Evaluation of a potential clinical interaction between ceftriaxone and calcium.
ABSTRACT In April 2009, the FDA retracted a warning asserting that ceftriaxone and intravenous calcium products should not be coadministered to any patient to prevent precipitation events leading to end-organ damage. Following that announcement, we sought to evaluate if the retraction was justified. A search of the FDA Adverse Event Reporting System was conducted to identify any ceftriaxone-calcium interactions that resulted in serious adverse drug events. Ceftazidime-calcium was used as a comparator agent. One hundred four events with ceftriaxone-calcium and 99 events with ceftazidime-calcium were identified. Adverse drug events were recorded according to the listed description of drug involvement (primary or secondary suspect) and were interpreted as probable, possible, unlikely, or unrelated. For ceftriaxone-calcium-related adverse events, 7.7% and 20.2% of the events were classified as probable and possible for embolism, respectively. Ceftazidime-calcium resulted in fewer probable embolic events (4%) but more possible embolic events (30.3%). Among cases that considered ceftriaxone or ceftazidime and calcium as the primary or secondary drug, one case was classified as a probable embolic event. That patient received ceftriaxone-calcium and died, although an attribution of causality was not possible. Our analysis suggests a lack of support for the occurrence of ceftriaxone-calcium precipitation events in adults. The results of the current analysis reinforce the revised FDA recommendations suggesting that patients >28 days old may receive ceftriaxone and calcium sequentially and provide a transparent and reproducible methodology for such evaluations.
- SourceAvailable from: aop.sagepub.com[Show abstract] [Hide abstract]
ABSTRACT: BACKGROUND:Critically ill patients often receive multiple medications via continuous intravenous infusion. Coadministration of multiple medications through the same port of a venous access device often is necessary but requires an assessment of compatibility.OBJECTIVE:To describe the frequency of inappropriate coadministration of continuously infused medications via a Y-site and the use of intravenous catheters in patients in Canadian intensive care units (ICUs) in a multicenter, cross-sectional observational study.METHODS:Data pertaining to medication compatibility via Y-site infusion (medication combinations known to be incompatible or not known to be compatible), frequency of specific medications administered via continuous infusion, and catheter use (median number, location, and types of venous catheters) were collected from medical records of 434 patients in the ICUs of 13 teaching hospitals in Canada.RESULTS:Forty-six percent of patients were receiving 2 or more medication infusions simultaneously. Forty episodes of inappropriate coadministration of these infusions were identified in 37 patients. The prevalence of inappropriate coadministration of drugs via a Y-site port in all patients was 8.5% (95% CI 5.8-11.2). The prevalence of incompatible combinations via Y-site in patients with 2 or more medication infusions was 18.7%. Twenty-five of these 37 patients could have had their drug schedules rearranged into acceptable combinations, leaving 12 patients who would have required additional intravenous access to facilitate appropriate medication infusions. Median (range) number of central and peripheral venous access devices inserted per patient were 1 (0-4) and 1 (0-5), respectively. Seventeen of 95 patients with 2 or more central venous catheters could have had their medication infusions rearranged to render 1 catheter idle.CONCLUSIONS:Inappropriate Y-site combinations of medications continuously infused in Canadian ICUs are common. Management of medication infusions could, however, have been optimized in most of these situations.Annals of Pharmacotherapy 04/2013; · 2.57 Impact Factor
Article: Biotic acts of antibiotics.[Show abstract] [Hide abstract]
ABSTRACT: Biological functions of antibiotics are not limited to killing. The most likely function of antibiotics in natural microbial ecosystems is signaling. Does this signaling function of antibiotics also extend to the eukaryotic - in particular mammalian - cells? In this review, the host modulating properties of three classes of antibiotics (macrolides, tetracyclines, and β-lactams) will be briefly discussed. Antibiotics can be effective in treatment of a broad spectrum of diseases and pathological conditions other than those of infectious etiology and, in this capacity, may find widespread applications beyond the intended antimicrobial use. This use, however, should not compromise the primary function antibiotics are used for. The biological background for this inter-kingdom signaling is also discussed.Frontiers in Microbiology 01/2013; 4:241.
