OA11758A

OA11758A - Regulation of anaesthesia.

Info

Publication number: OA11758A
Application number: OA1200100203A
Authority: OA
Inventors: Michael Alkire; Jim Fallon; Richard Haier; Christopher John Doug Pomfrett
Original assignee: Univ Manchester
Priority date: 1999-02-05
Filing date: 2000-02-01
Publication date: 2005-07-19
Also published as: NO20013795L; JP2002536337A; KR20010101992A; TR200102265T2; CN1346278A; ID30518A; WO2000045832A2; AP2001002245A0; NO20013795D0; WO2000045832A3; IL144572A0; MXPA01007949A; BR0008046A; EP1148887A2; AU2445900A; CA2360124A1

Abstract

The present invention concerns uses of compounds which modulate Delta-Sleep Inducing Peptide active for regulating anaesthesia and methods of evaluating the anaesthetic needs of a subject comprising assaying a sample taken from the subject for the presence of Delta-Sleep Inducing Peptide.

Description

1 ”758

REGULATION OF ANAESTHESIA

The présent invention relates to the régulation of anaesthesia and also amethod of evaluating the anaesthetic needs of a subject.

The metabolic activity of the brain changes in various clinical situations. Forexample the metabolic activity of the brain is increased during an epileptic fit andduring rapid eye movement sleep. In contrast the metabolic activity of the brain isreduced during hibernation and during the administration of a general anaesthetic.

Anaesthesia may be defmed as a loss of feeling or insensibility to extemalstimuli. Anaesthesia may be local (the loss of sensation in a spécifie tissue) or general(when it is generally associated with a lack of consciousness). Studies hâve shownthat a réduction in brain metabolism of some 47% is associated with a State of generalanaesthesia. Administration of excessive doses of anaesthetic compounds leads to aréduction in metabolic activity in excess of this level and a depth of anaesthesia that isexcessive and associated with an increased risk of side-effects. It is thereforeparticularly important for a clinician to be able to reliably and sensitively regulatebrain activity to allow the induction of controlled anaesthesia. A state of anaesthesia is physiologically different to sleep. For instance, asubject who is asleep may be easily roused and therefore remains sensitive to extemalstimuli whereas a subject under a general anaesthetic may not be roused toconsciousness by external stimuli. Furthermore sleep is not necessarily associatedwith reduced brain activity (e.g. during Rapid Eye Movement sleep, brain activity isnormally high) whereas general anaesthetic is associated with reduced activity. Giventhe différences between anaesthesia and sleep it is not surprising that anaestheticcompounds do not necessarily act as hypnotics and vice versa.

Small, volatile molécules which induce anaesthesia (e.g. alcohols, halothane, ether etc) hâve been known for many years and are, or hâve been, commonly used to 11758 2 induce and maintain anaesthesia prior to, and during, elective surgery etc. Howevermany conventional anaesthetics hâve various disadvantages. These include: (1) narrow concentration range over which the agent is effective (too Iittleand the subject regains sensitivity to extemal stimuli whereas too muchresuits in coma or death); (2) slow recovery following anaesthesia; (3) common side effects such as respiratory dépréssion, cardiovascularinstability and vomiting; and (4) uncommon but life threatening side-effects such as malignanthyperpyrexia.

Therefore there is a need to provide compounds which may be used as, or withanaesthetics, which obviate or mitigate disadvantages associated with the prior art.

