Potassium plasma levels

Although the cardiac side effects are considerably reduced, metabolic effects occur under the therapy with this /32-sympathomimetics increased plasma levels of free fatty acids, glucose and ketones. In diabetic patients a hyperglycaemic ketoacidosis can be induced. All /32-sympathomimetics reduce the potassium plasma level. 

Laboratory Sodium and potassium plasma levels, hepatic functions, blood gas analysis... 

Van der Molen EJ, Baars AJ, de Graff GJ, Jager LP, Comparative study of the effect of carbadox, olaquindox and cyadox on aldosterone, sodium and potassium plasma levels in weaned pigs, Res. Vet. Sci. 1989 47 11-16. 

Biochemical characteristics (plasma levels of alanine and aspartate transminases, alkaline phosphatase, triglycerides, cholesterol, urea, uric acid, allantoin, glucose, protein, albumin, sodium, potassium, calcium, magnesium, phosphorus urine levels of protein and glucose). 

However, although high potassium concentration was thought essential in early experimental work (Acquatella etcd., 1972), Fuller and Pe (1976) reported that potassium concentrations much higher than normal plasma levels led to poor renal function. A number of more recent studies have claimed that solutions containing high concentrations of sodium ions were equally or even more effective than those with high potassium (Moen et al., 1989 Sumimoto etal., 1989 Marshall etal., 1991). 

Repaglinide en nateglinide are not sulfonylurea agents but their mechanism of action is very alike. Repaglinide is the first carbamoylmethyl-benzoic acid derivative that has been registred for the treatment of diabetes mellitus. It closes ATP-dependent potassium channels in the beta cell membrane with consequent depolarization, opening of calcium channels and increased insulin release. It is rapidly absorbed with peak plasma levels after 1 hour. It has a protein binding of over 98%. 

In addition to the angiotensin II effects, aldosterone secretion is regulated by increased plasma potassium levels.75,83 Presumably, elevated plasma potassium serves as a stimulus to increase aldosterone release, thus causing increased potassium excretion and a return to normal plasma levels. Finally, there is evidence that ACTH may also play a role in aldosterone release. Although ACTH is primarily involved in controlling glucocorticoid secretion, this hormone may also stimulate mineralocorticoid release to some extent.75... 

The occurrence of cardiac toxicity was closely correlated with terfenadine use, and subsequent in vitro studies confirmed that terfenadine (but not fexofenadine) efficiently blocks cardiac potassium channels (14). A study in healthy volunteers treated concomitantly with terfenadine and ketoconazole found a linear relationship between trough terfenadine concentrations and QTC intervals. The QTC interval lengthened up to 110 millisecond at the highest plasma concentrations of 45 ng/mL (9). Thus, the direct inhibitory effect of terfenadine on cardiac potassium channels results in prolongation of cardiac repolarization, which is a well-known cause of ventricular arrhythmias. In one death in which terfenadine was implicated, plasma level of the drug was 55 ng/mL several hours after the last ingestion of the drug (when it normally should be undetectable). 

Uptake of potassium dichromate was determined in a man who was given 0.8 mg of chromium(VI) in drinking water 5 times each day for 17 days (Paustenbach et al. 1996). Steady-state concentrations of chromium in blood were attained after 7 days. Red blood cell and plasma levels returned to background levels within a few days after exposure was stopped. The data are consistent with a bioavailability of 2% and a plasma elimination half-life of 36 hours. 

Uniphyllin Continus 200 mg bd Theophylline normally used after a trial of short and long-acting bronchodilators. Needs plasma levels monitored. Increased risk of low potassium when given with prednisolone and bumetanide. 

An adult contains about 3 g of potassium. The plasma level is maintained within narrow limits by the kidney which can efficiently conserve or excrete potassium according to need. Abnormally low plasma levels cause muscle irritability and weakness together with potentially dangerous cardiac arrhythmias. Similar changes can also occur with abnormally high plasma potassium levels, thus making potassium determination one of the more important investigations in clinical medicine. 

Problems in water and salt nutrition can occur with severe and prolonged diarrhea or vomiting and with prolonged eKercise. Chronic changes in salt nutrition can change blood pressure and influence the course of cardiovascular disease. These nutritional concerns are addressed after first discussing normal plasma levels of sodium and potassium. 

Approximately 75% of patients develop hypokalemia during the course of treatment with AmB [37] However, a need for potassium supplementation to maintain a normal plasma level of potassium can be... 

Urinary potassium and magnesium losses are anticipated consequences of AmB therapy. Some of the losses can be compensated for with increased dietary intake, while others will require oral or intravenous replacement. It should be recognized that the serum levels of these ions do not necessarily correlate with the total deficit, as the plasma levels tend to be conserved while cellular stores are becoming depleted. In general, potassium and magnesium supplements should be given to all patients and the amounts increased if the... 

Plasma levels of calcium and phosphate generally reflect periods of rapid bone growth, which occur in the neonatal and juvenile ages they later show a gradual decline with age. Some age-related variations of sodium potassium and chloride in mice and rats have been reported (Nachbaur et al. 1977 Frith, Suber, and Umholtz... 

Nachbaur, J., M. R. Clarke, J-P. Provost, and J. L. Dancla. 1977. Variations of sodium, potassium and chloride plasma levels in the rat with age and sex. Laboratory Animal Science 27 972-975. 

Numerous methods and data have been published for the collection of blood from rats and mice (Riley 1960 Upton and Morgan 1975 Cardy and Warner 1979 Eowler, Brown, and Elower 1980 Archer and Riley 1981 Cochetto and Bjornsson 1983 Neptun, Smith, and Irons 1985 Suber and Kodell 1985 Conybeare et al. 1988 Dameron et al. 1992 Itumi et al. 1993 Matsuzawa et al. 1994 Bernard et al. 1996 Walter 1999 Mahl et al. 2000 Nahas et al. 2000 Schnell et al. 2002). Values obtained from major blood vessels or cardiac puncture are less variable than those samples taken from the tail or retro-orbital plexus this may be in part due to contamination with tissue fluid. Potassium, total protein, and several enzymes are higher in samples collected from the tail or the retro-orbital plexus. The use of carbon dioxide and, to a lesser extent, halothane increases plasma levels of glucose, potassium, and inorganic phosphate. 

Quinidine and thiazide diuretics can both enhance the toxicity of digitalis. The action of quini-dine is attributed to phtirmacokinetic mechanisms, especially inhibition of its clearance. The plasma concentration of digoxin predictably increases when quinidine is added. The enhancement of digitalis toxicity by thiazides is due to a pharmacodynamic mechanism, namely, the action of these diuretics to reduce extracellular potassium. Sulfasalazine decreases plasma levels of digitalis by interfering with gut absorption of the drug. The answer is (D). 

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