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Equivalent dose of ephedrine and phenylephrine in the prevention of post-spinal hypotension in Caesarean section.
Br J Anaesth 2006; 96(1):95-9BJ

Abstract

BACKGROUND

Comparative studies of ephedrine and phenylephrine in prevention of hypotension after spinal anaesthesia for Caesarean section have lacked a consensus on dose equivalence. The aim of this study was to determine the minimum vasopressor dose for each of these drugs to calculate the dose ratio for clinical equivalence in the prevention of hypotension.

METHODS

Patients with a normal singleton pregnancy beyond 36 weeks gestation undergoing elective Caesarean section under spinal anaesthesia were randomized into two groups. The first patient in Group A received 50 mg of ephedrine in saline 0.9% w/v, 500 ml, at 999 ml h(-1), the maximum rate possible on the pump and the first patient in Group B received 500 microg of phenylephrine in saline 0.9% w/v, 500 ml, at the same rate. The initial dose for dilution was an arbitrary choice. The dose of vasopressor in the saline bag for every subsequent patient was established by the efficacy of the dose in preventing hypotension in the previous patient according to the technique of up-down sequential allocation. Minimum vasopressor dose for each drug was determined according to the Dixon-Massey formula.

RESULTS

The minimum vasopressor dose in saline 500 ml was 532.9 microg (95% CI 506.0-559.8) for phenylephrine and 43.3 mg (95% CI 39.2-47.3) for ephedrine. The concentration needed for equivalence at an infusion rate of 999 ml h(-1) was 1.07 microg ml(-1) for phenylephrine and 86.66 microg ml(-1) for ephedrine. Mean (sd) dose used for phenylephrine was 496.45 (78.3) microg and for ephedrine 39.64 (6.33) mg.

CONCLUSION

This study demonstrates a potency ratio of 81.2 (95% CI 73.0-89.7) for equivalence between phenylephrine and ephedrine in prevention of hypotension after spinal anaesthesia for Caesarean section.

Authors+Show Affiliations

Department of Anaesthesia, Hull Royal Infirmary, Anlaby Road, Hull, UK.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Comparative Study
Journal Article
Randomized Controlled Trial

Language

eng

PubMed ID

16311286

Citation

Saravanan, S, et al. "Equivalent Dose of Ephedrine and Phenylephrine in the Prevention of Post-spinal Hypotension in Caesarean Section." British Journal of Anaesthesia, vol. 96, no. 1, 2006, pp. 95-9.
Saravanan S, Kocarev M, Wilson RC, et al. Equivalent dose of ephedrine and phenylephrine in the prevention of post-spinal hypotension in Caesarean section. Br J Anaesth. 2006;96(1):95-9.
Saravanan, S., Kocarev, M., Wilson, R. C., Watkins, E., Columb, M. O., & Lyons, G. (2006). Equivalent dose of ephedrine and phenylephrine in the prevention of post-spinal hypotension in Caesarean section. British Journal of Anaesthesia, 96(1), pp. 95-9.
Saravanan S, et al. Equivalent Dose of Ephedrine and Phenylephrine in the Prevention of Post-spinal Hypotension in Caesarean Section. Br J Anaesth. 2006;96(1):95-9. PubMed PMID: 16311286.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Equivalent dose of ephedrine and phenylephrine in the prevention of post-spinal hypotension in Caesarean section. AU - Saravanan,S, AU - Kocarev,M, AU - Wilson,R C, AU - Watkins,E, AU - Columb,M O, AU - Lyons,G, Y1 - 2005/11/25/ PY - 2005/11/29/pubmed PY - 2006/1/31/medline PY - 2005/11/29/entrez SP - 95 EP - 9 JF - British journal of anaesthesia JO - Br J Anaesth VL - 96 IS - 1 N2 - BACKGROUND: Comparative studies of ephedrine and phenylephrine in prevention of hypotension after spinal anaesthesia for Caesarean section have lacked a consensus on dose equivalence. The aim of this study was to determine the minimum vasopressor dose for each of these drugs to calculate the dose ratio for clinical equivalence in the prevention of hypotension. METHODS: Patients with a normal singleton pregnancy beyond 36 weeks gestation undergoing elective Caesarean section under spinal anaesthesia were randomized into two groups. The first patient in Group A received 50 mg of ephedrine in saline 0.9% w/v, 500 ml, at 999 ml h(-1), the maximum rate possible on the pump and the first patient in Group B received 500 microg of phenylephrine in saline 0.9% w/v, 500 ml, at the same rate. The initial dose for dilution was an arbitrary choice. The dose of vasopressor in the saline bag for every subsequent patient was established by the efficacy of the dose in preventing hypotension in the previous patient according to the technique of up-down sequential allocation. Minimum vasopressor dose for each drug was determined according to the Dixon-Massey formula. RESULTS: The minimum vasopressor dose in saline 500 ml was 532.9 microg (95% CI 506.0-559.8) for phenylephrine and 43.3 mg (95% CI 39.2-47.3) for ephedrine. The concentration needed for equivalence at an infusion rate of 999 ml h(-1) was 1.07 microg ml(-1) for phenylephrine and 86.66 microg ml(-1) for ephedrine. Mean (sd) dose used for phenylephrine was 496.45 (78.3) microg and for ephedrine 39.64 (6.33) mg. CONCLUSION: This study demonstrates a potency ratio of 81.2 (95% CI 73.0-89.7) for equivalence between phenylephrine and ephedrine in prevention of hypotension after spinal anaesthesia for Caesarean section. SN - 0007-0912 UR - https://www.unboundmedicine.com/medline/citation/16311286/Equivalent_dose_of_ephedrine_and_phenylephrine_in_the_prevention_of_post_spinal_hypotension_in_Caesarean_section_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0007-0912(17)35270-4 DB - PRIME DP - Unbound Medicine ER -