Sugammadex is the first clinical representative of a new class of drugs called selec­tive relaxant binding agents. It has revolutionized the way anesthesiologists think about drug reversal. Sugammadex selectively binds rocuronium or vecuronium, thereby reversing their neuromuscular blocking action. Due to its 1:1 binding of rocuronium or vecuronium, it is able to reverse any depth of neuromuscular block. Because of its pharmacodynamic profile, sugammadex, in combination with rocuronium, may have the potential to displace succinylcholine as the “gold standard” muscle relaxant for rapid sequence induction.
Muscle relaxants are routinely used worldwide as part of a modern concept of balanced anesthesia. Commonly preferred nondepolarizing muscle relax­ants have very few adverse effects (mostly allergic reactions) during anesthesia ,however a residual duration of action of muscle relaxants beyond the end of the operation, also referred to as postoperative residual curarization, is a well-known problem. Postoperative residual curarization can lead to respiratory insufficiency, impaired upper airway func­tion, and increased risk of aspiration  and consequently, of the risk of postoperative pulmonary complications. To avoid postoperative residual curarization and its complications anaesthesiologists use cholinesterase inhibitor, e.g. neostigmine. This antagonism, however, has shortcomings. Cholinesterase inhibitors can therefore only be used if the neuromuscular function has already recovered to a certain degree.  Also as cholinesterase inhibitors act, not only at the neu­romuscular junction, but also, in the parasympathetic system, they have numerous unwanted side effects, eg, bradycardia, hypotension, and                                  
bronchoconstriction. Thus, they are typically combined with a muscarinic            antagonist (parasympatholytic drug), such as glycopyrrolate or atropine which are known to cause tachycardia, dry mouth and urinary retention. Thus , with the invention of sugammadex, a completely new possibility of neuromuscular block reversal was introduced to anesthesia practice. Sugammadex was approved for clinical use in Europe, in 2008 and in Japan, in 2010. Approval in the US by the Food and drug Administration (FDA) is pending.
Pharmacology
Molecular characteristics
Sugammadex is a modified γ-cyclodextrin specifically designed to encapsulate the muscle relaxant rocuronium. γ-cyclodextrins are cyclic oligosaccharide carbohydrates made up of eight sugar molecules obtained from the degradation of starch. γ-cyclodextrin is a hydrophilic molecule with a lipo­philic core that can encapsulate other lipophilic, preferably steroidal molecules. γ-cyclodextrins therefore have aqueous solubility, with the ability to bind lipophilic drugs. Although the eight identical hydroxyl side chains of sugammadex were specifically designed to bind rocuronium, the other steroidal muscle relaxants, vecuronium and pancuronium, are also bound by sugammadex, albeit with a lesser affinity .
Pharmacokinetics
When sugammadex is intravenously injected (central compartment), it immediately binds free intravascular rocuronium. This leads to a concentration gradient, which shifts rocuronium from the peripheral compartment (includ­ing the effect compartment, ie, the neuromuscular junction) towards the central compartment, where it is also encapsu­lated by sugammadex. This rapidly restores neuromuscular and muscle function. A higher sugammadex dose is therefore more effective to lower the free rocuronium concentration in the plasma than a lower one.
The elimination half-life of sugammadex is approximately 100−150 minutes. It is not metabolized in the body and is nearly 100% cleared by the kidneys. As a result, special consideration must be given to patients with renal failure.
Clinical use/dosage
Depending on the muscle relaxant used and the depth of the neuromuscular block at the time of reversal, different sugam­madex doses are recommended. The recommended dose-range is 2–16 mg/kg/  depending on the level of block. The doses should be able to accelerate the speed of recovery from the neuromuscular block to a TOF ratio of 0.9 in an average of 3 minutes. The different doses for rocuronium are summarized in Table 1.

 The sugammadex doses to reverse a deep (posttetanic count of 1−2) or a moderate (TOF count of 2) vecuronium-induced neuromuscular block are the same as for rocuronium; how­ever, due to the lower affinity, the speed of recovery from the neuromuscular block is slightly slower
                                            Specific indications
1.Sugammadex as acute therapeutic option in the event of an allergic reaction against rocuronium
An allergic reaction to rocuronium is one of the most common causes of anaphylaxis in anesthesia. The clinical appearance can range from a flush to cardiocirculatory arrest with the need for cardiopulmonary resuscitation. The exact incidence rate can only be estimated and varies from country to country. Since sugammadex binds rocuronium, it has been speculated that it can be used in an allergic reaction to rocuronium, to ameliorate the allergic cascade and subsequent symptoms.
2. Rapid sequence induction (RSI) and “cannot intubate, cannot ventilate” situations
Until now, succinylcholine has been the “gold standard” muscle relaxant for rapid sequence induction (RSI), due to its fast time of onset and short duration of action. However, succinylcholine has numerous contraindications and unwanted side effects, such as hyperkalemia, myalgia, and rhabdomyolysis. Rocuronium has been shown to be an alternative, with identical intubation conditions when used in appropriate doses (1.2 mg/kg).A drawback to the use of a three- to fourfold effective dose (ED95) of rocuronium is a long duration of action, which could potentially endanger the patient in a “can’t intubate, can’t ventilate” situation. With the availability of sugammadex, the use of succinylcholine, with all its potential hazards, seems unnecessary. Several studies have shown that the rocuronium−sugammadex combination works as fast as succinylcholine regarding onset and recovery time. This has also been supported by a Cochrane review that showed that the rocuronium−sugammadex combination to be potentially safer than succinylcholine.
