Relaxation matrix for symmetric tops with inversion symmetry: Line coupling and line mixing effects on NH3 lines in the 𝝂4 band.

Line shape parameters including the half-widths and the off-diagonal elements of the relaxation matrix have been calculated for self-broadened NH3 lines in the perpendicular ν4 band. As in the pure rotational and the parallel ν1 bands, the small inversion splitting in this band causes a complete failure of the isolated line approximation. As a result, one has to use formalisms not relying on this approximation. However, due to differences between parallel and perpendicular bands of NH3, the applicability of the formalism used in our previous studies of the ν1 band and other parallel bands must be carefully verified. We have found that, as long as potential models only contain components with K1 = K2 = 0, whose matrix elements require the selection rule Δk = 0, the formalism is applicable for the ν4 band with some minor adjustments. Based on both theoretical considerations and results from numerical calculations, the non-diagonality of the relaxation matrices in all the PP, RP, PQ, RQ, PR, and RR branches is discussed. Theoretically calculated self-broadened half-widths are compared with measurements and the values listed in HITRAN 2012. With respect to line coupling effects, we have compared our calculated intra-doublet off-diagonal elements of the relaxation matrix with reliable measurements carried out in the PP branch where the spectral environment is favorable. The agreement is rather good since our results do well reproduce the observed k and j dependences of these elements, thus validating our formalism.

VIBRATIONAL DEPENDENCE OF LINE COUPLING AND LINE MIXING IN SELF-BROADENED PARALLEL BANDS OF NH3.

Line coupling and line mixing effects have been calculated for several self-broadened NH3 lines in parallel bands involving an excited v 2 mode. It is well known that once the v 2 mode is excited, the inversion splitting quickly increases as this quantum number increases. In the present study, we have shown that the v 2 dependence of the inversion splitting plays a dominant role in the calculated line-shape parameters. For the v 2 band with a 36 cm-1 splitting, the intra-doublet couplings practically disappear and for the 2v 2 and 2v 2 - v 2 bands with much higher splitting values, they are completely absent. With respect to the inter-doublet coupling, it becomes the most efficient coupling mechanism for the v 2 band, but it is also completely absent for bands with higher v 2 quantum numbers. Because line mixing is caused by line coupling, the above conclusions on line coupling are also applicable for line mixing. Concerning the check of our calculated line mixing effects, while the present formalism has well explained the line mixing signatures observed in the v 1 band, there are large discrepancies between the measured Rosenkranz mixing parameters and our calculated results for the v 2 and 2v 2 bands. In order to clarify these discrepancies, we propose to make some new measurements. In addition, we have calculated self-broadened half-widths in the v 2 and 2v 2 bands and made comparisons with several measurements and with the values listed in HITRAN 2012. In general, the agreements with measurements are very good. In contrast, the agreement with HITRAN 2012 is poor, indicating that the empirical formula used to predict the HITRAN 2012 data has to be updated.

Line mixing in parallel and perpendicular bands of CO2: A further test of the refined Robert-Bonamy formalism.

Starting from the refined Robert-Bonamy formalism [Q. Ma, C. Boulet, and R. H. Tipping, J. Chem. Phys. 139, 034305 (2013)], we propose here an extension of line mixing studies to infrared absorptions of linear polyatomic molecules having stretching and bending modes. The present formalism does not neglect the internal degrees of freedom of the perturbing molecules, contrary to the energy corrected sudden (ECS) modelling, and enables one to calculate the whole relaxation matrix starting from the potential energy surface. Meanwhile, similar to the ECS modelling, the present formalism properly accounts for roles played by all the internal angular momenta in the coupling process, including the vibrational angular momentum. The formalism has been applied to the important case of CO2 broadened by N2. Applications to two kinds of vibrational bands (Σ â†’ Σ and Σ â†’ Π) have shown that the present results are in good agreement with both experimental data and results derived from the ECS model.

Effects on calculated half-widths and shifts from the line coupling for asymmetric-top molecules.