According to a first aspect of the présent invention, there is provided the useof a compound which modulâtes Delta-Sleep Inducing Peptide activity for themanufacture of a médicament for regulating anaesthesia. DSIP is a nonapeptide (which can exist in linear or cyclic form) with theamino acid sequence:

Trp-Ala-Gly-Gly-Asp-Ala-Ser-Gly-Glu DSIP was discovered in the 1970’s and has been proposed for sleep induction(for which it has had only limited success) and for treating drug addicts during drugwithdrawal. However it has not previously been associated with anaesthesia and wehâve found that compounds which modulate DSIP activity are able to regulateanaesthesia. DSIP may cause a réduction in brain metabolism which may be associated with a changed level of consciousness. However, the inventors hâve established that the réduction in brain metabolism seen with anaesthesia Ieads to a change in consciousness which is not typical of normal sleep. In fact, following DSIP treatment 11758 Λ

J there is a decrease in the amount of Rapid Eye Movement sleep and an increase indelta wave activity. The inventors hâve correlated these changes with theanaesthetised State and hâve therefore established that compounds which modulateDSIP activity may be used according to the first aspect of the invention. The inventorsfurther believe that DSIP may be important in the induction of hibernation and theréduction of brain metabolic activity during hibernation and similar States.

The inventors believe that DSIP is an endogenous “anaesthetic-like” substancewhich modulâtes neurotransmission and brain activity. This belief is founded uponobservations made whilst conducting studies using PET to assess metabolic activitychanges that occur in varions areas of the brain during anaesthesia with conventionalanaesthetic agents. The invention arose from the réalisation that the areas of the brainin which there were changes in metabolic activity in response to a conventionalanaesthetic agent were the same areas where DSIP has been shown to be located usingimmunohistology techniques.

Although we do not wish to be bound by any hypothesis, we believe thatcompounds which modulate DSIP activity are effective because they regulate bindingof ligands with a neuromodulatory binding site on neuroreceptors which hâve beenlinked to the régulation of anaesthesia (e.g. the site described by Mihic et al. (1997)Nature 389 p3 85-3 89 on GABAa receptors and glycine receptors). We believebinding of DSIP to these receptors modulâtes signalling from these receptors andthereby régulâtes the level of brain metabolism and the level of anaesthesia.

Our hypothesis that DSIP acts as an anaesthetic was confirmed by experimentswhich established that administration of DSIP induces anaesthesia and also prolongsanaesthesia induced by other anaesthetic agents. For instance, anaesthesia following a7mg/kg iv bolus of propofol was approximately 28% longer in animais pretreatedwith DSIP (lmg/kg IP, 15 mins prior to the propofol bolus) compared to animaistreated with propofol alone. Further experimental data illustrating the efficacy ofDSIP, and related compounds, is presented in the Example below. 4 11758

According ίο a first embodiment of the first aspect of the invention, we hâvefound that compounds which increase DSIP activity may be administered alone, orpreferably in combination with certain other anaesthetic agents, to induce or maintainanaesthesia. When used as part of a régime to induce anaesthesia, compounds which 5 increase DSIP activity may be administered at the time of induction or at an earliertime as part of a regimen of pre-medication.

Several classes of compound which are capable of increasing DSIP activitymay be used according to the invention. Such compounds include agonists or partialagonists of DSIP neuromodulatory binding sites, agents which enhance the release of

10 endogenous agonists of DSIP neuromodulatory binding sites, agents which enhancethe synthesis of endogenous agonists of DSIP neuromodulatory binding sites, agentswhich attenuate the breakdown (or removal/sequestration) of endogenous DSIPagonists, agents which increase DSIP expression or activity and agents which enhancethe mechanisms involved in signal transduction between the ligand bound DSIP 15 binding site and effector Systems.

Preferred compounds which increase DSIP activity are DSIP agonists andinclude DSIP per se and dérivatives and/or pharamaceutically acceptable salts thereof.

Preferred DSIP agonists which may be used according to the first embodimentof the first aspect of the invention include the phosphorylated nonapeptides disclosed 20 in British Patent No. 2 000 511. (which are incorporated herein by reference).

Biologically active fragments of DSIP, biologically active DSIP dérivativesand larger peptides comprising the nonapeptide (or biologically active fragments anddérivatives thereof) are also preferred compounds for use according to the firstembodiment of the first aspect of the invention. For example a preferred dérivative of 25 DSIP is Cyclo(-GLY-DSIP) which is described by Nekrasov et al. (Biochem. Mol.

