| RESONIUM CALCIUM |
|Calcium Polystyrene Sulfonate |
|Ion Exchange Resin |
|Action And Clinical Pharmacology: Calcium polystyrene sulfonate is a cation exchange resin prepared in the calcium phase. Each gram of resin has a theoretical in vitro exchange capacity of about 1.3 to 2 mmol of potassium. In vivo, the actual amount of potassium bound will be less than this. The sodium content of the resin is less than 1 mg/g. The calcium content is 1.6 to 2.4 mmol/g. The resin is insoluble in water. Calcium polystyrene sulfonate is not absorbed from the gastrointestinal tract.
Calcium polystyrene sulfonate acts by a cumulative process throughout the gastrointestinal tract, removing potassium ions which are carried away in the feces.
As the resin passes through the colon, it comes into contact with fluids containing increasing amounts of potassium. Whereas in the cecum the concentration of Naand Kare similar to those in the small intestine, in the stool water of the sigmoid colon there may be 6 to 38 mmol/L sodium and 14 to 44 mmol/L potassium. The result is that potassium is taken up in increasing amounts in exchange for calcium ions. The length of time the resin remains in the body is a decisive factor in its effectiveness. For this reason oral administration is more effective than the use of enemas which should, if possible, be retained for 9 hours. The efficiency of potassium exchange is unpredictably variable. The resin is not selective for potassium.
Indications And Clinical Uses: In patients with hyperkalemia associated with anuria or severe oliguria to reduce serum levels of potassium and to remove excess potassium from the body. Calcium polystyrene sulfonate is indicated in all states of hyperkalemia due to acute and chronic renal failure; for example following abortion, complicated labor, incompatible blood transfusion, crush injury, prostatectomy, severe burns, surgical shock, and in cases of severe glomerulonephritis and pyelonephritis.
Calcium polystyrene sulfonate can also be useful in patients requiring dialysis. Serum potassium levels in acute renal failure often reach dangerous heights before a rise in blood urea indicates the need for hemodialysis. Calcium polystyrene sulfonate can be used to reduce these potassium levels and thereby postpone the need for the use of the artificial kidney machine until other causes make it necessary.
Patients on regular hemodialysis therapy may develop shunt difficulties and underdialysis occurs, resulting in serious hyperkalemia. In these circumstances it is advisable to give the resin to control hyperkalemia during the period of underdialysis, monitoring serum potassium and calcium levels at regular intervals.
When patients on routine hemodialysis present a dietary management problem and tend towards hyperkalemia, calcium polystyrene sulfonate can be used to control blood potassium levels. Similarly, patients on prolonged peritoneal dialysis may develop intermittent hyperkalemia after a few weeks, possibly due to dietary problems. These patients also can be satisfactorily controlled with calcium polystyrene sulfonate.
Contra-Indications: Should not be administered to patients with: serum potassium <5 mmol/L; conditions associated with hypercalcemia (e.g., hyperparathyroidism, multiple myeloma, sarcoidosis or metastic carcinoma); a history of hypersensitivity to polystyrene sulfonate resins; obstructive bowel disease.
Oral administration of calcium polystyrene sulfonate is contraindicated in neonates. Administration of the resin in neonates with reduced gut motility (postoperatively or drug induced) is contraindicated.
Manufacturers' Warnings In Clinical States: In neonates, calcium polystyrene sulfonate should not be given by the oral route.
Rare instances of colonic necrosis and intestinal obstruction have been reported with sodium polystyrene sulfonate due to concretion formation. This appears to be related to the use of a sorbitol enema with either inadequate or no lavage after use of the resin.
Precautions: The possibility of severe potassium depletion should be considered and adequate biochemical control, by daily estimation of serum electrolytes and blood urea levels, is essential during treatment. To prevent serious hypokalemia, administration of the resin should be discontinued as soon as the serum potassium level falls to 5 mmol/L to prevent serious hypokalemia. Hypercalcemia has been reported in well dialyzed patients receiving calcium resin, and in the occasional patient with chronic renal failure. Serum calcium levels should be estimated at weekly intervals to detect the early development of hypercalcemia, and the dose of administered calcium resin reduced to levels at which hypercalcemia and hypokalemia are prevented.
Like all cation-exchange resins, calcium polystyrene sulfonate is not totally selective for potassium. Hypomagnesemia and/or hypercalcemia may occur. Accordingly, patients should be monitored for all applicable electrolyte disturbances.
In the event of clinically significant constipation, treatment with the resin should be discontinued until normal bowel motions are resumed. Magnesium-containing laxatives should not be used (see Drug Interactions).
The patient should be positioned carefully when ingesting the resin, to avoid aspiration, which may lead to bronchopulmonary complications.
Children: In both children and neonates, particular care should be observed with rectal administration, as excessive dosage or inadequate dilution could result in impaction of the resin.
Drug Interactions: Digitalis: The toxic effects of digitalis on the heart, especially various ventricular arrhythmia and A-V nodal dissociation, are likely to be exaggerated by hypokalemia, even in the face of serum digoxin concentrations in the 'normal range'.
Cation Donating Agents: These may reduce the effectiveness of the resin in binding potassium.
Nonabsorbable Cation-donating Antacids and Laxatives: Systemic alkalosis has been reported after cation-exchange resins were administered orally in combination with nonabsorbable cation-donating antacids and laxatives such as magnesium hydroxide and aluminum.