The refinement of the Robert-Bonamy formalism by considering the line coupling for linear molecules developed in our previous studies [Q. Ma, C. Boulet, and R. H. Tipping, J. Chem. Phys. 139, 034305 (2013); 140, 104304 (2014)] have been extended to asymmetric-top molecules. For H2O immersed in N2 bath, the line coupling selection rules applicable for the pure rotational band to determine whether two specified lines are coupled or not are established. Meanwhile, because the coupling strengths are determined by relative importance of off-diagonal matrix elements versus diagonal elements of the operator -iS1 - S2, quantitative tools are developed with which one is able to remove weakly coupled lines from consideration. By applying these tools, we have found that within reasonable tolerances, most of the H2O lines in the pure rotational band are not coupled. This reflects the fact that differences of energy levels of the H2O states are pretty large. But, there are several dozen strongly coupled lines and they can be categorized into different groups such that the line couplings occur only within the same groups. In practice, to identify those strongly coupled lines and to confine them into sub-linespaces are crucial steps in considering the line coupling. We have calculated half-widths and shifts for some groups, including the line coupling. Based on these calculations, one can conclude that for most of the H2O lines, it is unnecessary to consider the line coupling. However, for several dozens of lines, effects on the calculated half-widths from the line coupling are small, but remain noticeable and reductions of calculated half-widths due to including the line coupling could reach to 5%. Meanwhile, effects on the calculated shifts are very significant and variations of calculated shifts could be as large as 25%.

Two dimensional symmetric correlation functions of the S operator and two dimensional Fourier transforms: considering the line coupling for P and R lines of linear molecules.

The refinement of the Robert-Bonamy (RB) formalism by considering the line coupling for isotropic Raman Q lines of linear molecules developed in our previous study [Q. Ma, C. Boulet, and R. H. Tipping, J. Chem. Phys. 139, 034305 (2013)] has been extended to infrared P and R lines. In these calculations, the main task is to derive diagonal and off-diagonal matrix elements of the Liouville operator iS1 - S2 introduced in the formalism. When one considers the line coupling for isotropic Raman Q lines where their initial and final rotational quantum numbers are identical, the derivations of off-diagonal elements do not require extra correlation functions of the S operator and their Fourier transforms except for those used in deriving diagonal elements. In contrast, the derivations for infrared P and R lines become more difficult because they require a lot of new correlation functions and their Fourier transforms. By introducing two dimensional correlation functions labeled by two tensor ranks and making variable changes to become even functions, the derivations only require the latters' two dimensional Fourier transforms evaluated at two modulation frequencies characterizing the averaged energy gap and the frequency detuning between the two coupled transitions. With the coordinate representation, it is easy to accurately derive these two dimensional correlation functions. Meanwhile, by using the sampling theory one is able to effectively evaluate their two dimensional Fourier transforms. Thus, the obstacles in considering the line coupling for P and R lines have been overcome. Numerical calculations have been carried out for the half-widths of both the isotropic Raman Q lines and the infrared P and R lines of C2H2 broadened by N2. In comparison with values derived from the RB formalism, new calculated values are significantly reduced and become closer to measurements.

Refinement of the Robert-Bonamy formalism: considering effects from the line coupling.

Since it was developed in 1979, the Robert-Bonamy (RB) formalism has been widely used in calculating pressure broadened half-widths and induced shifts for many molecular systems. However, this formalism contains several approximations whose applicability has not been thoroughly justified. One of them is that lines of interest are well isolated. When these authors developed the formalism, they have relied on this assumption twice. First, in calculating the spectral density F(ω), they have only considered the diagonal matrix elements of the relaxation operator. Due to this simplification, effects from the line mixing are ignored. Second, when they applied the linked cluster theorem to remove the cutoff, they have assumed the matrix elements of the operator exp(-iS1 - S2) can be replaced by the exponential of the matrix elements of -iS1 - S2. With this replacement, effects from the line coupling are also ignored. Although both these two simplifications relied on the same approximation, their validity criteria are completely different and the latter is more stringent than the former. As a result, in many cases where the line mixing becomes negligible, significant effects from the line coupling have been completely missed. In the present study, we have developed a new method to evaluate the matrix elements of exp(-iS1 - S2) and have refined the RB formalism such that line coupling can be taken into account. Our numerical calculations of the half-widths for Raman Q lines of the N2-N2 pair have demonstrated that effects from the line coupling are important. In comparison with values derived from the RB formalism, new calculated values for these lines are significantly reduced. A recent study has shown that in comparison with the measurements and the most accurate close coupling calculations, the RB formalism overestimates the half-widths by a large amount. As a result, the refinement of the RB formalism goes in the right direction and these new calculated half-widths become closer to the "true" values.

