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| AHFS/Drugs.com | Monograph |
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| Routes of administration | Intravenous |
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| Pharmacokinetic data | |
| Bioavailability | NA |
| Protein binding | 77 to 91% |
| Metabolism | Hepatic |
| Eliminationhalf-life | 1.5 to 2.7 hours |
| Excretion | Renal and biliary |
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| CompTox Dashboard(EPA) | |
| ECHA InfoCard | 100.035.923 |
| Chemical and physical data | |
| Formula | C35H60N2O4 |
| Molar mass | 572.875 g·mol−1 |
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Pancuronium (trademarked asPavulon) is anaminosteroidmuscle relaxant with various medical uses.[1] It is used ineuthanasia and is used in some states as the second of three drugs administered duringlethal injections in the United States.
Pancuronium is a typicalnon-depolarizingcurare-mimeticmuscle relaxant. Itcompetitively inhibits thenicotinic acetylcholine receptor at theneuromuscular junction by blocking the binding ofacetylcholine. It has slightvagolytic activity, causing an increase in heart rate, but noganglioplegic (i.e., blockingganglions) activity. It is a very potent muscle relaxant drug, with anED95 (i.e., the dose that causes 95% depression of muscle twitch response) of only 60 μg/kg body weight. Onset of action is relatively slow compared to other similar drugs, in part due to its low dose: an intubating dose takes 3–6 minutes for full effect. Clinical effects (muscle activity lower than 25% of physiological) last for about 100 minutes. The time needed for full (over 90% muscle activity) recovery after single administration is about 120–180 minutes in healthy adults.
The effects of pancuronium can be at least partially reversed byanticholinesterasics, such asneostigmine,pyridostigmine, andedrophonium.
Workers atOrganon were inspired by the structure of the aminosteroid alkaloidmalouetine to develop a series of aminosteroid neuromuscular blockers based on anandrostane nucleus, culminating in the development of pancuronium bromide.[2][3][4]
Pancuronium is designed to mimic the action of two molecules ofacetylcholine with the quaternary nitrogen atoms spaced rigidly apart by the steroid rings at a distance of ten atoms (interonium distance).Decamethonium andsuxamethonium also have this same interonium distance.
Pancuronium is used withgeneral anesthesia in surgery for muscle relaxation and as an aid tointubation or ventilation. It does not havesedative oranalgesic effects.
Side-effects include moderately raisedheart rate and therebyarterial pressure and cardiac output, excessivesalivation,apnea andrespiratory depression,rashes,flushing, andsweating.[medical citation needed] The muscular relaxation can be dangerous in the seriously ill and it can accumulate leading to extended weakness. Pancuronium is not preferable in long-term use in ICU-ventilated patients.
InBelgium and theNetherlands, pancuronium is recommended in the protocol foreuthanasia. After administeringsodium thiopental to induce coma, pancuronium is delivered in order to stop breathing.[5]
Pancuronium is also used as one component of alethal injection in administration of thedeath penalty in some parts of theUnited States.[6]
Like all non-depolarising muscle relaxants, pancuronium has no effect on level of consciousness. Therefore, if theanaesthetic used is insufficient, the individual may be awake but unable to cry out or move due to the effect of the pancuronium. There have been several civil lawsuits alleging similar failures of adequate anaesthesia during general surgical procedures. These have been largely due to improper or insufficient dosages of anaesthetic in concert with normal dosages of muscle relaxants such as pancuronium.
In 2007, Michael Munro, a Scottishneonatologist atAberdeen Maternity Hospital, was cleared of malpractice by theGeneral Medical Council Fitness to Practice panel after giving 23 times the standard dose of pancuronium to two dyingneonates. Terminally ill, both dying babies were suffering fromagonal gasping and violent body spasms, which was highly distressing for the parents to witness. Munro then administered pancuronium to the babies after advising the parents that this would ease their suffering and could also hasten death.[7][8] It was on record that neither of the children's parents were unhappy with Munro's treatment.[9]
Amnesty International has objected to its use in lethal injections on the grounds that it "may mask the condemned prisoner's suffering during the execution,"[10] thereby leading observers to conclude that lethal injection is painless, or lesscruel than other forms of execution.
The United Kingdom bans the export of pancuronium bromide to the United States due to its use in lethal injections, but not to the Netherlands or Belgium.[11]
Pancuronium was used inEfren Saldivar's killing spree.[12] It was also used by theSkin Hunters to kill patients in thePolish city ofŁódź. Pavulon was also used byRichard Angelo in 1987 to kill at least ten patients under his care at theGood Samaritan Hospital in New York.