• A Comparative Study of the Quality of Diltiazem and Verapamil Manufactured in Mexico Versus Those Manufactured in the United States

      Mayersohn, Michael; Yau, Andrew; College of Pharmacy, The University of Arizona (The University of Arizona., 2005)
      Objective: To determine whether or not the amount of active ingredient and content uniformity of diltiazem and verapamil products manufactured in Mexico are comparable to those manufactured in the U.S. Methods: High-performance liquid chromatography (HPLC) assay was used to compare the quantity of active ingredients contained in diltiazem 120 mg ER capsules and verapamil 120 mg ER tablets manufactured in Mexico vs. those manufactured in the United States. The content uniformity was also compared using guidelines contained in the U.S. Pharmacopoeia-National Formulary (USP- NF), with guidelines slightly modified to better suit the experiment. The acceptable range of variances in the quantity of active ingredient was taken from the USP-NF (90-110%). The mean active drug content from the samples manufactured in the U.S. was assumed to meet USP-NF standards at 100%. Results: The experimental results showed that the Mexican verapamil 120 mg ER capsules fell below the USP-NF acceptable range of 90-110% with a value of 83.2%, which is 11.2% less than the U.S. samples tested. The content uniformity of Mexican verapamil also fell below the USP-NF acceptable range of 90-110% with a value of 88.6%. The Mexican diltiazem 120 mg ER capsules fell above the USP-NF acceptable range of 90-110% with a value of 196.2%. The content uniformity was also above the acceptable range with a value of 183.0%. Conclusion: The results of this study showed that the drugs used in this experiment are not within the range that is deemed acceptable by USP-NF standards. The Mexican verapamil was below the range deemed acceptable while the Mexican diltiazem was above the range deemed acceptable. However, the study results cannot be generalized since they represent only a limited number of batches.
    • A Comparative Study of the Quality of Lorazepam and Phenytoin Manufactured in Mexico and the United States

      Mayersohn, Michael; Pak, Chang; College of Pharmacy, The University of Arizona (The University of Arizona., 2005)
      Objectives: To determine whether the quantity of active ingredient and content uniformity of lorazepam and phenytoin manufactured in Mexico is comparable with those manufactured in the United States. Methods: A high-performance liquid chromatography (HPLC) assay based on slightly modified United States Pharmacopoeia- National Formulary (USP-NF) guidelines was used. Relative quantification of the active ingredient was accomplished using the US products as standards. The US products were assumed to contain 100% of the active ingredient. Lorazepam 1mg tablets and phenytoin 100mg capsules were tested using the assays. Results: The quantity of active ingredient in the Mexican lorazepam 1mg tablets were within the acceptable range of the USP-NF guidelines at 100%. The content uniformity was also within the acceptable range of the USP-NF guidelines at 104.6%. The quantity of active ingredient in the Mexican phenytoin 100mg capsules as well as content uniformity were also within the acceptable range of the USP-NF guidelines at 101.6% and 98.2%, respectively. Implications: The results of this study showed that lorazepam and phenytoin manufactured in Mexico were comparable to those manufactured in the US with no significant differences regarding amount of active ingredient and content uniformity.
    • A Comparison of Content and Quality of Atenolol and Captopril Manufactured in Mexico and the United States

      Mayersohn, Michael; Newkirk, Alicia; College of Pharmacy, The University of Arizona (The University of Arizona., 2005)
      Objectives: To determine whether the quantity of active ingredient and content uniformity of atenolol and captopril manufactured in Mexico are comparable with those manufactured in the United States. Methods: An adapted United States Pharmacopoeia-National Formulary (USP-NF) guideline was utilized for a high-performance liquid chromatography (HPLC) assay to quantify the active ingredient of each medication. The US products were considered to contain 100% of the active ingredient, with acceptable variance range of 90-110%. Atenolol 50 milligrams (mg) and captopril 50 mg tablets, manufactured from either Mexico or US, were tested in this comparative study. Results: Quantification of active ingredient in Mexican captopril 50 mg tablets were within the acceptable range of the USP-NF guidelines at 94.2%. The content uniformity was also within the acceptable range of the USP-NF guidelines at 99.0%. The quantity of active ingredient in the Mexican atenolol 50 mg tablets, as well as content uniformity, was also within the acceptable range of the USP-NF guidelines at 110.0% and 95.0%, respectively. Implications: The results of this study showed that captopril and atenolol manufactured in Mexico were comparable to those manufactured in the US with no significant differences regarding amount of active ingredient and content uniformity.
    • Comparison of Content and Uniformity of American versus Mexican Manufactured Acyclovir and Cephalexin