Aluminum Hydroxide: Intestinal obstruction due to concretions of aluminum hydroxide has been reported when aluminum hydroxide was combined with the resin (sodium form).
Sorbitol in enemas: (see Warnings).
Pregnancy and Lactation: Calcium polystyrene sulfonate is not absorbed from the gastrointestinal tract. No data are available about the use of polystyrene sulfonate resins in human pregnancy and lactation.
Adverse Reactions: In accordance with its pharmacological actions, calcium polystyrene sulfonate may give rise to hypokalemia and hypercalcemia and their related clinical manifestations (see Overdose: Symptoms and Treatment).
Intestinal intolerance due to the gritty consistency and bulk of the resin may be manifested by the appearance of general adverse effects including nausea, vomiting, gastric irritation, anorexia, constipation and occasionally, diarrhea. These adverse effects may be relieved by intermittent therapy and the use of mild laxatives where constipation is a factor.
Fecal impaction following rectal administration in children, and gastrointestinal concretions following oral administration to neonates, have been reported. Rarely intestinal obstruction has been reported. This could possibly be a reflection of coexisting pathology or inadequate dilution of the resin.
Some cases of acute bronchitis and/or bronchopneumonia associated with inhalation of particles of calcium polystyrene sulfonate have been described.
Symptoms And Treatment Of Overdose: Symptoms: Biochemical disturbances resulting from overdosage may give rise to clinical signs and symptoms of hypokalemia, including irritability, confusion, delayed thought processes, muscle weakness, hyperreflexia, and eventually frank paralysis. Apnea may be a serious consequence of this progression. ECG changes may be consistent with hypokalemia or hypercalcemia; cardiac arrhythmia may occur. tag_Treatment
Treatment: Appropriate measures should be taken to correct serum electrolytes (potassium, calcium). The resin should be removed from the alimentary tract by appropriate use of laxatives or enemas.
Dosage And Administration: Treatment with the resin should be given as soon as the serum potassium level rises above 6 mmol/L (23.5 mg/100 mL). The action may be delayed for 1 or 2 days since maximal exchange probably takes place in the colon. Exchange will continue until all the resin has been voided (this may be 1 or 2 days after administration has been discontinued). For this reason, resin therapy should be stopped when the serum potassium level has fallen to 5 mmol/L, or the continued action may lead to potassium depletion. The following doses are suggested only as a general guide. The precise daily dose should be decided on the basis of regular serum electrolyte determination.
The amount of potassium taken up by the resin will be largely determined by the length of time it is exposed to the high potassium concentration in the fecal water in the colon. For this reason, a tendency towards constipation should be encouraged and purgative drugs should be avoided.
Adults: For adults the usual dose is 15 g, 3 or 4 times a day. The resin is given by mouth in a little water, or it may be made into a paste with some sweetened vehicle, but not orange juice or other fruit juices that are known to contain potassium. The amount of fluid usually ranges from 3 to 4 mL/g of resin. If there is difficulty with swallowing, it may be given through a gastric tube, 2 to 3 mm in diameter.
In cases where vomiting may make oral administration difficult, or in patients who have upper gastrointestinal problems, including paralytic ileus, the resin may be given rectally as a suspension of 30 g resin in 100 mL of 2% methylcellulose and 100 mL of water, as a daily retention enema. In the initial stages, administration by this route as well as orally may help to achieve a more rapid lowering of the serum potassium level.
The rectal route is less effective than the oral, and since the longer the resin is retained the greater is the amount of potassium removed, the enema should, if possible, be retained for at least 9 hours. If both routes are used initially, it is probably unnecessary to continue rectal administration once the oral resin has reached the rectum.
Children: Acute hyperkalemia: Children should be given 1 g/kg body weight of calcium polystyrene sulfonate daily in divided doses. In maintenance therapy the dose may be reduced to 0.5 g/kg body weight daily in divided doses.
Calcium polystyrene sulfonate should be given orally, preferably with a drink or a little jam or honey. It should not be given in fruit drinks and some carbonated beverages, since these have a high potassium content. When the resin is refused by mouth, it may be given rectally suspended in a proportional amount of 10% dextrose in water, using a dose at least as great as that which whould have been given orally. It should not be given in fruit drinks and some carbonated beverages, since these have a high potassium content. Following retention of the enema, the colon should be irrigated to ensure adequate removal of the resin.
Neonates: Oral administration of calcium polystyrene sulfonate is contraindicated in neonates. Administration of the resin in neonates with reduced gut motility (postoperatively or drug induced) is contraindicated. Only rectal administration should be considered. With rectal administration, the minimum effective dosage within the range of 0.5 to 1 g/kg should be employed, diluted as for adults and with adequate irrigation to ensure recovery of the resin. It should not be given in fruit drinks and some carbonated beverages, since these have a high potassium content.
Availability And Storage: Each polystyrene pack contains: 300 g of the flavored calcium polystyrene sulfonate powdered resin. Also contains saccharin and vanillin. Sodium: <1 mmol (1 mg)/g. Alcohol-, gluten-, lactose-, parabens-, starch-, sucrose-, sulfite- and tartrazine-free. A plastic measure is included which holds 15 g of resin.