- [Show abstract] [Hide abstract]
ABSTRACT: INTRODUCTION: In 1998, a multidisciplinary team of investigators initiated the Research on Adverse Drug events And Reports (RADAR) project, a post-marketing surveillance effort that systematically investigates and disseminates information describing serious and previously unrecognized serious adverse drug and device reactions (sADRs). OBJECTIVE: Herein, we describe the findings, dissemination efforts, and lessons learned from the first decade of the RADAR project. METHODS: After identifying serious and unexpected clinical events suitable for further investigation, RADAR collaborators derived case information from physician queries, published and unpublished clinical trials, case reports, US FDA databases and manufacturer sales figures. STUDY SELECTION: All major RADAR publications from 1998 to the present are included in this analysis. DATA EXTRACTION: For each RADAR publication, data were abstracted on data source, correlative basic science findings, dissemination and resultant safety information. RESULTS: RADAR investigators reported 43 serious ADRs. Data sources included case reports (17 sADRs), registries (5 sADRs), referral centers (8 sADRs) and clinical trial reports (13 sADRs). Correlative basic science findings were reported for ten sADRs. Thirty-seven sADRS were described as published case reports (5 sADRs) or published case-series (32 sADRs). Related safety information was disseminated as warnings or boxed warnings in the package insert (17 sADRs) and/or 'Dear Healthcare Professional' letters (14 sADRs). CONCLUSION: An independent National Institutes of Health-funded post-marketing surveillance programme can supplement existing regulatory and pharmaceutical manufacturer-supported drug safety initiatives.Drug Safety 04/2013; · 3.41 Impact Factor
ANTIMICROBIAL AGENTS AND CHEMOTHERAPY, Apr. 2010, p. 1534–1540
Copyright © 2010, American Society for Microbiology. All Rights Reserved.
Vol. 54, No. 4
Evaluation of a Potential Clinical Interaction between
Ceftriaxone and Calcium?
Emily Steadman,1Dennis W. Raisch,2,3Charles L. Bennett,4,5,6John S. Esterly,7,8Tischa Becker,3
Michael Postelnick,8June M. McKoy,5,6Steve Trifilio,8Paul R. Yarnold,9and Marc H. Scheetz7,8*
Midwestern University Chicago College of Pharmacy, Downers Grove, Illinois1; VA Cooperative Studies Program Clinical Research
Pharmacy, Albuquerque, New Mexico2; University of New Mexico, College of Pharmacy, Albuquerque, New Mexico3;
VA Chicago Healthcare System and VA Center for Management of Complex Chronic Care, Chicago, Illinois4;
Divisions of Hematology/Oncology and Geriatric Medicine, Department of Medicine, Northwestern University
Feinberg School of Medicine, Chicago, Illinois5; Robert H. Lurie Comprehensive Cancer Center, Chicago,
Illinois6; Department of Pharmacy Practice, Midwestern University Chicago College of Pharmacy,
Downers Grove, Illinois7; Department of Pharmacy, Northwestern Memorial Hospital, Chicago,
Illinois8; and Department of Emergency Medicine, Northwestern University Feinberg School of
Medicine, Chicago, Illinois9
Received 5 August 2009/Returned for modification 5 November 2009/Accepted 11 January 2010
In April 2009, the FDA retracted a warning asserting that ceftriaxone and intravenous calcium products
should not be coadministered to any patient to prevent precipitation events leading to end-organ damage.
Following that announcement, we sought to evaluate if the retraction was justified. A search of the FDA Adverse
Event Reporting System was conducted to identify any ceftriaxone-calcium interactions that resulted in serious
adverse drug events. Ceftazidime-calcium was used as a comparator agent. One hundred four events with
ceftriaxone-calcium and 99 events with ceftazidime-calcium were identified. Adverse drug events were recorded
according to the listed description of drug involvement (primary or secondary suspect) and were interpreted
as probable, possible, unlikely, or unrelated. For ceftriaxone-calcium-related adverse events, 7.7% and 20.2%
of the events were classified as probable and possible for embolism, respectively. Ceftazidime-calcium resulted
in fewer probable embolic events (4%) but more possible embolic events (30.3%). Among cases that considered
ceftriaxone or ceftazidime and calcium as the primary or secondary drug, one case was classified as a probable
embolic event. That patient received ceftriaxone-calcium and died, although an attribution of causality was not
possible. Our analysis suggests a lack of support for the occurrence of ceftriaxone-calcium precipitation events
in adults. The results of the current analysis reinforce the revised FDA recommendations suggesting that
patients >28 days old may receive ceftriaxone and calcium sequentially and provide a transparent and
reproducible methodology for such evaluations.
