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Neo-Synephrine Injection (Phenylephrine Hydrochloride Injection) - Summary


Boxed Warning




NEO-SYNEPHRINE hydrochloride, brand of phenylephrine hydrochloride injection, is a vasoconstrictor and pressor drug chemically related to epinephrine and ephedrine.
NEO-SYNEPHRINE hydrochloride is a synthetic sympathomimetic agent in sterile form for parenteral injection.

Neo-Synephrine (Phenylephrine) is indicated for the following:

NEO-SYNEPHRINE is intended for the maintenance of an adequate level of blood pressure during spinal and inhalation anesthesia and for the treatment of vascular failure in shock, shock-like states and drug induced hypotension or hypersensitivity. It is also employed to overcome paroxysmal supraventricular tachycardia, to prolong spinal anesthesia and as a vasoconstrictor in regional analgesia.

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Published Studies Related to Neo-Synephrine Injection (Phenylephrine Injection)

Comparison of intravenous ephedrine with phenylephrine for the maintenance of arterial blood pressure during elective caesarean section under spinal anaesthesia. [2010.03]
Hypotension is a major concern of the anaesthetists whenever subarachnoid block is performed especially in obstetric patients. Vasopressors have been shown to be more effective at limiting spinal hypotension than other treatment of hypotension like preloading and left uterine displacement...

Wrapping of the legs versus phenylephrine for reducing hypotension in parturients having epidural anaesthesia for caesarean section: a prospective, randomized and double-blind study. [2009.10]
CONCLUSION: Wrapping of the legs is a nonpharmacological, prophylactic method with similar blood pressure control to repeated doses of phenylephrine during epidural anaesthesia for caesarean sections.

ED95 of phenylephrine to prevent spinal-induced hypotension and/or nausea at elective cesarean delivery. [2009.04]
BACKGROUND: The purpose of this trial was to determine the 95% effective dose (ED95) of phenylephrine by intermittent i.v. bolus, to prevent spinal-induced hypotension and/or nausea at elective cesarean delivery... CONCLUSION: The ED95 of phenylephrine, administered as intermittent boluses to prevent pre-delivery spinal-induced hypotension and/or nausea at elective cesarean delivery, is at least 122 microg (lower limit of the confidence interval). The safety of this dose warrants further studies.

Separate and additive mydriatic effects of lidocaine hydrochloride, phenylephrine, and cyclopentolate after intracameral injection. [2008.02]
PURPOSE: To assess the separate mydriatic effect of lidocaine hydrochloride (Xylocaine), cyclopentolate, and phenylephrine after intracameral injection and evaluate whether intracameral Xylocaine and phenylephrine without cyclopentolate provide sufficient pupil dilation for cataract surgery. SETTING: Department of Clinical Science/Ophthalmology, Umea University Hospital, Umea, Sweden... CONCLUSIONS: Xylocaine plus phenylephrine injected intracamerally gave adequate intraoperative pupil dilation in routine phacoemulsification surgery. Cyclopentolate administrated intracamerally had no immediate additive mydriatic effect to intracameral Xylocaine combined with phenylephrine.

The effect of the intravenous phenylephrine on the level of spinal anesthesia. [2011.11]
BACKGROUND: Spinal anesthesia causes hypotension and bradycardia due to sympathetic nerve block and it is difficult to predict the level of sensory block and the duration of blockade. Recent studies have reported that intravenous phenylephrine can reduce the rostral spread of spinal anesthesia in pregnant women. We think a phenylephrine infusion will be useful for maintaining the baseline blood pressure by reducing the rostral spread of spinal anesthesia during the elective surgery of non-obstetric patients... CONCLUSIONS: Intravenous phenylephrine can decrease the rostral spread of spinal anesthesia during urologic surgery.

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Clinical Trials Related to Neo-Synephrine Injection (Phenylephrine Injection)

Safety of Phenylephrine Hydrochloride, Acetaminophen, Dimethindene Maleate Compared to Phenylephrine Hydrochloride Alone in Healthy Volunteers [Not yet recruiting]
This study will evaluate the safety of phenylephrine hydrochloride 10 mg + acetaminophen 500 mg + dimethindene maleate 1 mg compared to phenylephrine hydrocloride 10 mg alone in healthy volunteers.

Phenylephrine for Spinal Induced Hypotension [Recruiting]
This study is designed to determine the ED90 for a single dose of phenylephrine for the treatment of spinal induced hypotension in parturients presenting for an elective CD. The ED90 is the effective dose at which 90% of subjects will have a "positive" response to phenylephrine. The primary outcome measure is the ED90 for bolus phenylephrine. Secondary outcomes include the need for additional vasopressors, glycopyrolate to treat bradycardia, and the presence of hypertension following administration of phenylephrine.

