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The safety of Synercid was evaluated in 1099 patients enrolled in 5 comparative clinical trials. Additionally, 4 non-comparative clinical trials (3 prospective and 1 retrospective in design) were conducted in which 1199 patients received Synercid for infections due to Gram-positive pathogens for which no other treatment option was available. In non-comparative trials, the patients were severely ill, often with multiple co-morbidities or physiological impairments, and may have been intolerant to or failed other antibacterial therapies.
Adverse Reaction Summary – All Comparative Studies
Safety data are available from five comparative clinical studies (n= 1099 Synercid; n= 1095 comparator). One of the deaths in the comparative studies was assessed as possibly related to Synercid. The most frequent reasons for discontinuation due to drug-related adverse reactions were as follows:
% of patients discontinuing therapy by reaction type
Clinical Reactions – All Comparative Studies
Adverse reactions with an incidence of ≥ 1% and possibly or probably related to Synercid administration include:
|Adverse Reactions||% of patients with adverse reactions|
|Inflammation at infusion site||42.0||25.0|
|Pain at infusion site||40.0||23.7|
|Edema at infusion site||17.3||9.5|
|Infusion site reaction||13.4||10.1|
Additional adverse reactions that were possibly or probably related to Synercid with an incidence less than 1% within each body system are listed below:
Cardiovascular: palpitation, phlebitis;
Clinical Reactions – Skin And Skin Structure Studies
In two of the five comparative clinical trials Synercid (n=450) and comparator regimens (e.g., oxacillin/vancomycin or cefazolin/vancomycin; n=443) were studied for safety and efficacy in the treatment of complicated skin and skin structure infections. The adverse event profile seen in the Synercid patients in these two studies differed significantly from that seen in the other comparative studies. What follows is safety data from these two studies.
Discontinuation of therapy was most frequently due to the
following drug related events:
|Type||% of patients discontinuing therapy by reaction type|
Venous adverse events were seen predominately in patients who
had peripheral infusions. The most frequently reported venous and non-venous
adverse reactions possibly or probably related to study drug were:
|% of patients with adverse reactions|
|-Pain at infusion site||44.7||17.8|
|-Inflammation at infusion site||38.2||14.7|
|-Edema at infusion site||18.0||7.2|
|-Infusion site reaction||11.6||3.6|
There were eight (1.7%) episodes of thrombus or thrombophlebitis in the Synercid arms and none in the comparator arms.
Laboratory Events-All Comparative Studies
The following table shows the number (%) of patients exhibiting laboratory values above or below the clinically relevant “critical” values during treatment phase (with an incidence of 0.1% or greater in either treatment group).
|Parameter||Critically High or Low Value||Synercid Critically High or Low||Comparator Critically High or Low|
|AST||> 10 x ULN||9 (0.9)||2 (0.2)|
|ALT||> 10 x ULN||4 (0.4)||4 (0.4)|
|Total Bilirubin||> 5 x ULN||9 (0.9)||2 (0.2)|
|Conjugated Bilirubin||> 5 x ULN||29 (3.1)||12 (1.3)|
|LDH||> 5 x ULN||10 (2.6)||8 (2.1)|
|Alk Phosphatase||> 5 x ULN||3 (0.3)||7 (0.7)|
|Gamma-GT||> 10 x ULN||19 (1.9)||10 (1.0)|
|CPK||> 10 x ULN||6 (1.6)||5 (1.4)|
|Creatinine||≥ 440 μmoL/L||1 (0.1)||1 (0.1)|
|BUN||≥ 35.5 mmoL/L||2 (0.3)||9 (1.2)|
|Blood Glucose||> 22.2 mmoL/L||11 (1.3)||11 (1.3)|
|< 2.2 mmoL/L||1 (0.1)||1 (0.1)|
|Bicarbonates||> 40 mmoL/L||2 (0.3)||3 (0.5)|
|< 10 mmoL/L||3 (0.5)||3 (0.5)|
|CO2||> 50 mmoL/L||0 (0.0)||0 (0.0)|
|< 15 mmoL/L||1 (0.2)||0 (0.0)|
|Sodium||> 160 mmoL/L||0 (0.0)||0 (0.0)|
|< 120 mmoL/L||5 (0.5)||3 (0.3)|
|Potassium||> 6.0 mmoL/L||3 (0.3)||6 (0.6)|
|< 2.0 mmoL/L||0 (0.0)||1 (0.1)|
|Hemoglobin||< 8 g/dL||25 (2.6)||16 (1.6)|
|Hematocrit||> 60%||2 (0.2)||0 (0.0)|
|Platelets||> 1,000,000/mm³||2 (0.2)||2 (0.2)|
|< 50,000/mm³||6 (0.6)||7 (0.7)|
Clinical Adverse Reactions
Approximately one-third of patients discontinued therapy in these trials due to adverse events. However, the discontinuation rate due to adverse reactions assessed by the investigator as possibly or probably related to Synercid therapy was approximately 5.0%.