Ceftriaxone (CRO), an expanded-spectrum cephalosporin
approved for use by the United States Food and Drug Admin-
istration (FDA) in 1984 (29), has a wide range of antimicrobial
activity and is currently recommended in the national guide-
lines for the treatment of many community-acquired infec-
tions, including pneumonia and meningitis (12, 13). In Sep-
tember 2007, the FDA issued an Alert to Healthcare
Professionals to revise the U.S. package labeling due to con-
cerns of adverse events (28). Specifically, the warning sug-
gested that CRO and calcium-containing products should not
be coadministered to any patient receiving either agent within
the previous 48 h in order to prevent possible end-organ dam-
age secondary to CRO-calcium precipitation. The FDA warn-
ings were provoked by a report of fatal outcomes in neonates,
in whose lungs and kidneys CRO-calcium precipitates were
discovered (1). However, the majority of these outcomes were
due to a Y-site incompatibility between CRO and calcium
administered simultaneously through the same intravenous
line (28). After a recent analysis of two in vitro studies with
neonatal and adult plasma found no direct correlation between
the potential for a precipitation reaction with various concen-
trations of CRO and calcium, the FDA modified its warning on
14 April 2009 to recommend that CRO and calcium-containing
products may be sequentially administered in patients older
than 28 days if the infusion lines are thoroughly flushed be-
tween infusions with a compatible fluid (24, 28). Such recom-
mendations are now in line with those of the French Health
Products Safety Agency (AFSSAPS) and the World Health
Organization (WHO), which have warned against using CRO
and calcium simultaneously in infants, in whom the adverse
event has been documented; however, neither agency has of-
fered formal recommendations regarding the usage of CRO
and calcium in adults (2), probably due to the lack of CRO-
associated end-organ toxicities caused by calcium-containing
precipitates in adults.
As CRO is widely used in the United States to treat numer-
ous invasive bacterial infections, several authors took interest
in the initial FDA safety warning (10, 22, 23). Since recent
changes have been implemented in the United States on the
basis of data from in vitro studies, vigilant safety monitoring
and clinical analysis can provide the best guidance for the use
of these agents. Hence, we reviewed the available medical
* Corresponding author. Mailing address: Midwestern University
Chicago College of Pharmacy, Department of Pharmacy Practice, 555
31st St., Downers Grove, IL 60515. Phone: (630) 515-6116. Fax: (630)
515-6958. E-mail: firstname.lastname@example.org.
?Published ahead of print on 19 January 2010.
literature for reports of CRO-calcium precipitation in adults
and analyzed the FDA MedWatch Adverse Event Reporting
System (AERS) databases for adverse drug interactions re-
ported with CRO treatment in association with calcium. For
comparison, we also searched AERS for interactions reported
between ceftazidime (CAZ) and calcium.
MATERIALS AND METHODS
Review of the published literature. A literature review was conducted in an
attempt to identify CRO-calcium interactions that resulted in a serious adverse
drug event (ADE) in adults. We reviewed the data available in the public domain
by searching Medline via the PubMed search engine. MeSH search terms were
used for all literature inquiries. The term “ceftriaxone,” “calcium,” or “adverse
events” was combined with the Boolean combiner “AND” in order to match with
the following outcomes: “embolism” or “precipitation.” Full manuscripts were
obtained for all publications that met the inclusion criteria. Manuscripts written
in all languages were considered. The references cited in those publications were
reviewed for relevance and were obtained when applicable.
Adverse Event Reporting System database. FDA’s AERS database was ana-
lyzed by using preferred terms from the Medical Dictionary for Regulatory
Activities (MedDRA), and the time period from 1998 through the second quar-
ter of 2007 was targeted. We chose to use data beginning in 1998 due to the
FDA’s implementation of the AERS database that year, which provided better
consistency in data content and structure. The data extended through the second
quarter of 2007 because that was the last data set available for public use when
we analyzed the AERS data. We identified all ADEs reported in the AERS in
which CRO and calcium or CAZ and calcium were reported in any role (suspect
or concomitant). Age, gender, and event date were used to identify and remove
duplicative reports. The following variables were summarized for all AERS cases
evaluated: preferred MedDRA term, patient age, patient sex, the year of the
report, the reporter’s occupation, the indication for antibiotic treatment, patient
outcome, and the source of the report. The drugs (CAZ, CRO, and calcium)
were categorized according to the reporter’s attribution of causality as primary
suspect, secondary suspect, or concomitant. As reporters could select from any of
the choices, it was assumed that these classifications represented a gradient in the
continuum of the likelihood of drug involvement. Patient outcomes were classi-
fied according to exact AERS reporting terms of death, disabling, hospitaliza-
tion, life threatening, required intervention, or other. Sources comprising com-
pany representatives, health professionals, literature report, foreign study, or
other were reported. Complete data were not available for all cases, and all
percentages are based on the available data. To examine the overall clinical
course of each case and avoid double reporting, we linked follow-up reports back
to the original reports.
