The Median Effective Dose (ED50) of Paracetamol and Morphine : A Study of Interaction Study

Procare Riaya Hospital

Status: Completed

Conditions: Postoperative Pain

Treatments: Drug: Morphine; Drug: Paracetamol; Drug: Paracetamol- Morphine

Study type: Interventional

Funder types: Other

Identifiers

NCT01366313

PRH 02

Details and patient eligibility

About

The aim of our study is to define the median effective analgesic doses (ED50) of paracetamol, morphine, and their combination and determination the nature of their interaction administered IV for postoperative pain after moderate painful surgery using up-and-down and isobolographic methods.

Full description

Ninety patients scheduled to undergo moderately painful surgery were included in one of three groups. Determination of median effective (ED50) doses was performed by the Dixon and Mood up-and-down method. Initial doses were 1.5g and 5mg, with dose adjustment intervals of 0.5g and 1 mg, in the paracetamol and morphine groups, respectively. The initial doses of paracetamol and morphine were 1.5g and 3mg, respectively in the paracetamol-morphine combination group with dose adjustment intervals of 0.25g for paracetamol and 0.5mg for morphine. Analgesic efficacy was defined as a decrease to less than 3 on a 0-10 numeric pain scale, 45 min after the beginning of drug administration. Isobolographic analysis was used to define the nature of their interaction.

Enrollment: 90 patients

Sex: All

Ages: 18+ years old

Volunteers: No Healthy Volunteers

Inclusion criteria

1. ASA physical status І or ІІ
2. Moderately painful surgery patients
3. postoperative pain more than 3 on a numerical pain score (NPS) -

Exclusion criteria

1. contraindication to the use of paracetamol and morphine
2. Pregnancy
3. age younger than 18 yr
4. patient weight less 65kg
5. intra-operative regional anesthesia,
6. intra-operative administration of analgesics other than fentanyl,
7. postoperative pain less than 3 on a numerical pain score (NPS)

Trial design

Primary purpose: Treatment

Allocation: Randomized

Interventional model: Parallel Assignment

Masking: Double Blind

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90 participants in 3 patient groups

Paracetamol

Experimental group

Description:

initial doses was 1.5g g, with dose adjustment intervals of 0.5g . with maximum dose 2.5 g as an only starting dose / 24 h

Treatment:

Drug: Paracetamol

Morphine

Experimental group

Description:

Initial doses of morphine was 5mg, with dose adjustment intervals of 1 mg .

Treatment:

Drug: Morphine

Paracetamol-morphine

Experimental group

Description:

The initial doses of paracetamol and morphine were 1.5g and 3mg, respectively in the paracetamol-morphine combination group with dose adjustment intervals of 0.25g for paracetamol and 0.5mg for morphine.

Treatment:

Drug: Paracetamol- Morphine