Methylene Blue Versus Vasopressin Analogue for Treatment of Septic Shock in Preterm Neonate

Neonate with Gestational age at birth ≤ 36weeks Inclusion Criteria: * diagnosis of Septic shock according to clinical sepsis score of Tollner and Hematologic Scoring System of Rodwell * Refractory septic shock defined as hypotension although adequate fluid resuscitate and high dose vasopressor(NE \>0.5 mcg/kg/min) * consent form Exclusion Criteria: * known case of G6pd deficiency * Hx of drug allergy MB, NE, terlipressin * Patients with severely impaired renal function. * History of maternal drug intake of selective serotonin reuptake inhibitors,and Serotonin-Norepinephrine Reuptake Inhibitors