3.Cesarean section
When general anesthesia is given to patients receiving a Cesarean section, a rapid sequence technique is used, as pregnant women are not considered to be nil per os. As stated above, the use of 1.2 mg/kg rocuronium to facilitate endotracheal intubation is equally effective as 1 mg/kg succinylcholine. Rocuronium has not shown untoward effects on the neonates, if the neuromuscular block is reversed with sugammadex, this would occur after the baby is deliv­ered, when the woman is no longer pregnant. This regimen therefore seems a possible alternative that should be further investigated.
4. Electroconvulsive therapy
Electroconvulsive therapy (ECT) is another special indication for RSI. General anesthesia with complete muscle relax­ation is mandatory for ECT, however, a treatment session only lasts several minutes. Succinylcholine is the preferred muscle relaxant for ECT for the same reasons as mentioned previously regarding succinylcholine and RSI. However, the combination of rocuronium and sugammadex is a promising new clinical alternative
5. Myasthenia gravis and other specific myopathies
The use of muscle relaxants in patients with muscular and neuromuscular diseases is challenging due to the altered sensitivity towards muscle relaxants, preexisting muscle weakness due to the myopathy itself, and also, the possible use of cholinesterase inhibitors as medication. Nonetheless, muscle relaxants should not be avoided in these patients if they require endotracheal intubation. The new strategy of muscle relaxant reversal using sugammadex seems to be a safe and reliable option in these patients. Six case reports in patients with myasthenia gravis document the successful use of sugammadex.
Safety
1.The most clinically relevant common side effects (2%) of sugammadex are due to the fast recovery of the muscle function during balanced anesthesia, which might unmask a too light anesthesia. In such cases, the patient might cough, move, grimace, or suckle on the endotracheal tube.
2. QT-Prolongation
3. Of clinical concern is the possible reoccurrence of neuro­muscular block. In 2% of the patients in the Phase I−III trials, neuromuscular block deepened again after it had initially recovered. However, all patients with reoccurrence had not received the adequate dose of sugammadex, ie, they had received less than the recommended dose. In these patients, the redistribution of rocuronium from the peripheral com­partment to the central (intravascular) compartment led to a second redistribution into the effect compartment (neuromuscular junction). Consequently a high and safe dose of sugammadex should be given. For purely safety reasons, the manufacturer recommends 4 mg/kg sugammadex.
To  summarize , Sugammadex is a potent, fast, and safe reversal agent for aminosteroid muscle relaxants and has the potential to change anesthesia practice. It has revolutionized the way anesthe­siologists think about drug reversal and pharmaceutical dose−response control. It also has the potential to eliminate succinylcholine from anesthesia practice. However, the price of the drug and the missing evidence of cost efficacy has led to a limited use in clinical anesthesia so far. Even though there are no obvious safety concerns in the relatively small number of subjects who have been given the drug, but exposure to a much larger population is required before a definitive safety profile can be drawn. A question that remains is where will sugammadex fit,  into or alter, clinical practice?
Further Reading

1. Murphy GS, Szokol JW, Marymont JH, Greenberg SB, Avram MJ, Vender JS. Residual neuromuscular blockade and critical respiratory events in the postanesthesia care unit. Anesth Analg. 2008;107(1):130–137.
2. Bom A, Hope F, Rutherford S, Thomson K. Preclinical pharmacology of sugammadex. J Crit Care. 2009;24(1):29–35.
3. Akha AS, Rosa J, Jahr JS, Li A, Kiai K. Sugammadex: cyclodextrins, development of selective binding agents, pharmacology, clinical devel­opment, and future directions. Anesthesiol Clin. 2010;28(4):691–708
4. Duvaldestin P, Kuizenga K, Saldien V, et al. A randomized, dose-response study of sugammadex given for the reversal of deep rocuronium- or vecuronium-induced neuromuscular blockade under sevoflurane anes­thesia. Anesth Analg. 2010;110(1):74–82.
5. de Boer HD, Driessen JJ, Marcus MA, Kerkkamp H, Heeringa M, Klimek M. Reversal of rocuronium-induced (1.2 mg/kg) profound neuromuscular block by sugammadex: a multicenter, dose-finding and safety study. Anesthesiology. 2007;107(2):239–244.
6. Suy K, Morias K, Cammu G, et al. Effective reversal of moder­ate rocuronium- or vecuronium-induced neuromuscular block with sugammadex, a selective relaxant binding agent. Anesthesiology. 2007;106(2):283–288.
7. Pongrácz A, Szatmári S, Nemes R, Fülesdi B, Tassonyi E. Reversal of Neuromuscular Blockade with Sugammadex at the Reappear­ance of Four Twitches to Train-of-four Stimulation. Anesthesiology. 2013;119(1):36–42.
8. Baldo BA, McDonnell NJ, Pham NH. Drug-specific cyclodextrins with emphasis on sugammadex, the neuromuscular blocker rocuronium and perioperative anaphylaxis: implications for drug allergy. Clin Exp Allergy. 2011;41(12):1663–1678.
9. Perry JJ, Lee JS, Sillberg VA, Wells GA. Rocuronium versus succi­nylcholine for rapid sequence induction intubation [review]. Cochrane Database Syst Rev. 2008;2:CD002788
10. McCahon R. Role of sugammadex in rapid sequence induction and intubation. Br J Anaesth. 2012;109(1):123; author reply 123–124.
11. Abrishami A, Ho J, Wong J, Yin L, Chung F. Sugammadex, a selective reversal medication for preventing postoperative residual neuromuscular blockade [review]. Cochrane Database Syst Rev. 2009;4:CD007362
12. Unterbuchner C, Fink H, Blobner M. The use of sugammadex in a patient with myasthenia gravis. Anaesthesia. 2010;65(3):302–305.
13. Rudzka-Nowak A, Piechota M. Anaesthetic management of a patient with myasthenia gravis for abdominal surgery using sugammadex. Arch Med Sci. 2011;7(2):361–364.