Drug – bio-affecting and body treating compositions – Designated organic active ingredient containing – Having -c- – wherein x is chalcogen – bonded directly to...
Patent
1996-04-12
1998-01-13
Jarvis, William R.A.
Drug, bio-affecting and body treating compositions
Designated organic active ingredient containing
Having -c-, wherein x is chalcogen, bonded directly to...
A61K 31445
Patent
active
057080119
DESCRIPTION:
BRIEF SUMMARY
This application is a 371 of PCT/GB94/02249, filed Oct. 13, 1994, published as WO95/10277 Apr. 20, 1995.
FIELD OF THE INVENTION
This invention relates to a new therapeutic use for a known analgesic agent, i.e. bupivacaine or 1-butyl-N-(2,6-dimethylphenyl)-2-piperidinecarboxamide.
BACKGROUND OF THE INVENTION
Racemic bupivacaine is an effective long-acting local anaesthetic, and may be given as an epidural. However, racemic bupivacaine is cardiotoxic, having depressant electrophysiological and mechanical effects on the heart. It should therefore be used with caution in cardiac-compromised patients.
It is known that levobupivacaine is probably less cardiotoxic than dexbupivacaine and racemic bupivacaine. See, for example, Vanhoutte et al, Br. J. Pharmacol. 103:1275-1281 (1991), and Denson et al, Regional Anaesthesia, 17:311-316 (1992). Vanhoutte et al studied the effects of bupivacaine enantiomers on the electrophysiological properties of guinea pig isolated papillary muscle; this is based on their statement that "the cardiotoxicity of bupivacaine seems to be mainly of electrophysiological origin".
Many patients who require analgesics are undergoing concomitant therapy with other drugs, e.g. anti-hypertensive agents. Many such drugs are cardio-depressant. In particular, it has recently been reported that cardio-depressant effects are observed in isolated organs, following administrations of bupivacaine and Ca.sup.2+ channel inhibitors such as verapamil.
SUMMARY OF THE INVENTION
Surprisingly, it has been found that the effect of levobupivacaine on the heart is reduced, in respect not simply of electrophysiological properties, but also mechanical properties. Although racemic bupivacaine may have both electrophysiological and mechanical depressant effects on the heart, there is no evidence to suggest that these effects are linked.
In particular, it has now been found that levobupivacaine in man has less effect on stroke, cardiac and acceleration indices than racemic bupivacaine. As these are indices of myocardial contractility, this finding indicates that levobupivacaine is less cardio-depressant than racemic bupivacaine. This finding supports the use of levobupivacaine as a safer long-acting local anaesthetic for use in patients having or disposed to depressed myocardial contractility, i.e. a class of cardiac-comprised patients and also patients undergoing concomitant therapy with medicines having a cardio-depressant effect or with cytotoxic drugs. For the same reasons, levobupivacaine may also have beneficial therapeutic effects after certain kinds of surgery when sympathetic blockade is required with minimal cardio-depressant effects.
The agent may be the single isomer, but is effectively free of dexbupivacaine, e.g. in at least 80%, more preferably at least 90%, and most preferably at least 99%, enantiomeric excess. Any conventional salt, e.g. the hydrochloride, may be used.
DESCRIPTION OF THE INVENTION
For the purposes of the present invention, "depressed myocardial contractility" indicates that the patient is suffering from, or disposed to, heart failure at level 2, 3 or 4 of the New York Heart Association Scale. There are various therapeutic indications associated with reduced force of contraction of the heart, where the use of bupivacaine or its isomers, on the basis of prior knowledge, would have been contra-indicated. In certain populations, reduced mechanical effectiveness of the heart is a major problem.
Specific indications to which the present invention relates, and for which the use of levobupivacaine as an analgesic is thus appropriate, include hypertension, renal disease, viral illness, alcohol-dependence or effects, major ischaemia and diabetes. The invention is also applicable for providing anaesthesia in the old and frail, for stable post-infarct, shock, following cardiac surgery or multiple organ failure, and others at risk from post-myocardial infarcts.
The concentration of levobupivacaine to be given for effective utility, is for example, 0.25%, 0.5% or 0.75%, depending on the
REFERENCES:
Valenzuela, C. et al. (1994) "Stereoselective Bupivacaine Block of the Human Cardiac Delayed Rectifier Kv1.5 Channel" Biophys. J. 66:A205, abstract No. Tu-Pos383.
Butterworth, J.F. et al. (1993) "Bupivacaine Inhibits Cyclic-3', 5'-Adenosine Monophosphate Production" Anesthesiology 79:88-95.
Clarkson, C.W., L.M. Hondeghem (1985) "Mechanism for Bupivacaine Depression of Cardiac Conduction: Fast Block of Sodium Channels during the Action Potential with Slow Recovery from Block during Diastole" Anesthesiology 62:396-405.
Courtney, K.R., J.J. Kendig (1988) "Bupivacaine is an effective potassium channel blocker in heart" Biochimica et Biophysica Acta 939:163-166.
Burm, A.G.L. et al. (1994) "Pharmacokinetics of the enantiomers of bupivacaine following intravenous administration of the racemate" Br. J. Clin. Pharmac. 38:125-129.
Vanhoutte et al, British Journal of Pharmacology, vol. 103, pp. 1275-1281 May 1991.
Rutten et al, British Journal of Anaesthesia, vol. 67, pp. 247-256 Sep. 1991.
Bardsley Hazel Judith
Gristwood Robert William
Chiroscience Limited
Jarvis William R.A.
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