      Mayersohn, Michael; Nii, Sarah; College of Pharmacy, The University of Arizona (The University of Arizona., 2005)
      Objectives: To determine whether acyclovir and cephalexin produced in Mexico are equivalent in content and uniformity to products made in the United States. Methods: High-pressure liquid chromatography (HPLC) assays were performed on drug samples of Mexican products and U.S. products using U.S. Pharmacopeia – National Formulary (USP-NF) guidelines.5 Content and content uniformity of the products from the U.S. and Mexico were compared. Results: Acyclovir produced in Mexico had 75.4% content and 78.1% content uniformity compared to the acyclovir produced in the United States. The Mexican manufactured cephalexin had 99.0% content and 99.9% content uniformity compared to the U.S. manufactured cephalexin. Implications: Not all Mexican manufactured drugs are equivalent in content and content uniformity to American manufactured drugs.
    • Content and Uniformity of Mexican Manufactured Lovastatin and Warfarin Versus American Manufactured Lovastatin and Warfarin

      Mayersohn, Michael; Choiniere, Jennifer; College of Pharmacy, The University of Arizona (The University of Arizona., 2005)
      Objective: To analyze the quantity of active ingredient as well as the content uniformity of lovastatin and warfarin manufactured in Mexico as compared to the lovastatin and warfarin manufactured in the United States. Methods: High-pressure liquid chromatography assays modified from the U.S. Pharmacopoeia will be used to evaluate the amount of active ingredient found in lovastatin and warfarin manufactured in Mexico and America. Area-under-the-curve analysis was done to evaluate relative quantities of the active ingredients. Results: The amount of lovastatin found in the Mexican manufactured product was found to be 64%, and content uniformity was found to be 73%, both values are outside of the acceptable range of 90%-110% set by the USP-NF guidelines. The amount of warfarin found in the Mexican manufactured product was found to be 84% with a content uniformity of 100%. The average content value is outside of the acceptable range of 90%-110% set by the USP-NF guidelines. Conclusion: The results of this study showed that the amounts of active ingredients found in Mexican manufactured lovastatin and warfarin were significantly different from the amounts found in the American manufactured products.
    • THE CONTINUUM OF DROUGHT IN WESTERN NORTH AMERICA

      Cole, Julia E.; Ault, Toby R.; Overpeck, Jonathan T.; Russell, Joellen L.; Betancourt, Julio L.; Evans, Michael N.; Otto-Bliesner, Bette (The University of Arizona., 2011)
      The continuum of western North American hydroclimate during the last millennium is analyzed here using instrumental records, proxy data, and global climate model (GCM) simulations. We find that variance at long timescales (low frequencies) is generally more substantial than variance at short timescales (high frequencies). We find that local sources of autocorrelation (e.g., soil moisture storage) likely explain the tendency for variance to increase from monthly to interannual timescales, but that variance at longer timescales requires remote climate sources of variability. Our analysis of global climate model data indicates that at least one fully coupled GCM can reproduce the characteristics of the continuum on short (interannual) and long (multicentury) timescales, but that proxy spectra and GCM spectra disagree about the amount of variance present on intermediate (decadal to centennial) timescales. Since instrumental records, as well as multiple independent types of paleoclimate records, provide evidence that variance increases with timescale at these frequencies, and because numerical experiments indicate that local autocorrelation is not a likely source of variance at these timescales, we argue that climate model simulations underestimate the full range of low-frequency drought variability. Moreover, the models may also underestimate the risk of future megadroughts, which we attempt to quantify using a new method that combines frequency information from observational data with projections of 21st century hydroclimate. Our results indicate that the risk of a severe, decadal-scale drought during the coming century is at least 1-in-10 for most of the US Southwest, and may be as high as 1-in-3. These findings should be incorporated into adaptation and mitigation strategies to cope with regional climate variability and climate change.
    • Stratigraphy and Sedimentology of the Bisbee Group in the Whetstone Mountains, Pima and Cochise Counties, Southeastern Arizona

      Dickinson, W. R.; Archibald, Lawrence Eben; Schreiber, Joseph F., Jr.; Flessa, Karl; Archibald, Lawrence Eben (The University of Arizona., 1982)
      The Aptian-Santonian(?) Bisbee Group in the Whetstone Mountains comprises 2375 m of clastic sedimentary rocks and limestones. The basal Glance Conglomerate unconformably overlies the Pennsylvanian-Permian Naco Group. It consists of limestone conglomerates which were deposited in proximal alluvial fan environments. The superadjacent Willow Canyon Formation contains finer grained rocks which were deposited in the distal portions of alluvial fans. The lacustrine limestones in the Apache Canyon Formation interfinger with and overlie these alluvial fan facies. The overlying Shellenberger Canyon Formation is composed mostly of terrigenous rocks derived from westerly terranes. This formation contains thick sequences of fluvio-deltaic facies as well as a thin interval of estuarine deposits which mark a northwestern extension of the marine transgression in the Bisbee -Chihuahua Embayment. The youngest formation (Upper Cretaceous?) in the Bisbee Group, the Turney Ranch Formation, consists of interbedded sandstones and marls which were deposited by fluvial and marine(?) processes.