There were three prospectively designed non-comparative
clinical trials in patients (n = 972) treated with Synercid. One of
these studies (301), had more complete documentation than the other two (398A
and 398B). The most common events probably or possibly related to therapy were:
|Adverse Reactions||% of patients with adverse reaction|
|Study 301 Study 398A||Study 398B|
|Arthralgia and Myalgia||7.4 3.3||6.8|
The percentage of patients who experienced severe related arthralgia and myalgia was 3.3% and 3.1%, respectively. The percentage of patients who discontinued treatment due to related arthralgia and myalgia was 2.3% and 1.8%, respectively.
The most frequently observed abnormalities in laboratory studies were in total and conjugated bilirubin, with increases greater than 5 times upper limit of normal, irrespective of relationship to Synercid, reported in 25.0% and 34.6% of patients, respectively. The percentage of patients who discontinued treatment due to increased total and conjugated bilirubin was 2.7% and 2.3%, respectively. Of note, 46.5% and 59.0% of patients had high baseline total and conjugated bilirubin levels before study entry.
Serious adverse reactions in clinical trials, including non-comparative studies, considered possibly or probably related to Synercid administration with an incidence < 0.1% include: acidosis, anaphylactoid reaction, apnea, arrhythmia, bone pain, cerebral hemorrhage, cerebrovascular accident, coagulation disorder, convulsion, dysautonomia, encephalopathy, grand mal convulsion, hemolysis, hemolytic anemia, heart arrest, hepatitis, hypoglycemia, hyponatremia, hypoplastic anemia, hypoventilation, hypovolemia, hypoxia, jaundice, mesenteric arterial occlusion, neck rigidity, neuropathy, pancytopenia, paraplegia, pericardial effusion, pericarditis, respiratory distress syndrome, shock, skin ulcer, supraventricular tachycardia, syncope, tremor, ventricular extrasystoles and ventricular fibrillation. Cases of hypotension and gastrointestinal hemorrhage were reported in less than 0.2% of patients.
Read the Synercid (quinupristin and dalfopristin) Side Effects Center for a complete guide to possible side effects
Iin vitro drug interaction studies have shown that Synercid significantly inhibits cytochrome P450 3A4. (See WARNINGS.)
Synercid does not significantly inhibit human cytochrome P450 1A2, 2A6, 2C9, 2C19, 2D6, or 2E1. Therefore, clinical interactions with drugs metabolized by these cytochrome P450 isoenzymes are not expected.
A drug interaction between Synercid and digoxin cannot be excluded but is unlikely to occur via CYP3A4 enzyme inhibition. Synercid has shown in vitro activity (MICs of 0.25 mcg/mL when tested on two strains) against Eubacterium lentum. Digoxin is metabolized in part by bacteria in the gut and as such, a drug interaction based on Synercid's inhibition of digoxin's gut metabolism (by Eubacterium lentum) may be possible.
Iin vitro combination testing of Synercid with aztreonam, cefotaxime, ciprofloxacin, and gentamicin, against Enterobacteriaceae and Pseudomonas aeruginosa did not show antagonism.
Iin vitro combination testing of Synercid with prototype drugs of the following classes: aminoglycosides (gentamicin),β-lactams (cefepime, ampicillin, and amoxicillin), glycopeptides (vancomycin), quinolones (ciprofloxacin), tetracyclines (doxycycline) and also chloramphenicol against enterococci and staphylococci did not show antagonism.
Read the Synercid Drug Interactions Center for a complete guide to possible interactions
Last reviewed on RxList: 11/9/2016
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