Temperature dependences of mechanisms responsible for the water-vapor continuum absorption. II. Dimers and collision-induced absorption.

We investigated the magnitude and temperature dependence (T dependence) of the dimer absorption in the region of 0-600 cm(-1) and the collision-induced absorption (CIA) in the region of 0-1150 cm(-1). Together with our previous study of the self water-vapor continuum contributions resulting from far-wing line shapes of the allowed H(2)O lines in the infrared window between 800 and 1150 cm(-1), we find that the three mechanisms have completely different T dependence behaviors. The dimer absorption has the strongest negative T dependence and the continuum absorption from far wings of the allowed lines has a moderately strong negative one. Meanwhile, the CIA exhibits a mild T dependence. In addition, their T dependence patterns are quite different. The T dependence of the far-wing theory varies significantly as the frequency of interest omega varies. For CIA, in general, its T dependence is mildly negative, but becomes slightly positive in the window region between the H(2)O bands. In contrast, the T dependence of the dimer absorption varies slightly as omega varies. In the microwave and submillimeter region, its T dependence becomes uniform. Concerning the relative importance for each of these three mechanisms, we find that in the infrared widow, the far-wing contributions are the dominant source of the self-continuum. Within the band, its contributions are definitely responsible for the measured continuum data. But, it is impossible to draw quantitatively conclusions on its relative importance unless one is able to improve the accuracy of the local line calculations significantly. On the other hand, within the pure rotational band, the dimer absorptions are a minor contributor to the self-continuum measurements, and its role becomes more important in the microwave and submillimeter regions. Finally, based on our study we conclude that contributions to the self-continuum from CIA in the frequency region of 0-1150 cm(-1) are negligible.

Critical Care Air Support Teams and deployed intensive care.

The evacuation of injured patients by air has been going on in one form or another for nearly 100 years. This paper presents some of the history behind Aeromedical Evacuation (AE), the current situation and looks to the future of this vital component in the chain of care from point of wounding to rehabilitation.

Temperature dependences of mechanisms responsible for the water-vapor continuum absorption. I. Far wings of allowed lines.

It is well known that the water-vapor continuum plays an important role in the radiative balance in the Earth's atmosphere. This was first discovered by Elsasser almost 70 years ago, and since that time there has been a large body of work, both experimental and theoretical, on this topic. It has been experimentally shown that for ambient atmospheric conditions, the continuum absorption scales quadratically with the H(2)O number density and has a strong, negative temperature dependence (T dependence). Over the years, there have been three different theoretical mechanisms postulated: Far wings of allowed transitions, water dimers, and collision-induced absorption. Despite the improvements in experimental data, at present there is no consensus on which mechanism is primarily responsible for the absorption. The first mechanism proposed was the accumulation of the far-wing absorption of the strong allowed transitions. Later, absorption by water dimers was proposed and this mechanism provides a qualitative explanation for the strong, negative T dependence. Recently, some atmospheric modelers have proposed that collision-induced absorption is one of the major contributors. However, based on improvements in the theoretical calculation of accurate far-wing line shapes, ab initio dimer calculations, and theoretical collision-induced absorptions, it is now generally accepted that the dominant mechanism for the absorption in the infrared (IR) windows is that due to the far wings. Whether this is true for other spectral regions is not presently established. Although all these three mechanisms have a negative T dependence, their T dependences will be characterized by individual features. To analyze the characteristics of the latter will enable one to assess their roles with more certainty. In this paper, we present a detailed study of the T dependence of the far-wing absorption mechanism. We will then compare our theoretical calculations with the most recent and accurate experimental data in the IR windows. The results of our calculations are found to agree very well with measurements in the 800-1200 cm(-1) region. We conclude from this work that the T dependence in the IR window region predicted by the far-wing theory is negative and moderately strong. Its pattern is not simple and it could vary significantly as the frequency of interest varies.

