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The most frequent adverse effect of nondepolarizing blocking agents as a class consists of an extension of the pharmacological action beyond the time needed for surgery and anesthesia. This effect may vary from skeletal muscle weakness to profound and prolonged skeletal muscle paralysis resulting in respiratory insufficiency and apnea which require manual or mechanical ventilation until recovery is judged to be clinically adequate (see OVERDOSAGE). Inadequate reversal of neuromuscular block from NUROMAX (doxacurium chloride) is possible, as with all nondepolarizing agents. Prolonged neuromuscular block and inadequate reversal may lead to postoperative complications.

Observed in Clinical Trials

Adverse experiences were uncommon among the 1034 surgical patients and volunteers who received NUROMAX (doxacurium chloride) and other drugs in US clinical studies in the course of a wide variety of procedures conducted during balanced or inhalational anesthesia. The following adverse experiences were reported in patients administered NUROMAX (doxacurium chloride) (all events judged by investigators during the clinical trials to have a possible causal relationship):

Incidence Greater than 1%

None

Incidence Less than 1%

Cardiovascular:* Hypotension,† flushing,† ventricular fibrillation, myocardial infarction
Respiratory: Bronchospasm, wheezing
Dermatological: Urticaria, injection site reaction
Special Senses: Diplopia
Nonspecific: Difficult neuromuscular block reversal, prolonged drug effect, fever
* Reports of ventricular fibrillation (n = 1) and myocardial infarction (n = 1) were limited to ASA Class 3-4 patients undergoing cardiac surgery (n = 142).
† 0.3% incidence. All other reactions unmarked were ≤ 0.1%.

Observed During Clinical Practice

There have been post-marketing reports of severe allergic reactions (anaphylactic and anaphylactoid reactions) with the use of neuromuscular blocking agents of which NUROMAX (doxacurium chloride) is a member. These reactions, in some cases, have been life threatening and fatal. Because these reactions were reported voluntarily from a population of uncertain size, it is not possible to reliably estimate their frequency (see WARNINGS and PRECAUTIONS).