Adverse drug event classification. ADEs were assessed for the possibility that
the embolic event caused pulmonary or renal failure. ADEs were classified
according to the National Cancer Institute Cancer Therapy Program Evaluation:
Common Terminology Criteria for Adverse Events (version 3.0; CTCAE) attri-
bution standards: unrelated, unlikely, possible, or probable (19). Definitions
were adapted and utilized as follows: “unrelated” was no renal or pulmonary
involvement. “Unlikely” was renal or pulmonary involvement, but no clear re-
lationship to embolic event was evident (e.g., multisystem organ failure or events
that are likely not to be due to end-organ damage caused by embolic events, such
as with prerenal disease). “Possible” was renal or pulmonary involvement that
could be related to an embolic event. “Probable” was renal or pulmonary in-
volvement that could be related to an embolic event and reporter suggestion of
CRO or CAZ as a primary or secondary drug in combination with calcium as a
primary, secondary, or concomitant drug.
Two authors (M.H.S. and J.S.E.) independently reviewed and classified all
ADEs for the potential of an embolic event causing end-organ failure (renal or
pulmonary failure). Disagreements in classification between the two reviewers
were settled by a third reviewer (M.P.). Majority rule was used for discrepancies
Data analysis and statistical evaluation. Descriptive statistics were calculated
for all study variables. These included the number (n), the mean, the standard
deviation for interval measures, and n and percent for categorical measures.
Bivariate statistical comparisons between patient groups, defined by taking CRO
versus CAZ, were performed by using optimal discriminant analysis (ODA), an
exact nonparametric method that is isomorphic with Fisher’s exact test for binary
data and that identifies the threshold value which specifically maximizes inter-
group discrimination for ordinal values (32). A multivariable model for discrim-
inating these patient groups was obtained by using hierarchically optimal classi-
fication tree analysis, an exact nonparametric method that involves chained
ODAs and that explicitly maximizes model accuracy in predicting class member-
ship status (31, 32).
Published literature. With the exception of biliary sludging
(27) and one case of nephrolithiasis (11), we found no reports
in the primary literature of possible CRO-calcium precipita-
tion or embolic events that resulted in end-organ dysfunction
Adverse Event Reporting System database. Two hundred
three total individual safety reports were identified and evalu-
ated for the occurrence of possible embolism among persons
who received CRO plus calcium or CAZ plus calcium (Table
1). CRO plus calcium was listed as having been received in 104
cases (51%), and CAZ plus calcium was listed as having been
received in 99 cases (49%). Patients ranged in age from new-
born to 94 years. Twenty-two cases involved individuals under
the age of 18 years. The patients were less than 1 year old in
five of these cases. Twenty of the 22 individuals under 18 years
of age had received CAZ. Among all patients, the patients who
had received CAZ had fewer probable embolic events (4%)
but more possible embolic events (30.3%) than the patients
who received CRO, among whom 7.7% of the events were
classified as probable for embolism, while 20.2% of the events
were classified as possible. A total of 18/203 (8.9%) events
were reported with either drug as the primary or the secondary
agent in conjunction with calcium as a primary or a secondary
agent (14 events involving CRO versus 4 events involving
CAZ) (Table 2). Two events occurred in the group that re-
ceived CRO plus calcium and were classified as probable em-
bolic events; one patient ultimately died, although a definitive
assessment of causality was not possible with the limitations of
the data sources. The occurrence of the preferred MedDRA
terms is located in Table 3. Additional cases (n ? 48) listed
CRO (n ? 24) or CAZ (n ? 24) as the primary or secondary
drug and calcium as a concomitant therapy. Of these, six CRO
TABLE 1. Demographics
CRO (n ? 104)CAZ (n ? 99)
Mean (SD) age (yr) 58.6 (19.3)a
No. (%) male 64 (62.7)c
No. (%) of cases with the
following report source:
General source, manufacturer
General source, other
an ? 91.
bn ? 85.
cn ? 102.
dn ? 98.
VOL. 54, 2010POTENTIAL CEFTRIAXONE-CALCIUM ADE 1535
cases and four CAZ cases were classified as probable embolic
events. Four of the six CRO-treated patients died, whereas
none of the CAZ-treated patients died.