The Emerging Risk Factors Collaboration: analysis of individual data on lipid, inflammatory and other markers in over 1.1 million participants in 104 prospective studies of cardiovascular diseases.

Many long-term prospective studies have reported on associations of cardiovascular diseases with circulating lipid markers and/or inflammatory markers. Studies have not, however, generally been designed to provide reliable estimates under different circumstances and to correct for within-person variability. The Emerging Risk Factors Collaboration has established a central database on over 1.1 million participants from 104 prospective population-based studies, in which subsets have information on lipid and inflammatory markers, other characteristics, as well as major cardiovascular morbidity and cause-specific mortality. Information on repeat measurements on relevant characteristics has been collected in approximately 340,000 participants to enable estimation of and correction for within-person variability. Re-analysis of individual data will yield up to approximately 69,000 incident fatal or nonfatal first ever major cardiovascular outcomes recorded during about 11.7 million person years at risk. The primary analyses will involve age-specific regression models in people without known baseline cardiovascular disease in relation to fatal or nonfatal first ever coronary heart disease outcomes. This initiative will characterize more precisely and in greater detail than has previously been possible the shape and strength of the age- and sex-specific associations of several lipid and inflammatory markers with incident coronary heart disease outcomes (and, secondarily, with other incident cardiovascular outcomes) under a wide range of circumstances. It will, therefore, help to determine to what extent such associations are independent from possible confounding factors and to what extent such markers (separately and in combination) provide incremental predictive value.

Irreducible correlation functions of the S matrix in the coordinate representation: application in calculating Lorentzian half-widths and shifts.

By introducing the coordinate representation, the derivation of the perturbation expansion of the Liouville S matrix is formulated in terms of classically behaved autocorrelation functions. Because these functions are characterized by a pair of irreducible tensors, their number is limited to a few. They represent how the overlaps of the potential components change with a time displacement, and under normal conditions, their magnitudes decrease by several orders of magnitude when the displacement reaches several picoseconds. The correlation functions contain all dynamical information of the collision processes necessary in calculating half-widths and shifts and can be easily derived with high accuracy. Their well-behaved profiles, especially the rapid decrease of the magnitude, enables one to transform easily the dynamical information contained in them from the time domain to the frequency domain. More specifically, because these correlation functions are well time limited, their continuous Fourier transforms should be band limited. Then, the latter can be accurately replaced by discrete Fourier transforms and calculated with a standard fast Fourier transform method. Besides, one can easily calculate their Cauchy principal integrations and derive all functions necessary in calculating half-widths and shifts. A great advantage resulting from introducing the coordinate representation and choosing the correlation functions as the starting point is that one is able to calculate the half-widths and shifts with high accuracy, no matter how complicated the potential models are and no matter what kind of trajectories are chosen. In any case, the convergence of the calculated results is always guaranteed. As a result, with this new method, one can remove some uncertainties incorporated in the current width and shift studies. As a test, we present calculated Raman Q linewidths for the N2-N2 pair based on several trajectories, including the more accurate "exact" ones. Finally, by using this new method as a benchmark, we have carried out convergence checks for calculated values based on usual methods and have found that some results in the literature are not converged.

Efficacy and tolerability of timolol maleate ophthalmic gel-forming solution versus timolol ophthalmic solution in adults with open-angle glaucoma or ocular hypertension: a six-month, double-masked, multicenter study.

