Nondepolarizing Neuromuscular Blockers include- Pipercuranium, Vecuronium,Doxacuranium, Tobocurane, Mivacuranium,Rocuronium, Cisatracurarium, Atracurarium,Pancuronium Refer- Pancuronium

Drug interactions - summary 

+ Doxacurium - 

Antibiotics-                                                                                                                         may enhance the neuromuscular blocking action of nondepolarizing agents 

Carbamazepine/ Phenytoin-                                                                                  carbamazepine and phenytoin lengthen the the time of onset of  neuromuscular block induced by doxacurium and shorten the duration of the block 

Inhalational anesthetics-                                                                                                  isoflurane, enflurane and halothane decrease the ED50 of  doxacurium by 30 to 45% and prolong the duration of action by upto 25%. 

Lithium/Local anesthetics  agents/ Magnesium salts/ Procainamide/ Quinidine-            may enhance the neuromuscular blocking action of nondepolarizing agents 

Most frequent adverse effect is the extension of the pharmacological action beyond the time needed for surgery and anesthesia. Hypotension, flushing, ventricular fibrilation, myocardial infarction. Bronchosapsm, wheezing.

Cardiovascular- hypotension, flushing, ventricular fibrillation, myocardial infarction, Dermatologic- urticaria, injection at site reaction Respiratory- bronchospasm, wheezing

Special senses- diplopia Miscellaneous- difficult neuromuscular block revesal, prolonged drug effect, fever

Hypersens to the drug

Special precaution:

Neuromuscular disease- neuromuscular blocking agents may have a profounf efect in patients with neuromuscular disease ( eg, myasthenic syndrome).

In these and other conditions in which prolonged neuromuscular block is a possiblity (eg. carcinomatis ) use a pripheral nerve stimulator and a small test dose of doxacurium to assess the level of neuromuscular block and to monitor dosage requirements. Shorter acting muscle relaxants may be more suitable.

Burn victims

resistence to nondepolarizing neuromuscular blocking agents may develop in patients with burns depending upon the time elapsed since the injury and the size of the burn. Acid-base or serum electrolyte abnormalites- may potentiate or antagonisethe action of neuromuscular blocking agents.

Their action may be enhanced by magnesium salts administered for the management of eclampsia or preeclampsia.

Obesity

administratin of doxacurium on the basis of actual body weight is assiciated with a prolonged duration of action in obese patients. Base the dose upon the ideal body weight in obese patients. Malignant hyperthermia- doxacuraium has been studied in MH -susceptible patients.Because MH can develop in the absence of established triggering agents, be prepared to recongnize and treat MH in any patient receiving general anesthesia.

Long term use

information on the use of doxacurium in the ICU is limited. Monitor neuromuscular transmission continously Warnings- Antagonism of neuromuscular block- antagonists (such as neostigmine ) should not be be administered prior to the demonstration of some spontaneous recovery from neuromuscular block.

The time of recovery of neuromuscular function following administration of neostigmine is dependent upon the residual neuromuscular block at the time of attempted reversal, longer recovery times may be anticipated when neostigmine is administered at more profound levels of block.

Renal/hepatic function impairment- consider the possibility of prolonged neuromuscular block in patiens undergoing renal transplantation, and the possibility of a variable onset and duration of neuromuscular block in patients undergoing liver transplantation when doxacrium is used.

Elderly- in elderly patients, the onset of maximum block is slower and the duration of neuromuscular block is more variable and may be longer than in young patients.

Pregnancy- use during pregnancy only if the potential benefit justifies the potential risk to the fetus. Lactation- excercise caution following administration to a nursing woman.

Children- doxacurium has not been studied inchildren < 2 years of age.

Approved by FDA in MArch 1991

Indicaton:

Adjunct to general anesthesia Dosage: For IV use only. Dosing requirements are variable. obese patients 30% more than the ideal body weight. Elderly/renal function impairment- rediced dose.

Overdosage

Symptoms Extended skeletal muscle weakness, decreased respiratory reserve, lower tidal volume, prolonged apnea, cardiovascular collapse and sudden release of histamine. sufficiently excessive doses of nondepolarizing muscle relaxants have no antidote.

Treatment

1. A peripheral nerve stimulator may be used to assesss the degree of residual neuromuscular blockade .

2. For residual neuromuscular blockade with respiratory paralysis or inadequate ventilation, maintain airway and administer manual or mechanical ventilation. 

Missed dose

1. If you miss a dose of this medicine, take it as soon as possible.

2. However, if it is almost time for next dose, skip the missed dose and go back to your regular dosing schedule.

3. Do not double doses.

Pharmacology:

Doxacurium chloride is a long acting, nondepolarizing skeletal muscle relaxent for IV administration. It binds competively to cholinergic receptors onnthe motor end-plate to antagonise the action of acetylcholine, resulting in a block of neuromuscular transmission.

Pregnancy

Use during pregnancy only if the potential benefit justifies the potential risk to the fetus. Lactation

Excercise caution following administration to a nursing woman.

Children

Doxacurium has not been studied in children < 2 years of age.