A hydrophilic interaction liquid chromatography - Tandem mass spectrometry method for the determination of phenylephrine in dried blood spots from preterm infants.

A sensitive and accurate hydrophilic interaction liquid chromatography - tandem mass spectrometry method (HILIC-MS/MS) was developed and validated for the determination of phenylephrine concentration in Dried Blood Spot (DBS) samples from preterm infants, after ocular administration of an ophthalmic solution with phenylephrine. Sample preparation involved the extraction of the analyte from an 85 µL DBS sample with methanol - acetonitrile (50:50, v/v). Chromatographic separation was achieved on an ACQUITY UPLC BEH AMIDE column, under isocratic conditions within a 5 min run. Detection was achieved with a triple quadrupole MS applying electrospray ionization in positive mode. The method was fully validated and proved precise and accurate with in a linear range of 0.59-3.53 ng/ml in blood. The method was developed to provide insights on the level of exposure of infant population to phenylephrine after ocular administration.

Objective evaluation of the systemic effects of topical application of 1% atropine sulfate ophthalmic solution in healthy horses.

OBJECTIVE To determine the safety of topical administration of 1% atropine ophthalmic solution in healthy horses by objectively measuring gastrointestinal transit time. DESIGN Randomized, masked, controlled crossover study. ANIMALS 6 adult geldings. PROCEDURES Horses were randomly assigned (3/group) to first receive topical treatment of the left eye with 1% atropine or artificial tears solution; the right eye was left untreated. After 24 hours of treatment every 6 hours, 200 nontoxic beads were administered to each horse via nasogastric intubation and treatment frequency was decreased to every 12 hours for 4 more days. Pupillary light reflexes (PLRs), mydriasis, heart rate, fecal bead passage, abdominal girth measurements, auscultable gut sounds, fecal weight, and clinical signs of abdominal pain were monitored. Following a 4-week washout period, horses received the opposite treatment in the left eye and measurements were repeated. Serum atropine concentration (reflecting systemic absorption) was measured with an ELISA at various points after initial atropine administration. RESULTS No horse had subjective or objective evidence of colic or ileus at any monitoring point. Complete mydriasis of the left eye with absence of the PLR was identified in 5 horses within 6 hours and in all 6 horses within 12 hours after initial atropine administration. One horse had mydriasis with an absent PLR in the untreated eye by day 5 of atropine treatment. At no point was atropine detected in serum samples of any horse. CONCLUSIONS AND CLINICAL RELEVANCE Topical atropine application at clinically appropriate doses induced no evidence of ileus in healthy horses.

Systemic effects of ophthalmic cyclopentolate on body weight in neonatal mice.

BACKGROUND: Cyclopentolate is standardly used in ophthalmologic examinations of neonates to facilitate screening for retinopathy of prematurity. Reports of systemic effects have raised concerns of an increased risk of feeding intolerance after the examinations. OBJECTIVES: The goal of this study was to evaluate systemic concentrations of cyclopentolate after ophthalmic administration, as well as assess changes in weight as an indirect measure of alteration in feeding. METHODS: Neonatal mice were randomized into three groups to simulate a neonatal model for ophthalmic medication administration. The cyclopentolate group received a one-time administration of tetracaine, cyclopentolate, and phenylephrine ophthalmologic solutions in accordance with the protocol used at the children's hospital. The placebo group received the same ophthalmic drop administration, except for normal saline in place of cyclopentolate, and the control group received no ophthalmic drops and minimal handling. Daily weights and serum samples to measure systemic concentrations of cyclopentolate post-ophthalmic administration were assessed at baseline and for 7 days following drop administration. RESULTS: Analysis of serum levels demonstrated detectability of systemic cyclopentolate after ophthalmic administration as early as 30 min (86 ng/ml), 1 h (60 ng/ml), and 24 h (6.2 ng/ml). There were also differences in weight gained on following ophthalmic administration observed between the cyclopentolate group and placebo group, with the cyclopentolate group weighing significantly less on days 3 and 7 (p = 0.02). CONCLUSIONS: RESULTS indicate cyclopentolate is absorbed systemically and instillation of cyclopentolate decreases weight gain in neonatal mice compared to placebo. These preclinical findings provide rationale for further studies in neonatal patients.

Phenylephrine eye drops in pediatric patients undergoing ophthalmic surgery: incidence, presentation, and management of complications during general anesthesia.