BACKGROUND: Timolol has been formulated in a highly purified gellan gum to improve its duration of action. The efficacy of this formulation in short-term studies using once-daily dosing has been reported. OBJECTIVE: The purpose of this study was to evaluate the efficacy and tolerability of 0.5% timolol maleate ophthalmic gel-forming solution (timolol GS) given once daily versus 0.5% timolol solution given twice daily in a long-term trial. METHODS: This was a multicenter, double-masked, 6-month trial. After a washout of ocular hypotensive medication, 286 patients with open-angle glaucoma or ocular hypertension were randomly assigned in a 2:1 ratio to receive 0.5% timolol GS in both eyes once daily or 0.5% timolol solution in both eyes twice daily. All patients received a morning (9 AM) and evening (9 PM) dose. For patients in the timolol GS group, the evening dose consisted of a vehicle only, whereas for patients in the timolol solution group, both doses consisted of active drug. Intraocular pressure (IOP) was measured at trough (before morning instillation) and peak (2 hours after instillation) at follow-up examinations at weeks 2, 4, 8, 12, and 24. Adverse events were monitored using patient reports. RESULTS: Of the 286 patients randomized, 191 received timolol GS and 95 received timolol solution. Ninety-three percent of patients (265/286) completed the study. At the end of the treatment interval (week 24), the mean decrease in IOP at trough ranged from 5.6 to 5.9 mm Hg in the timolol GS group and from 6.3 to 6.6 mm Hg in the timolol solution group. Similar efficacy was observed at 11 AM (peak). At week 24, the difference in mean IOP between treatments was -0.61 mm Hg (95% CI -1.44 to 0.22) at trough and -0.79 mm Hg (95% CI -1.77 to 0.20) at peak, indicating no significant difference between the 2 timolol formulations. The number of reports of blurred vision and tearing was significantly higher in the timolol GS group than in the timolol solution group (P = 0.04), whereas burning/stinging was reported more frequently in the timolol solution group than in the timolol GS group (P = 0.04). At week 12, the decrease in mean heart rate at trough (hour 0) was significantly less for patients in the timolol GS group than for those in the timolol solution group (-1.1 vs -4.2 bpm; P = 0.024). At week 24 (hour 0), the decrease in mean heart rate was less for patients treated with timolol GS by 2.5 bpm (P = 0.051). The heart rate data at peak (hour 2) was similar to that observed at trough at week 12 (-2.7 vs -5.7 bpm; P = 0.006) and week 24 (-3.1 vs -4.7 bpm; P = 0.063). The mean change in blood pressure was not significantly different between treatments. There were no clinically significant differences between the groups in visual acuity, biomicroscopy and ophthalmoscopy results, or visual fields. CONCLUSIONS: Timolol 0.5% GS administered once daily was shown to be as effective in lowering IOP as the equivalent concentration of timolol 0.5% solution administered twice daily in patients with ocular hypertension or open-angle glaucoma.

Theoretical Study of Collision-Induced Double Transitions in CO(2)-X(2) (X(2) = H(2), N(2), and O(2)) Pairs.

The double vibrational collision-induced absorptions CO(2) (nu(3) = 1) + X(2) (nu(1) = 1) <-- CO(2) (nu(3) = 0) + X(2) (nu(1) = 0), for X(2) = H(2), N(2), and O(2) are studied on the basis of quantum lineshapes computed using isotropic potentials and dipole-induced dipole functions. The linestrengths and energies of the vibration-rotation transitions are treated explicitly for X(2) and utilizing the HITRAN database for CO(2). From the frequency-dependent absorption profiles, the integrated absorption intensities are determined to be 7.2 +/- 1.2, 1.2 +/- 0.1, and 1.1 +/- 0.2 (10(-4) cm(-2) amagat(-2)) for the H(2), N(2), and O(2) collision partners, respectively. The integrated intensities for H(2) and N(2) agree well with previously measured and calculated results, while the value for O(2), which represents the first theoretical determination for this absorption, is approximately four times greater than the only experimental measurement (0.29 x 10(-4) cm(-2) amagat(-2)). Copyright 2001 Academic Press.

Theoretical far-wing line shape and absorption for high-temperature CO2.

Theoretical results for the far-wing line shapes and corresponding absorption coefficients in the high-frequency wing of the nu(3) fundamental band of self-broadened CO(2) are presented for a number of temperatures between 218 and 751 K. These first-principles calculations are made assuming binary collisions within the framework of a quasi-static theory with a more accurate interaction potential than in previous calculations. The theoretical results are compared with existing laboratory data and are in good agreement for all the temperatures considered.

A comparison of dorzolamide and timolol in patients with pseudoexfoliation and glaucoma or ocular hypertension.

