Drugs online research references
Am J Hosp Pharm. 1990 Feb;47(2):369-73.
Sorption of various drugs in polyvinyl chloride, glass, and polyethylene-lined infusion containers.
Martens HJ, De Goede PN, Van Loenen AC.
Department of Pharmacy, Free University Hospital, Amsterdam, The Netherlands.
The sorption of chloroquine sulfate, diazepam, isosorbide dinitrate, lorazepam, midazolam, nitroglycerin, promethazine hydrochloride, thiopental sodium, and warfarin sodium to three types of containers was studied. Appropriate amounts of the drugs were added to 500 mL of 0.9% sodium chloride injection in polyvinyl chloride (PVC) bags, glass bottles, and Clear-Flex bags composed of a laminate of polyethylene, nylon, and polypropylene. The containers were stored in the dark at room temperature for 24 hours. Samples were taken at various intervals and assayed for drug concentration by high-performance liquid chromatography. There were no appreciable changes in pH after 24 hours, and all the admixtures remained clear and colorless. The potency of chloroquine sulfate, lorazepam, midazolam, promethazine hydrochloride, and thiopental sodium remained unchanged in glass, PVC, and Clear-Flex containers. Diazepam, isosorbide dinitrate, nitroglycerin, and warfarin sodium did not show any sorption to glass bottles and Clear-Flex bags. In PVC bags, however, up to 55% of diazepam, 23% of isosorbide dinitrate, 51% of nitroglycerin, and 24% of warfarin sodium was lost during the 24-hour study period. Diazepam, isosorbide dinitrate, nitroglycerin, and warfarin sodium in 0.9% sodium chloride injection showed a loss of potency when stored in PVC containers for 24 hours at room temperature, but none of the drugs studied lost potency when stored in glass bottles and Clear-Flex bags.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=2309728&dopt=Abstract
J Membr Biol. 1987;96(2):121-8.
Evidence for the involvement of calmodulin in the operation of Ca-activated K channels in mouse fibroblasts.
Okada Y, Yada T, Ohno-Shosaku T, Oiki S.
The oscillation of membrane potential in fibroblastic L cells is known to result from periodic stimulation of Ca2+-activated K+ channels due to the oscillatory increase in the intracellular Ca2+ concentration. These repeated hyperpolarizations were inhibited by putative calmodulin antagonists, trifluoperazine (TFP), N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide (W-7) and promethazine (PMZ), and the concentrations required for half-maximal inhibition were 25, 30 and 300 microM, respectively. These doses were lower than those for reducing the membrane resistance due to nonspecific cell damages. Another calmodulin antagonist, chlorpromazine (CPZ), was also effective, but CPZ-sulfoxide was not. Intracellular pressure injections of calmodulin-interacting divalent cations, Ca2+, Sr2+, Mn2+ and Ni2+, elicited slow hyperpolarizations, whereas Mg2+ and Ba2+, which are known to be essentially inert for calmodulin, failed to evoke any responses. The injection of purified calmodulin also brought about a similar hyperpolarization. Quinine, an inhibitor of Ca2+-activated K+ channels, abolished both Ca2+- and calmodulin-induced hyperpolarizations. TFP prevented Ca2+-induced hyperpolarizations. The TFP effect was partially reversed by the calmodulin injection. It is concluded that calmodulin is involved in the operation of Ca2+-activated K+ channels in fibroblasts.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=2439690&dopt=Abstract
Acta Endocrinol (Copenh). 1987 Oct;116(2):241-6.
Calcium-binding proteins and insulin release. Differential effects of phenothiazines on first- and second-phase secretion and on islet cAMP response to glucose.
Krausz Y, Eylon L, Cerasi E.
Department of Endocrinology and Metabolism, Hebrew University Hadassah Medical Centre, Jerusalem, Israel.
Calcium and cAMP are interdependent regulators of glucose-induced insulin release. In the present study we investigated the importance of cAMP and calcium-binding proteins for biphasic insulin secretion by assessing the effects of two phenothiazines known to block such proteins, trifluoroperazine (TFP) and promethazine (PMZ). In isolated rat islets, during 60-min incubations with 16.7 mmol/l glucose both agents inhibited the insulin response with ID50 values of 15 mumol/l for TFP and 5 mumol/l for PMZ. Both agents decreased the maximal insulin response without gross changes in the islet sensitivity to glucose. TFP (15 mumol/l), whereas inducing 50% inhibition of second-phase insulin release, totally suppressed the cAMP response to glucose and the accompanying first-phase insulin secretion (5-min incubations); these effects of TFP could be partially reversed by isobutyl methylxanthine (IBMX). In contrast, 5 mumol/l PMZ, which produced 60% inhibition of second-phase insulin release, had no effect on first-phase insulin and cAMP responses to glucose. Furthermore, IBMX did not modify the inhibitory effect of PMZ on second-phase insulin secretion. The following is concluded: 1. TFP acts preferentially on first-phase insulin release and inhibits cAMP formation; this suggests that calmodulin plays a major role in mediating the initial glucose effect on secretion via stimulation of cAMP. 2. The islet probably contains calcium-sensitive proteins other than calmodulin, since the low concentrations of PMZ shown to inhibit second-phase insulin release lack effects on calmodulin. Synexin could be such a protein.(ABSTRACT TRUNCATED AT 250 WORDS)
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=2444058&dopt=Abstract
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