Bivariate statistical analysis revealed two statistically reliable
effects. First, the patients in the group treated with CRO were
older (P ? 0.005). While the difference was statistically reli-
able, the associated ESS—a standardized index of classifica-
tion accuracy in which 0 is chance accuracy and 100 is perfect
accuracy—was 25%, reflecting moderate ecological validity
(31, 32). Second, the CRO-treated patients had fewer life-
threatening experiences (P ? 0.004), with the ESS being 18%,
indicating relatively weak ecological validity. Jackknife validity
analysis revealed that both effects are likely to cross-generalize
to an independent random patient sample (32). Other bivari-
ate findings were generally equivocal. Classification tree anal-
ysis additionally identified that among those patients experi-
encing any event (death, disabling, or life-threatening events),
more patients receiving CRO (25/28, 89.3%) than patients
receiving CAZ (21/35, 60%) died (P ? 0.02; ESS ? 42%,
indicating a moderate effect). When the sample was restricted
to patients having a probable or a possible renal or pulmonary
event, Classification tree analysis was unproductive due to an
insufficient statistical power attributable to the small number
of patients experiencing probable or possible renal or pulmo-
We found occasional occurrences of possible or probable
embolic events reported after treatment with either CRO or
CAZ and calcium, likely indicating similar probabilities of em-
bolic events between the drugs. Our assessment was completed
by using a compilation of ADE reports for two similar expanded-
spectrum cephalosporins and concomitant calcium administra-
tion. In fact, we found only 16 incidents in which we deemed
the event to be probably due to a drug interaction (Table 3).
This number is larger than that reported in Table 2, as some
cases involved multiple events. Furthermore, the number of
cases in which an adverse drug event was probably or possibly
related to the use of a drug in combination with calcium was
roughly evenly divided between those receiving CRO (n ? 43)
TABLE 2. Assessment of relationship likelihood and
No. (%) of patients
Cases involving an embolic event
Possible, nonrenal, nonpulmonary
Primary cause by drug
Secondary cause by drug
Concomitant cause by drug
Primary cause by calcium
Secondary cause by calcium
Concomitant cause by calcium
Primary or secondary cause by both
drug and calcium
Concomitant drug and calcium
14 (13.5)19 (19.2)
24 (23.1)24 (24.2)
Patient ultimate disposition with ADE
Death, disabling, or life threatening
Reaction treated with druga
34 (32.7)41 (41.4)
aData were gathered prior to 1998.
TABLE 3. Classification of reported ADEs by drug group and
consensus renal/pulmonary/other embolic phenomena
No. of patients
Probable embolic event
Possible embolic event
Acute respiratory distress syndrome
Increased blood creatinine level
Decreased oxygen saturation
Possible nonrenal, nonpulmonary,
Disseminated intravascular coagulation
aCVA, cerebrovascular accident.
bDVT, deep vein thrombosis.
1536STEADMAN ET AL.ANTIMICROB. AGENTS CHEMOTHER.
and those receiving CAZ (n ? 40) (Table 3). Once again, this
number is higher than that reported in Table 2, for the same
reason noted above. The relatively similar numbers of ADEs
are important, as there is no current concern for a precipita-
tion reaction between CAZ and calcium. Even our probable
events are likely overcalls, as alternative hypotheses for pul-
monary and renal failure exist (e.g., acute interstitial nephritis
with expanded-spectrum cephalosporins), even in the presence
of calcium. We found that when patients experienced dire
outcomes (death or disabling or life-threatening conditions),
more patients in the CRO group died (P ? 0.02); however,
when the analysis was restricted to the more applicable data
(only those with a probable or a possible renal or pulmonary
event), the sample was too small—and the effects were too
weak—to support a productive multivariable analysis. Thus,
our results suggest a low to no incidence of CRO-calcium
embolic events leading to end-organ toxicity in adults.
Others have also recently analyzed the AERS database and
focused specifically on the neonatal population (8). A total of
seven cases were identified among the individuals in this co-
hort, six of which resulted in death. The neonates were 3 weeks
of age or younger in five of these six cases; age was not re-
corded in the sixth report. Many of the neonates received doses
of CRO higher than those recommended in the package insert,
and some of the neonates received the drug via intravenous
push administration, which is not recommended due to the
increased initial serum concentrations that result. Additionally,
none of the seven cases occurred in the United States (8). This
analysis supports the FDA warning that CRO not be used by
neonates (?28 days of age) if they are receiving (or are ex-
pected to receive) calcium-containing intravenous products.