Biol. Int. 1996:38 p739-745). This dérivative is more lipophilie than DSIP and crosses the blood brain barrier more readily. Cyclo (-GLY-DSIP) is particularly usefuî for rapid induction of anaesthesia. 5 11758

It will be appreciated that non-peptide compounds which mimic peptide DSIPagonist activity (which may be isolated from nature or rationally designed) may alsobe used.

Compounds which modulate DSIP activity may be used in a method ofinducing anaesthesia comprising administering to a patient to be anaesthetised aneffective amount of a compound which promûtes DSIP activity to induce at least partof the desired level of anaesthesia.

We believe that DSIP (and functional analogues thereof) induce or maintainanaesthesia according to the first embodiment of the first aspect of the invention forthe following reasons: (1) It is a neuromodulator, not necessarily a neurotransmitter, which webelieve influences a transmembrane binding site on the GABAa, glycine and possiblyother receptors in a manner consistent with a modulator working via the same site asthe éthanol site and/or the enflurane anaesthetic site. (2) It is an anticonvulsant. (3) It has analgésie properties. We believe DSIP acts as an analgésie becauseit promûtes the release of met-enkephalin. (4) Studies to investigate a possible action of DSIP in sleep promotion hâveshown that it does not induce normal sleep stages but promûtes delta wave activity onthe electroencephalograph as do many anaesthetics. During anaesthesia theelectroencephalograph shows a complex pattern which may include a delta wavecomponent but this pattern is distinct from that seen during natural sleep stages. (5) It may regulate excitation and inhibition within the brain. It may modulatethermorégulation, as do general anaesthetics.

The analgésie properties of the compounds (3 above) represents a particular advantage of compounds used according to the first embodiment of the first aspect of the invention. Under certain circumstances the analgésie activity of a compound may outlast the anaesthetic action. This is of particular benefit as it will promote pain relief 11758 6 during a recovery period following surgery etc. Furthermore it will be appreciated thatthe analegesia promoted by the compounds is not associated with respiratorydépréssion (a common side-effect of many known analgésies e.g. morphine).

The inventors hâve found that compounds which increase DSIP activity areparticularly useful for treating patients who require long term ventilation in theintensive care setting. A problem associated with such patients relates to the longterm maintenance of an adéquate State of anaesthesia such that the patient ismaintained pain free and can be ventilated. Extensive clinical expérience has shownthat increasing doses of anaesthetic agents are required. In general, gaseous agentsare not used because of a number of major drawbacks including pollution of the localenvironment. Continuons intravenous anaesthesia using propofol is often used.However, accumulation of éléments of the propofol formulation results in undesirableeffects. Another major problem is that tolérance to the anaesthetic effects of propofoldevelops, in some cases rapidly, such that ever larger doses are required to maintainthe patient. Finally, when the time cornes to wean patients off the anaesthetic in orderto wean the patient off the ventilator, the respiratory dépréssion caused byconventional general anaesthetics is a major problem. The use of compounds thatincrease DSIP activity in this clinical setting has particular advantages becauseincreased DSIP activity does not cause respiratory dépréssion. Furthermore tolérancehas not been observed to the effects of the naturally occurring hormone. In addition,DSIP has activities that will confer additional benefits over many conventionalanaesthetics as follows: 1) DSIP has been shown to hâve analgésie activity of its own, possibly through therelease of met enkephalin; (pain is frequently a prominent problem in the longterm ventilated patient); and 2) DSIP has been shown to hâve a bénéficiai effect on the adaptive responses tostress (the intensive care setting is extremely stressful).