PURPOSE: The purpose of the study is to compare the efficacy and safety profile of 2.0% dorzolamide (three times daily) and 0.5% timolol (twice daily) for up to 6 months in patients with glaucoma or ocular hypertension associated with pseudoexfoliation. The additive effects of dorzolamide and timolol in patients requiring add-on therapy also was evaluated. METHODS: This was a double-masked, randomized, parallel comparison study at 15 Scandinavian sites. One hundred eighty-four patients with pseudoexfoliation and either glaucoma or ocular hypertension who were 21 to 85 years of age were studied. The treatment groups were 2.0% dorzolamide three times daily and 0.5% timolol maleate twice daily. RESULTS: At 6 months, the mean percent reduction in intraocular pressure of 2% dorzolamide and 0.5% timolol was 24% and 29%, respectively, at morning peak and 21% and 23%, respectively, at afternoon trough. The additional intraocular pressure-lowering effect of adding 2.0% dorzolamide twice daily to patients receiving timolol was 14% and 15%, at peak and trough, respectively. There were no differences between treatment groups in the incidence of clinical adverse experiences, and dorzolamide was not associated with the systemic adverse effects typically ascribed to the use of oral carbonic anhydrase inhibitors. CONCLUSION: Two percent dorzolamide (three times daily) was effective and well tolerated in patients with glaucoma or ocular hypertension associated with pseudoexfoliation over the course of 6 months; 0.5% timolol (twice daily) had a greater level of intraocular pressure-lowering activity than did dorzolamide, although the difference between the two treatments became less pronounced during the study period. Finally, 2.0% dorzolamide (twice daily) produced additional lowering of intraocular pressure when given with 0.5% timolol (twice daily).

The use of dorzolamide and pilocarpine as adjunctive therapy to timolol in patients with elevated intraocular pressure. The Dorzolamide Additivity Study Group.

PURPOSE: To report the results of two studies on the use of dorzolamide as adjunctive therapy to timolol in patients with elevated intraocular pressure (IOP). In the larger study, the additive effect of dorzolamide administered twice daily also was compared with 2% pilocarpine. METHODS: Both studies were parallel, randomized, double-masked, placebo-controlled comparisons. In the pilot study, 32 patients received 0.5% timolol twice daily plus either 2% dorzolamide twice daily or placebo twice daily for 8 days. In the Pilocarpine Comparison Study, 261 patients received 0.5% timolol twice daily plus 0.7% dorzolamide twice daily, 2% dorzolamide twice daily, 2% pilocarpine four times daily, or placebo (twice daily or 4 times daily) for 2 weeks. Patients then entered a 6-month extension period and received 0.5% timolol twice daily plus either 0.7% dorzolamide twice daily, 2% dorzolamide twice daily, or 2% pilocarpine four times daily. RESULTS: In the pilot study, after 8 days, additional mean percent reductions in IOP for 2% dorzolamide and placebo were 17% and 3% at morning trough and 19% and 2% at peak, respectively. In the Pilocarpine Comparison Study, after 6 months, additional mean percent reductions in IOP (morning trough) were 9%, 13%, and 10% for 0.7% dorzolamide, 2% dorzolamide, and 2% pilocarpine, respectively. Patients receiving 2% pilocarpine had the highest rate of discontinuation due to a clinical adverse experience, and the use of dorzolamide was not associated with systemic side effects commonly observed with the use of oral carbonic anhydrase inhibitors. CONCLUSION: Dorzolamide twice daily was effective and well tolerated by the patients in these studies as adjunctive therapy to timolol. The larger study demonstrated that both concentrations of dorzolamide produce similar IOP-lowering effects to 2% pilocarpine.

A six-week dose-response study of the ocular hypotensive effect of dorzolamide with a one-year extension. Dorzolamide Dose-Response Study Group.