The history of the events leading to the multiple warnings is
complex and can be difficult to follow. The 2007 warning issued
by the FDA emanated from a report generated by the French
National Commission of Pharmacovigilance on 31 January
2006 (1) which detailed fatal outcomes in neonates as a result
of CRO-calcium precipitates in the lungs and kidneys. The
investigation was conducted between 2002 and 2004 by the
Regional Center of Pharmacovigilance (Paris, France) and
combined international laboratory data with regional French
data (Table 4) (1). Ten of 77 regional files and 21 of 247
international files were selected for in-depth reviews. Within
the 10 regional files, one calcium-CRO interaction resulting in
death occurred in a premature infant in 2002. In 2004, one
“favorable outcome” occurred. This outcome was not further
defined, but one can speculate that the patient survived. Ad-
ditionally, there was suspicion of one CRO-acetaminophen
and calcium gluconate interaction (outcome undefined), one
error of administration, and seven cases of lithiasis in six total
patients (two renal events in infants and one in a child, two
biliary events in children, and one case of mixed lithiases).
Within the chosen international reports, newborn reactions
included one case of renal lithiasis, one case of biliary lithiasis,
and two suspected cases of undetermined lithiasis. In the 2- to
18-year-old segment, there were 13 cases of biliary lithiasis, 2
case of renal lithiasis, and 2 cases of mixed lithiases. After the
completion of this initial inquiry, the investigators reviewed
178 additional international cases dating from 1996 to 2001 in
children less than 2 years of age. These data revealed 7 cases of
calcium-CRO interactions, 13 cases of biliary lithiasis, and 7
cases of renal lithiasis (14 of these cases occurred in infants less
than 1 year old, and 8 of these cases were less than 6 months),
as well as 2 deaths due to unknown causes. Of all the lithiases
reviewed by the commission, approximately 75% of the total
cases occurred in children less than 18 years of age (1). The
FDA later stated that it had uncovered three additional fatal-
ities in neonates and concluded that it was necessary to insti-
tute a modification to the labeling of CRO (28). While the
exact sources were unclear, the FDA cited a total of nine cases,
including eight deaths. In five cases, embolic events appeared
to lead to patient demise, with crystalline structures being
identified in three of the cases. In one of these cases, crystalline
emboli were found in both the lungs and the kidneys. The
remaining three cases died as a result of unclear causes (18).
Internationally, the events triggered heterogeneity in guid-
ance. The AFSSAPS and the WHO issued warnings asking
providers to refrain from using CRO and calcium simulta-
neously in infants, although neither agency has offered formal
recommendations regarding their usage in adults. In a Novem-
ber 2006 release, the AFSSAPS indicated that CRO was con-
traindicated in premature infants up to 41 weeks of age and in
term neonates less than age 28 days with hyperbilirubinemia or
concomitant calcium use. Likewise, the latest WHO recom-
mendations mirror the French recommendations (2) (Table 5).
Thus, the majority of recommendations are now focused on
The lack of documented clinical events in adults is supported
by the results of in vitro experiments and calculations. An in
vitro study completed by Roche and the FDA in 2009 evaluated
the recovery of CRO (i.e., the purported precipitation) in
pooled human plasma according to various concentrations of
calcium and CRO (7). Purported precipitation occurred at
lower calcium concentrations for isomorphic CRO concentra-
tions in neonatal plasma than in adult plasma (precipitation
likely at ?16 mg/dl and ?24 mg/dl, respectively). Such results
indicate that there may be differences in the level of protein
TABLE 4. Summary of results by French Commission of Pharmacovigilance on possibility of reaction of CRO and calciuma
No. of patients
Less than 2 yr oldGreater than 2 yr old
aData are from reference 1.