We hâve found that compounds which increase DSIP activity are alsoparticularly useful as adjuncts to other anaesthetics. When given in conjunction withother anaesthetics, compounds that increase DSIP activity prolong the duration of 11758 7 anaesthesia. Equally, when a compound according to the first embodiment of the firstaspect of invention is used as an adjunct, a satisfactory depth of anaesthesia may beachieved at a reduced l'evel of the other anaesthetic (compared to use of otheranaesthetics alone). This has the advantage of reducing the risk of side effects and/orthe discomfort associated with recovery from the use of higher amounts of anaestheticcompounds. For instance, known anaesthetics can be associated with respiratorydépréssion whereby patients stop spontaneous breathing. DSIP is not associated withrespiratory dépréssion. Therefore, administration of DSIP with a reduced level ofknown anaesthetic results in an acceptable level of anaesthesia withont respiratorydépréssion.

The use of DSIP and other compounds according to the first embodiment ofthe first aspect of the invention has the advantage that there is less risk ofcardiovascular instability. Other advantages of using the compounds include: (i) the kinetics of DSIP in vivo is non-saturable (metabolism is by plasmaand other non-specific esterases); (ii) peptide compounds such as DSIP are not toxic and need not be used asa gas. Therefore there is less environmental pollution during manufacture, use anddisposai; and (iii) compounds which promote DSIP activity also allow for instantaneousreversai, or at least quicker reversai, of general anaesthesia thereby further improvingor eliminating anaesthetic recovery times and improving anaesthetic safety (e.g. theuse of DSIP as an anaesthetic cofactor in combination with propofol helps smooth outpropofol induced anaesthesia and allows fewer intraoperative side effects) DSIP is degraded by a number of non-specific peptidases includingAngiotensin Converting Enzyme (ACE). Therefore it is preferred for someapplications that compounds according to the first embodiment of the first aspect ofthe invention are formulated with (or co-administered with) ACE inhibitors in orderthat DSIP activity may be potentiated. This is preferred when DSIP needs to be usedfor relatively long periods of time (e.g. anaesthesia and analgesia during intensivecare).

S 11758

According to a second embodiment of the first aspect of the inventioncompounds may be used which decrease DSIP activity.

Compounds according to the second embodiment of the first aspect of theinvention may be used for increasing brain activity for inducing recovery fromanaesthesia.

Several classes of compound which are capable of decreasing DSIP activitymay be used according to the second embodiment of the first aspect of the invention.Such compounds include antagonists or partial agonists of DSIP neuromodulatorybinding sites, agents which inhibit the release of endogenous agonists of DSIPneuromodulatory binding sites, agents which inhibit the synthesis of endogenousagonists of DSIP neuromodulatory binding sites, agents which promote thebreakdown (or removal/sequestration) of endogenous DSIP agonists, agents whichdecrease DSIP expression or activity and agents which inhibit the mechanismsinvolved in signal transduction between the ligand bound DSIP binding site andeffector Systems.

Preferred compounds which decrease DSIP activity are DSIP anatagonists andinclude melatonin, dalargin and neokyotorphin. A preferred use of compounds which decrease DSIP activity is to promoterecovery from anaesthesia. Thus, immediately before an operation, compoundsaccording to the first embodiment of the first aspect of the invention may be used(alone or in conjunction with another anaesthetic) to anaesthetise a subject and then,once the procedure has been completed, compounds according to the secondembodiment of the first aspect of the invention may be used to expedite recovery fromanaesthesia.

Brain activity may be regulated with compounds which modulate DSIP activity according to either embodiment of the first aspect of the invention as a 11758 9 monotherapy or in combination with other agents. For instance, anaesthesia may beinduced with compounds according to the first embodiment of the first aspect of theinvention alone (a monotherapy) or in combination with other known anaestheticagents (e.g. combination therapy with a DSIP agonist as an anaesthetic cofactor for 5 propofol or with a gaseous agent to reduce MAC. MAC being the Minimum AlveolarConcentration of anaesthesia necessary to achieve loss of movement to a noxiousstimulus in 50% of subjects).