Preventing Tolerance to Oxymetazoline in Allergic Rhinitis [Not yet recruiting]
The investigators wish to evaluate the effects of decongestants like oxymetazoline and the lessening of this effect with time called 'tolerance'. The investigators will demonstrate a reversal of this tolerance with nasal steroids i. e. the investigators will show that nasal steroids protect against tolerance. This will tell us more on how the investigators can make this treatment effective and safe for patients suffering with allergic rhinitis.

Variable Rate Phenylephrine Infusion for Prevention of Spinal-induced Hypotension for Cesarean Delivery [Not yet recruiting]
Rapid administration of crystalloid immediately after induction of spinal anesthesia (coload) to be more effective in terms of managing hypotension as compared to administering crystalloid before spinal anesthesia (preload).

Phenylehrine infusion is a safe and effective way to reduce incidence and frequency of hypotension during SA for cesarean delivery. Hypotension was virtually eliminated by use of high-dose prophylactic phenylephrine infusion at a rate of 100 g/min and rapid crystalloid coload up to two liters (administration at the time of SA). However, incidence of reactive hypertension was frequent up to 47% with decrease in maternal heart rate (HR). This may raise concern in patients in whom increase of blood pressure may be detrimental, like chronic hypertension and in the presence of a compromised uteroplacental blood flow. A recent study found that infusing phenylephrine at a fixed rate of 75 and 100 ug/min is associated with more episodes of hypertension than placebo or the lower infusion rates of 25 and 50 ug/min respectively. However, there was no reduction in the number of physician interventions (phenylephrine boluses and stopping the infusion) needed to maintain maternal systolic blood pressure within 20% of baseline among all groups. Prophylactic fixed rate infusions may have limited application in clinical practice, and a variable rate (i. e. modifying the rate according to hemodynamics) has been advocated. The bolus administration of phenylephrine to treat hypotension is still commonly used, but requests multiple interventions from the anesthesiologists and is time consuming.

Eighty patients scheduled for cesarean delivery under spinal anesthesia will be assigned to one of two groups. Immediately after spinal injection, rapid crystalloid colaod of lactated Ringer of 15 mL/kg over a period of 10-15 min will be initiated. Patients in Group I will receive infusion of normal saline (placebo) and patients in group II variable infusion rate of phenylephrine started at 0. 75 ug/kg (close to the dose of 50 ug/min recommended for fixed infusion rate). The number of interventions needed to maintain maternal systolic blood pressure within 20% of baseline, hemodynamic performance, intraoperative nausea and vomiting, and umbilical cord blood gases will be compared between the two groups.

We will define a reliable and safe method to ensure maternal hemodynamic stability during spinal anesthesia for cesarean delivery with the least physician interference.

Phenylephrine in Spinal Anesthesia in Preeclamptic Patients [Recruiting]
Hypotension remains a common clinical problem after induction of spinal anesthesia for cesarean delivery. Maternal hypotension has been associated with considerable morbidity (maternal nausea and vomiting and fetal/neonatal acidemia). Traditionally, ephedrine has been the vasopressor of choice because of concerns about phenylephrine's potential adverse effect on uterine blood flow. This practice was based on animal studies which showed that ephedrine maintained cardiac output and uterine blood flow, while direct acting vasoconstrictors, e. g., phenylephrine, decreased uteroplacental perfusion. However, several recent studies have demonstrated that phenylephrine has similar efficacy to ephedrine for preventing and treating hypotension and may be associated with a lower incidence of fetal acidosis. All of these studies have been performed in healthy patients undergoing elective cesarean delivery.

Preeclampsia complicates 5-6% of all pregnancies and is a significant contributor to maternal and fetal morbidity and mortality. Many preeclamptic patients require cesarean delivery of the infant. These patients often have uteroplacental insufficiency. Given the potential for significant hypotension after spinal anesthesia and its effect on an already compromised fetus, prevention of (relative) hypotension in preeclamptic patients is important. Spinal anesthesia in preeclamptic patients has been shown to have no adverse neonatal outcomes as compared to epidural anesthesia when hypotension is treated adequately. Due to problems related to management of the difficult airway and coagulopathy, both of which are more common in preeclamptic women, spinal anesthesia may be the preferred regional anesthesia technique. Recent studies have demonstrated that preeclamptic patients may experience less hypotension after spinal anesthesia than their healthy counterparts. To our knowledge, phenylephrine for the treatment of spinal anesthesia-induced hypotension has not been studied in women with preeclampsia. The aim of our study is to compare intravenous infusion regimens of phenylephrine versus ephedrine for the treatment of spinal anesthesia induced hypotension in preeclamptic patients undergoing cesarean delivery. The primary outcome variable is umbilical artery pH.

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Page last updated: 2011-12-09

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