Which IV calcium: chloride or gluconate?
From the May 7,1997 Issue
Problem: Some hospitals store both calcium gluconate
and calcium chloride in floor stock, in automated dispensing
modules or in emergency kits. There is a three-fold difference
in the primary cation between calcium gluconate, which contains
4.65 mEq Ca++/gram, and calcium chloride, which contains 13.6
mEq Ca++/gram. When ordering IV calcium, this difference has
important implications. Calcium chloride is more irritating
when given IV. Confusion may also occur in ordering intramuscular
calcium. Calcium chloride is extremely irritating and should
never be given IM.1 Since intravenous calcium is often ordered
without specifying which salt is desired (e.g., gluconate
or chloride), the implications of storing these alongside
one another in patient care areas are obvious.
Serum phosphorus levels are important to consider when replacing
calcium. If serum phosphate is elevated during IV calcium
administration, precipitation of calcium phosphate may occur
in the vasculature with potential end organ injury such as
interstitial pneumonitis.2 When serum phosphorus is low, larger
quantities of calcium may be needed for replacement. Levels
of calcium and phosphorus must be carefully monitored. Specific
problems reported with calcium include:
- Interactions with digoxin - rapid injection of calcium
may cause bradyarrhythmias, especially in patients on digoxin.3
- Antagonism of calcium channel blockers resulting in blood
- Extravasation causing tissue necrosis.
Incorrect calcium to phosphate ratios (which are dependent
upon the order of mixing, the mixing process, phosphate content
of the amino acid solution, volume at time calcium is added,
and pH) could lead to precipitation and end organ injury or
death.4 Precipitation may be impossible to detect visually
when the TPN is mixed with lipids.
Safe Practice Recommendation: The Institute for Safe
Medication Practices and the Institute for Healthcare Improvement
in Boston are preparing a document about high hazard medications.
The following recommendations are made to reduce adverse drug
events with calcium:
- Reduce available options: Use either calcium gluconate
or calcium chloride in an institution, but not both.
- To avoid calcium phosphate precipitation, prepare solutions
containing calcium and phosphorus only in the pharmacy,
using standard protocols. Avoid mixing with lipids because
visible precipitation will be obscured.
- 1. Standardize ordering: calcium should be ordered based
on the number of mEq of calcium. Calcium should never be
ordered by number of "amps" or "mLs." The salt should always
- Standardize administration: Develop a standard administration
protocol including rules for rate of administration and
monitoring of calcium, phosphate and albumin levels prior
To monitor safe use of calcium salts, ISMP and IHI recommend
measuring the percentage of times IV calcium use is deemed
to have been administered in accordance with standards. Intermittently
review a sample of cases where IV calcium was administered.
[D, N, P]
Reference: 1. Lacy C, Armstrong LL, Naomi
Ingrim, Lance LL, 4th ed. Drug Information Handbook. 4th ed.
Hudson: Lexi-Comp. 1996. 2. Knowles JB et al. Pulmonary deposition
of calcium phosphate crystals as a complication of home total
parenteral nutrition. JPEN 1989;13:209-13. 3. Facts and Comparisons.
St. Louis:Wolters Kluwer;1997. 4. FDA Safety Alert, April