When the compounds are used in combination with other agents, a lower doseof that agent may be required. This wilî reduce the incidence and severity of side- 1® effects known to be caused by such agents. The dose requirements are typicallyreduced by 20 — 50% depending upon the spécifie combination used.

The compounds used according to the first aspect of the invention may take anumber of different forms depending, in particular on the manner in which thecomposition is to be used. Thus, for example, the composition may be in the form of 15 a powder, tablet, capsule, liquid, ointment, cream, gel, hydrogel, aérosol, spray,micelle, liposome or any other suitable form that may be administered to a person oranimal. It wilî be appreciated that the vehicle of the composition of the inventionshould be one which is well tolerated by the subject to whom it is given and enablesdelivery of the compounds to the target tissue. 2® Preferred formulations include stérile, isotonie solutions for injection and micronised powders with excipients for oral inhalation.

The compounds may be used in a number of ways. For instance, systemicadministration may be required in which case the compound may be contained withina composition which may for example be administered by injection into the blood 25 stream. Injections may be intravenous (bolus or infusion) or subeutaneous (bolus or infusion). The compounds may also so be administered by inhalation. Altematively the compound may be ingested orally in the form of a tablet, capsule or liquid. 10 11758

Compounds modulating DSIP activity may be administered centrally bymeans of intracérébral, intracerebroventricular, or intrathecal delivery.

It will be appreciated that the amount of a compound required is determinedby biological activity and bioavailability which in turn dépends on the mode ofadministration, the physicochemical properties of the compound employed andwhether the compound is being used as a monotherapy or in a combined therapy. Thefrequency and/or rate of administration will also be influenced by the abovementioned factors and particularly the half-life of the compound within the subjectbeing treated. It will be appreciated that an anaesthetist will need to monitor the depthof anaesthesia of a subject during anaesthesia and adjust the required dose of thecompound as required.

Known procedures, such as those conventionally employed by thepharmaceutical industry (e.g. in vivo expérimentation, clinical trials etc), may be usedto establish spécifie formulations of compositions and précisé therapeutic régimes.

Generally, à dose of between 0.01 pg/kg of body weight and 1.0 g/kg of bodyweight of a compound which modulâtes DSIP activity may be used for the régulationof brain activity depending upon which spécifie compound is used and the reason forregulating activity. For instance, a suitable dose of a DSIP agonist will be in the rangeof between 1.0 pg/kg and 1.0 mg/kg (preferably 20 - 400pg/kg). Purely by way ofexample a suitable dose of DSIP for use in combination with propofol (e.g. 7mg/kg I.V. bolus) for inducing anaesthesia is between O.Olmg and 100 mg/kg and preferablybetween 0.02 mg/kg and 10 mg/kg.

Administration may be required frequently or continuously depending uponthe requirements of an anaesthetist. By way of example between lpg/kg/hr andlg/kg/hr, and preferably between lOpg/kg/hr and lOOmg/kg/hr of DSIP may berequired to maintain anaesthesia. 11758 Π

According to a second aspect of the présent invention, there is provided amethod of regulating anaesthesia comprising administering to a subject in need oftreatment a compound which modulâtes Delta-Sleep Inducing Peptide activity.

The abovementioned compounds which modulate DSIP activity according tothe first aspect of the invention may be used according to the method of the secondaspect of the invention.

According to a third aspect of the présent invention there is provided a methodof evaluating the anaesthetic needs of a subject to be anaesthetised comprisingassaying a sample taken from the subject for the presence of Delta-Sleep InducingPeptide.

By “anaesthetic needs” we mean an assessment of the dose of an anaestheticrequired to induce or maintain a desired level of anaesthesia.