PURPOSE: To investigate the efficacy and dose-response relationship of three concentrations (0.2%, 0.7%, and 2.0%) of dorzolamide hydrochloride in lowering elevated intraocular pressure (IOP) in patients during a six-week period and to evaluate the efficacy of 0.7% and 2.0% dorzolamide administered for an additional year. METHODS: This prospective, double-masked, randomized, placebo-controlled, multinational study enrolled 333 adults with open-angle glaucoma or ocular hypertension. During the six-week dose-response phase, patients were randomized to thrice-daily dosing of four treatments: 0.2%, 0.7%, or 2.0% dorzolamide or placebo (vehicle of dorzolamide). During a one-year extension, patients received 0.7% or 2.0% dorzolamide, and, if needed, 0.5% timolol twice daily for elevated IOP. RESULTS: In the dose-response phase, mean percent reduction of IOP (peak) was 16% to 18% for 2.0% and 0.7% dorzolamide and 4% to 7% for the placebo group, for a net reduction of IOP by dorzolamide of 11% to 14%. The 0.2% concentration of dorzolamide was not sufficiently active for further consideration. During the extension, dorzolamide maintained an adequate reduction of IOP in 55% (174 of 316) of patients. Throughout the study, the reduction in IOP was numerically greater for patients receiving 2.0% vs 0.7% dorzolamide. After 12 months of receiving dorzolamide, 20% to 28% of total carbonic anhydrase activity was observed. CONCLUSIONS: Topical dorzolamide used three times daily in concentrations of 0.7% or 2.0% lowered IOP and was generally well tolerated as monotherapy or in combination with 0.5% timolol.

A double-masked, randomized 1-year study comparing dorzolamide (Trusopt), timolol, and betaxolol. International Dorzolamide Study Group.

OBJECTIVE: To investigate the safety profile and efficacy of 2.0% dorzolamide hydrochloride, when administered three times daily for up to 1 year, compared with that of 0.5% timolol maleate and 0.5% betaxolol hydrochloride, each administered twice daily. In addition, the effect of adding dorzolamide to the regimen of patients with inadequate ocular hypotensive efficacy while they were receiving one of the two beta-adrenoceptor antagonists and the effect of adding timolol to the regimen of patients receiving dorzolamide were also evaluated. DESIGN: A double-masked, randomized, parallel comparison. SETTING: Multinational study at 34 international sites. PATIENTS: Five hundred twenty-three patients with open-angle glaucoma or ocular hypertension, 17 to 85 years of age. Patients currently using ocular hypotensive medications were required to undergo a washout. INTERVENTION: Two percent dorzolamide three times a day, 0.5% timolol (Timoptic, Merck, Whitehouse Station, NJ) twice daily, and 0.5% betaxolol solution (Betoptic, Alcon, Fort Worth, Tex) twice daily. RESULTS: At 1 year, the mean percent reduction in intraocular pressure at peak of 2% dorzolamide, 0.5% timolol, and 0.5% betaxolol was approximately 23%, 25%, and 21%, respectively. At afternoon trough, the mean percent reduction in intraocular pressure was 17%, 20%, and 15% for dorzolamide, timolol, and betaxolol, respectively. CONCLUSIONS: The ocular hypotensive efficacy of 2.0% dorzolamide, given three times a day, is comparable with that of 0.5% betaxolol, given twice daily, for up to 1 year. In addition, long-term use of dorzolamide was not associated with clinically meaningful electrolyte disturbances or systemic side effects commonly observed with the use of oral carbonic anhydrase inhibitors.

Efficacy of twice daily doses of 40 or 20 milligrams famotidine or 150 milligrams ranitidine for treatment of patients with moderate to severe erosive esophagitis. Famotidine Erosive Esophagitis Study Group.

The comparative efficacy of twice daily regimens of 40 mg famotidine (group 1), 20 mg famotidine (group 2), and 150 mg ranitidine (group 3) was investigated in a double-blind randomized study of parallel groups of patients with endoscopically documented erosive esophagitis. Patients were enrolled at 29 centers in 19 countries and treated for 6 to 12 weeks until healing, defined as complete resolution of visible ulceration or erosion of the esophageal mucosa, demonstrated by repeat endoscopy. Healing occurred in 71% of 175 group-1 patients, 68% of 93 group-2 patients, and 60% of 172 group-3 patients; the difference between groups 1 and 3 was significant (P < or = 0.05). The three treatments produced similar levels of global symptomatic improvement and relief of daytime and nighttime heartburn. All treatments were well tolerated. These results support the hypothesis that reduction of esophageal acid exposure by 40 mg famotidine twice daily produces healing of lesions in patients with erosive esophagitis and is more effective than regimens that provide lesser reductions in esophageal acid exposure time.