50 rpm. The mapping process was developed and implemented in Microsoft Excel® worksheets that iteratively calculated the optimal values of scale and shape factors which linked in vivo time to in vitro time. The in vitro-in vivo correlation (IVIVC) was carried out simultaneously for both formulations to produce common mapping factors. The USP method, using buffer at pH5.8, demonstrated no difference between the two products. However, using an acidic medium the rate of dissolution of P but not of PS decreased with decreasing stirrer speed. A significant correlation (r=0.773; p<.00001) was established between in vivo release and in vitro dissolution using the profiles obtained with 0.05 M HCl and a stirrer speed of 30 rpm. The scale factor for optimal simultaneous IVIVC in the fasting state was 2.54 and the shape factor was 0.16; corresponding values for mapping in the fed state were 3.37 and 0.13 (implying a larger in vitro-in vivo time difference but reduced shape difference in the fed state). The current IVIVC explains, in part, the observed in vivo variability of the two products. The approach to mapping may also be extended to different batches of these products, to predict the impact of any changes of in vitro dissolution on in vivo release and plasma drug concentration-time profiles.

Signal power excursion and pump efficiency in quasi-lossless ultra-long Raman laser links

Performance optimisation of ultra-long Raman laser links is studied theoretically and experimentally. We observe that it is possible to reduce signal power excursion by adjusting FBG reflectivity without compromising pump efficiency.