We hâve found that anaesthetic dose requirements are directly related toendogenous levels of DSIP. Thus a pre-operative assay of DSIP levels in a subject(e.g. a simple urine or blood test screening for DSIP) provides an anaesthetic dosageguide for predicting anaesthetic requirements. Higher than average endogenous levelsof Delta-Sleep Inducing Peptide assayed from the sample indicate the subject willhâve lower than average anaesthetic requirements. Lower than average endogenouslevels of Delta-Sleep Inducing Peptide assayed from the sample indicate the subjectwill hâve higher than average anaesthetic requirements.

It will be appreciated that the normal range for endogenous DSIP will dépendupon the assay employed and the population studied. Purely by way of example DSIPlevels may be assessed using the assay described by Seifritz et al. (Peptides 1995; 16(8); pl 475 - 1481). Using this assay the range of DSIP in blood is approximately 0.1- 11 ng/ml. Therefore subjects with DSIP levels greater than about 5.0 ng/ml arelikely to need less anaesthetic than normal whereas subjects with DSIP levels lessthan about 5.0 ng/ml are likely to require more anaesthetic than normal. 12 11758 A suitable assay for measuring DSIP levels in a sample is a quantitativeimmunoassay utilising àntibodies raised against DSIP. For instance, the enzymeimmunoassay described by Kato et al. (Neuroendocrinology 1984;3 9:p3 9-44) may beadapted for use as a pre-operative test to evaluate anaesthetic requirements. An 5 alternative assay which may be used according to the third aspect of the invention is aradioimmunoassay (e.g. as described by Seïfritz et al. Supra). It is preferred that theassay médiates a colourmetric change which may be interpreted by eye orspectrophotometrically.

The sample is most suitably a blood or urine sample. 10 Such a method may be used pre-operatively to evaluate the anaesthetic needs of elective surgical patients.

According to one embodiment of the third aspect of the invention, ananaesthetist, nurse or theatre technician may test a blood or urine sample from a subject ashort while (approximately 30 minutes or îess) before anaesthesia to evaluate the 15 anaesthetic needs of the subject. This test may be by means of inserting into the samplea dip-stick which undergoes a colour change (depending upon the DSIP levels in thesample). An anaesthetist can then interpret the measured levels and adapt the anaestheticrégime accordingly.

The invention will be further illustrated by the following non-limiting Example. 11758

EXAMPLE

Experiments were performed in rodents to evaluate the effect of DSIP onanaesthesia induced by prôpofol.

Methods 5 Nine female Sprague-Dawley rats weighing 230 to 287g had free access to water and rat Purina chow. Ail animais were maintained, cared for, and handled in accordancewith IACUC animal utilization policy. Animais were divided into two groups to test theinteractions between DSIP and the intravenous anaesthetic agent propofol (n=5) or theinhalational anaesthetic agent isoflurane (n=4). For the propofol test, rats were randomly 10 selected to receive either Deîta-sleep inducing peptide (Peninsula Labs, CA) 1 mg/kg i.p. in 3 ml of stérile water or just 3 ml of stérile water i.p. alone (placebo) 15 minutes priorto injection of propofol (Trademarks: Diprivan or Rapinoivet) 7 mg/kg i.v. into a tailvein over approximately 10 s. Following injection of propofol animais were tested forloss of righting reflex. On loss of righting reflex the animais were placed on their sides 15 in the center of a large plastic bowl with a fiat bottom. Sleep time was recorded as thetime taken to regain righting with ail 4 feet on the ground. The following week, thoseanimais that had received DSIP now received placebo pretreatment and those that hadreceived placebo now received DSIP pretreatment. Again sleep time was assessed foreach rat, after giving each rat the identical dose of propofol that it had been given the 20 previous week.

For the inhalational test, rats were placed on a rotating rod in the middle of ananaesthetizing chamber. The level of inhalational agent was slowly titrated upwards in0.05% incréments every 10-15 min until the rats could no longer walk forward on therotating rod. At week one. rats were randomly selected to receive either DSIP 0.1 mg/kg 25 i.p. 15 min prior to testing, or placebo. The following week rats were crossed over to theother treatment ann (i.e. placebo to DSIP and DSIP to placebo).