VOL. 54, 2010POTENTIAL CEFTRIAXONE-CALCIUM ADE1537
binding which exacerbate precipitation. One can also consider
the likelihood of precipitation on the basis of the known serum
concentrations of CRO and calcium (Table 6). To estimate
calcium serum concentrations conservatively, a well-stirred
model, as well as zero-order infusion and no distribution (the
total volume is equal to the intravascular volume), was as-
sumed for calcium. Dose calculations for calcium were based
on mg/kg dosing (16) and average weights for age stratifica-
tions for each age group (20). Free calcium concentrations
were used for the calculations (27). The maximal expected
CRO concentrations were obtained from values in the litera-
ture (17, 24, 26). Calculation of the saturation index was based
on the product of the maximal expected serum CRO concen-
tration obtained at steady state (post-distributive phase) and
maximal free calcium concentration (the supraphysiologic con-
centration plus the bolus dose concentration) divided by the
solubility product constant (27). Analysis of these age-stratified
saturation indices reveals that neonates have a saturation index
twofold greater than that for adults (Table 6). The calculations
showing a higher saturation index for neonates as a result of
higher calcium concentrations coupled with the in vitro findings
that precipitation occurs at calcium concentrations ?16 mg/dl
for neonates and ?24 mg/dl for nonneonates suggests that
neonates are at the highest risk for precipitation. The findings
empirically support the presence of CRO-calcium precipita-
tion when conditions are favorable for this outcome and,
hence, support the current FDA contraindication of CRO and
calcium in patients less than 28 days old (24, 28). Additionally,
these data support the retraction of the 2007 FDA warning
(that all age groups not receive CRO and calcium-containing
products within 48 h of one another) (28). One should also
consider that certain variables can make precipitation more
favorable. Pathophysiology, such as dehydration, may dispro-
portionately increase drug and calcium concentrations and
may place neonates at increased risk for precipitation com-
pared to the risk for adults when they are given CRO and
calcium in combination.
The findings of in vivo studies with animals should also be
considered. Supplementary investigations with animals have
provided evidence of precipitation of the calcium salt of CRO
in the gallbladder bile of dogs and baboons; however, the
likelihood of this occurrence in humans is thought to be lower
since CRO in humans has a prolonged half-life compared to
that in the animals studied, the calcium salt of CRO is more
soluble in human bile, and the calcium concentrations in hu-
mans are reduced (24). While the likelihood of precipitation is
lower for humans, the potential for manifestation is not zero
and may be higher in certain scenarios. For example, the col-
lecting tubules of organs that typically function in the clearance
of xenobiotics may experience elevated drug concentrations.
Thus, it is not surprising to observe biliary sludging or neph-
rolithiasis in patients who receive CRO and calcium, as high
concentrations predispose individuals to these conditions (4,
18, 27). In the biliary tract, CRO concentrations are elevated
due to biliary excretion (40% of total elimination); the con-
centrations of CRO can exceed the concentrations measured
in serum by 20 to 150 times (6, 27). Additionally, when CRO is
secreted into bile, a passive flow of calcium ions is induced
(30). In both children and adults, precipitation events are most
often transient and the incidence of lithiasis is ?0.1% (15).
Such events may be more common and predictable in individ-
uals with high concentrations of CRO in the gallbladder due to
fasting or dehydration, as is common in elderly individuals or
individuals with impaired gallbladder emptying (14, 27).
While this phenomenon is predictable in the gallbladder,
precipitation has occurred in the kidneys and lungs of neonates
TABLE 5. Recommendations by governing bodies
Description of guidelines
FDA (28) ......................In 2007, CRO should not be administered within 48 h of administration of calcium-containing products for any patient;
in 2009, CRO and calcium-containing products may be sequentially administered if the infusion lines are thoroughly
flushed between infusions with a compatible fluid for patients greater than 28 days of age
WHO (2).......................Not for use by premature infants until 41 wk of age (gestational age at delivery plus wk after birth); consider
restriction below 1 mo of age since in several situations it is contraindicated in this age group and other alternatives
AFSSAPS (1)................CRO is contraindicated in premature infants until 41 wk of age (gestational age at delivery plus wk after birth) and in
term neonates less than 28 days of age if there is hyperbilirubinemia or if the neonate is receiving calcium
TABLE 6. Calculation of saturation indices
vol (ml/kg) (3)
calcium concn after
(17, 24, 26)
500 mg per dose
2.12 ? 10?6
1.32 ? 10?6
1.04 ? 10?6
1.10 ? 10?6
aExpected calcium concentration assuming the use of a bolus dose of calcium and a well-stirred model with zero-order infusion. The total volume is equal to the
intravascular volume (no distribution).
bCRO doses and concentrations assuming the most aggressive FDA-approved dosing.
