PHARMACOKINETICS AND ANALGESIC EFFICACY OF LAEVOBUPIVACAINE, FENTANYL AND CLONIDINE FOR POSTOPERATIVE PARAVERTEBRAL ANAESTHESIA.

INTERVENTION: Trade Name: Chirocaine Product Name: Chirocaine Product Code: PA 38/71/1 Pharmaceutical Form: Solution for injection INN or Proposed INN: Levobupivacaine Concentration unit: mg/ml milligram(s)/millilitre Concentration type: equal Concentration number: 2.5‐ Trade Name: Chirocaine Product Name: Chirocaine Product Code: PA 38/71/2 Pharmaceutical Form: Solution for injection INN or Proposed INN: Levobupivacaine Concentration unit: mg/ml milligram(s)/millilitre Concentration type: equal Concentration number: 5.0‐ Trade Name: Sublimaze Injection (2 ml ampoule) Product Name: Sublimaze injection (2 ml ampoule) Product Code: PA 748/44/1 Pharmaceutical Form: Solution for injection INN or Proposed INN: Fentanyl Concentration unit: µg/ml microgram(s)/millilitre Concentration type: equal Concentration number: 50‐ Trade Name: Catapres Product Name: Catapres Product Code: PA 7/14/3 Pharmaceutical Form: Solution for injection INN or Proposed INN: Clonidine Concentration unit: µg/ml microgram(s)/millilitre Concentration type: equal Concentration number: 150‐ CONDITION: We are aiming to provide postoperative analgesia for breast surgery PRIMARY OUTCOME: Main Objective: The objectives of the proposed study are to evaluate the pharmacokinetics of laevobupivacaine, fentanyl and clonidine by measuring their plasma concentrations at defined time intervals after paravertebral analgesia, and to investigate if fentanyl and clonidine have local anaesthetic–sparing effects when given as adjunctive analgesics for paravertebral analgesia. ; Primary end point(s): The objectives of the proposed study are to evaluate the pharmacokinetics of levobupivacaine, fentanyl and clonidine by measuring their plasma concentrations at defined time intervals after paravertebral analgesia. Primary outcome measure (apart from the plasma levels of the drugs) will be also pain scores on movement, measured on a 100mm visual analogue scale (VAS), recorded at the time of blood sampling postoperatively, and also cumulative Patient Controlled Analgesia morphine consumption over 36 hr. ; Secondary outcomes will include blood pressure, heart rate, respiratory rate, nausea/vomiting, pruritus, sedation scores and patient satisfaction (also on a 100mm VAS). Secondary Objective: The secondary objectives is to provide high degree of postoperative analgesia as measured by the patient's pain anad satisfaction scores. We are aiming for a pain score less than 40 mm on the Visual Analogue Scale with minimal use of intravenous opioids as rescue analgesia and a satisfaction score more than 80 mm on the same scale. INCLUSION CRITERIA: Patients presenting for breast surgery for cancer, who are not day cases and do not have contraindications for paravertebral analgesia will be approached. Are the trial subjects under 18? no Number of subjects for this age range: F.1.2 Adults (18‐64 years) yes F.1.2.1 Number of subjects for this age range F.1.3 Elderly (>=65 years) yes F.1.3.1 Number of subjects for this age range