Data were analyzed with a paired two-tailed t-tests. 14 11758

Results

Intraperitoneal injection of lmg/kg DSIP did not cause any rat to looseconsciousness. Rats did. however, display a paucity of movement almost immediatelyafter i.p. injection of DSIP. The animais did appear to be under the influence of some 5 pharmacologie effect following DSIP pretreatment, perhaps best described by noting thatthe rats appeared to hâve a “vacant” look about them when left undisturbed. Theanimais would, however, move appropriately when approached, but then would quicklyrésumé a crouched position when left alone.

Sleep times following propofol iv injection (7mg/kg) for each animal are shown 10 in Table 1.

Table 1 animal Sleep time (Sec) DSIP lmg/kg Sleep time (Sec) placebo 1 406 242 2 527 446 3 748 577 4 637 581 5 737 689

Each animal slept longer when pretreated with DSIP. The mean sleep time forpropofol alone was 477 +/- 158 Sec. The mean sleep time for DSIP pretreatmentfollowed by propofol was 611 +/- 145. This différence was significant at the P<0.01level and represents a mean 28% increase in sleep time. 15 The dose of isoflurane anaesthesia (chamber IS0%) required to prevent each animal from being able to walk forward on a rotating rod is shown in Table 2. 15 ’175g

Table 2 animal Chamber iso % Chamber iso % placebo Ψ DSIP O.lmg/kg 1 0.24 0.30 2 0.12 0.20 3 0.26 0.31 4 0.18 0.21

The mean (+/- SD) concentration of isoflurane that prevented animais from beingable to walk on the rotarod following placebo alone was 0.26 +/- 0.06%. The DSIPpretreatment reduced tlris value 23% to 0.20 +/- 0.06%. This réduction was statisticallysignificant at the p = 0.01 level. 5 These data illustrate that DSIP was particularly effective when used as an adjunct to both propofol and isoflurane. Table 1 illustrâtes that DSIP prolongs the length ofanaesthesia whereas Table 2 illustrâtes that DSIP is able to lower the concentration ofanother anaesthetic which is required to induce anaesthesia.

Claims

U 1 ? 7 5 8 CLAIMS

1. The use of Delta-Sleep Inducing Peptide or biologicaily active fragments anddérivatives thereof for the manufacture of a médicament for regulating anaesthesia.
2. The use according to claim 1 for promoting or inducing anaesthesia.
3. The use according to claim l for promoting or inducing sédation. $ 4. The use according to any preceding claim wherein the compound is for use in conjunctioa with another anaesthetic agent.
5. The use according to any preceding claim wherein the compound is anonapeptide with the amino acid seqœnce: Trp-Ala-Gly-Gly-Asp-Ala-Ser-Gly-Glu 1® - or biologicaily active fragments and dérivatives thereof.
6. The use according to claim 5 wherein at least one amino acid or dérivativethereof is phosphorylated.
7. The use of a compound that decreases Delta-Sleep Inducing Peptide activityfor the manufacture of a médicament for promoting or inducing recovery from 15 anaesthesia.
8. The use according to daim 7 wherein the compound is melatonin, dalargin orneokyotorphin..
9. A method of evaluating the anaesthetic needs of a subject to be anaesthetisedcomprising assaying a sample taken from the subject for the presence of Delta-Sleep 20 Inducing Peptide.
10. The method according to claim 9, wherein the sample is a blood or urinesample. 17 117 5 8 !
11. The method according to claim 9 or 10, wherein higher than averageendogenous levels of Delta-Sleep Inducing Peptide assayed from the sample indicatethe subject will hâve lower than average anaesthetic requirements.
12. The method according to claim 9 ôr 10, wherein lower than average5 endogenous levels of Delta-Sleep Inducing Peptide assayed from the sample indicate the subject will hâve higher than average anaesthetic requirements.