1538 STEADMAN ET AL.ANTIMICROB. AGENTS CHEMOTHER.
as embolic phenomena from the circulating blood supply (1,
10, 18, 28). These events might be explained by the possibility
that neonates metabolize CRO differently than adults, since
their biliary secretion pathway is poorly developed, resulting in
elevated serum concentrations (25, 27). A lower total systemic
clearance produces a 100 to 200% longer half-life in infants
than in children and adults (25). Similar precipitation events
could potentially occur in adults, as there are many clinical
scenarios that result in simultaneously high concentrations of
endogenous calcium and administered CRO, such as treat-
ment for superimposed infections in dehydrated adult patients
with elevated serum calcium concentrations. We suggest the
use of caution when the use of sequential therapy is contem-
plated in these scenarios and agree with the labeling that sug-
gests that intravenous therapy with CRO and calcium not be
commenced simultaneously in any patient (9, 24). Thus, in vitro
studies, a systematic analysis of an adverse event reporting
database, and the lack of clinical observations of adverse
events yielding similar results for CRO and CAZ agree that
precipitation events leading to renal or pulmonary compromise
are not likely for most adult patients.
To our knowledge, this study employs the most comprehen-
sive clinical evaluation to date of a possible reaction between
CRO and calcium in patients, although several important lim-
itations exist. First, our study is restricted to reported data
available from the public domain and MedWatch reports.
While all medications prescribed in the United States are sub-
ject to MedWatch reporting, AERS data represent reports that
are voluntary, sporadic, and often incomplete (5). Differences
in the numbers of reports between drugs relate to utilization
rates as well as many other notable limitations. To retain high
sensitivity, we included all reports of CRO or CAZ in conjunc-
tion with calcium for any adverse drug event reported to Med-
Watch. Second, CAZ was used as a comparator of the associ-
ated but likely noncausal precipitation events. While these
methods are nonspecific for the identification of embolic
events, the “noise” created by this mechanism of study is high
in the CAZ group, which signifies that most reactions observed
are probably unrelated to the administration of the drugs in
combination with calcium; this is further emphasized by the
fact that older patients were identified in the CRO-treated
group. Since neonates appear to be the only category of pa-
tients with an embolic event relationship to date, a study mech-
anism with low levels of noise should have identified CRO-
treated patients as younger. Our model lost the ability to
predict outcomes when we restricted the data to those patients
whom we classified as probable or possible renal or pulmonary
events, due to a combination of the small sample size and weak
effects. Hence, either no difference or a very small difference
exists between the two groups. Third, it is also possible that the
reporters may not have considered including calcium products
in their MedWatch reports. Fourth, AERS data do not provide
sufficient information to calculate incidence rates due to the
nature of passive, voluntary reporting to MedWatch and the
lack of a denominator (utilization). Fifth, the methods used to
categorize the likelihood of events attributed to the drug, while
they are systematic, remain subjective. Specifically, our modi-
fied definition of “probable” cannot be interpreted literally, as
it is only closer to causal in a spectrum ranging from unrelated-
associated to causal. Finally, it is possible that clinicians might
have recognized embolic phenomena with CRO and calcium
but were unwilling to report them secondary to eventual fa-
vorable clinical outcomes or time constraints. It has been es-
timated that due to the voluntary, passive surveillance design
of the MedWatch system, ?10% of adverse events are re-
ported to the FDA (21). The inability to distinguish rare from
underreported events underscores the need for improved post-
Conclusions. In conclusion, our evaluation revealed a rela-
tive lack of evidence to support a serum precipitation event
between CRO and calcium in adults. A causal relationship
seems to exist for infants receiving CRO, but these findings
have not been identified in the adult population. Our results
reinforce the new FDA recommendations. Despite this, our
analysis does not exclude the possibility that such an ADE
could exist in adults; a biological gradient appears to be
present, with scenarios that result in supranormal CRO and
calcium concentrations placing recipients at the highest theo-
retical risk. Therefore, we recommend that individuals subject
to intravascular depletion not be given sequential infusions of
CRO and calcium. Continued active surveillance of this poten-
tial ADE, as suggested by the FDA, is prudent.
This study was funded in part by a Midwestern University Chicago
College of Pharmacy (MWU CCP) Student Research grant (Emily
Steadman and Marc H. Scheetz), an MWU CCP Faculty Research
Stimulation grant (Marc H. Scheetz), and the Society of Infectious
Diseases Pharmacists: Infectious Diseases Pharmacotherapy Resi-
dency Award Program (John H. Esterly and Marc H. Scheetz). Addi-
tionally, the following individuals are supported in part by the U.S.
National Cancer Institute: Charles L. Bennett (grant 1R01CA 102713-
01) and June M. McKoy (grant 1K01CA134554-01). None of the other
authors received funding for the preparation or publication of the
We thank Kenneth Knoblauch and Genevie `ve Knoblauch for their
help with translating French government warnings and Shaifali Bhalla
None of us has conflicts of interest to declare.
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