BACKGROUND: Phenylephrine eye drops are widely used as mydriatic agent to reach the posterior segment of the eye. In literature, many reports suggest a systemic absorption of this agent as a source of severe adverse drug reactions. Hence, we reviewed our experience with topical phenylephrine in ophthalmic surgery. METHODS: In May 2006, following US guidelines publication, a standard operating procedure was issued in our operating rooms to standardize the use of phenylephrine eye drops in our practice. Two years later, after the occurrence of a cluster of serious adverse drug reactions in infants undergoing surgery, a review of phenylephrine safety and systemic complications incidence was performed. RESULTS: We observed 451 pediatric patients, and 187 met the inclusions criteria: Among them, 4 experienced hemodynamic complications due to phenylephrine eye drops. The incidence of major complications was 2.1%. CONCLUSIONS: Two different patterns of side effects occurred. The first one was a cardiovascular derangement with severe hypertension and heart rate alterations; the other one involved exclusively pulmonary circuit causing early edema. These clinical manifestations, their duration, and treatment responses are all explainable by alfa1-adrenergic action of phenylephrine. This hypothetic pathogenesis has been confirmed also by the usefulness of direct vasodilators (anesthetic agents) and by the negative outcome occurred in the past with the use of beta-blockers.

Effects of MDMA alone and after pretreatment with reboxetine, duloxetine, clonidine, carvedilol, and doxazosin on pupillary light reflex.

RATIONALE: Pupillometry can be used to characterize autonomic drug effects. OBJECTIVE: This study was conducted to determine the autonomic effects of 3,4-methylenedioxymethamphetamine (MDMA, ecstasy), administered alone and after pretreatment with reboxetine, duloxetine, clonidine, carvedilol, and doxazosin, on pupillary function. METHODS: Infrared pupillometry was performed in five placebo-controlled randomized studies. Each study included 16 healthy subjects (eight men, eight women) who received placebo-MDMA (125 mg), placebo-placebo, pretreatment-placebo, or pretreatment-MDMA using a crossover design. RESULTS: MDMA produced mydriasis, prolonged the latency, reduced the response to light, and shortened the recovery time. The impaired reflex response was associated with subjective, cardiostimulant, and hyperthermic drug effects and returned to normal within 6 h after MDMA administration when plasma MDMA levels were still high. Mydriasis was associated with changes in plasma MDMA concentration over time and longer-lasting. Both reboxetine and duloxetine interacted with the effects of MDMA on pupillary function. Clonidine did not significantly reduce the mydriatic effects of MDMA, although it produced miosis when administered alone. Carvedilol and doxazosin did not alter the effects of MDMA on pupillary function. CONCLUSIONS: The MDMA-induced prolongation of the latency to and reduction of light-induced miosis indicate indirect central parasympathetic inhibition, and the faster recovery time reflects an increased sympathomimetic action. Both norepinephrine and serotonin mediate the effects of MDMA on pupillary function. Although mydriasis is lasting and mirrors the plasma concentration-time curve of MDMA, the impairment in the reaction to light is associated with the subjective and other autonomic effects of MDMA and exhibits acute tolerance.

Determination of atropine in biological fluids by micellar electrokinetic capillary chromatography in the presence of strychnine and tetracaine.

The identification and quantitation of atropine, in whole blood and gastric contents in the presence of strychnine and tetracaine is described. This method uses liquid-liquid extraction and micellar electrokinetic chromatography (MECC). Separations are made using a 50 cm long capillary and a borate/phosphate buffer at pH 9.2 with 50 mM sodium dodecyl sulfate (SDS). Linearity was established for the three compounds between 1.0 and 100 microg/mL, using scopolamine as internal standard. The limit of detection for atropine was estimated at 0.06 microg/mL and the limit of quantitation at 0.2 microg/mL. The run time is less than 30 min. Alternate parameters are proposed to reduce the run time to under 10 min. The method was applied to a forensic post-mortem case.

The systemic absorption of adrenaline from posterior segment infusion during vitreoretinal surgery.

BACKGROUND/PURPOSE: Adrenaline infused into the posterior segment of the eye during vitreoretinal surgery may be absorbed and give rise to unwanted cardiovascular effects. We sought to establish whether significant amounts of adrenaline are systematically absorbed. METHODS: This study was prospective and double-masked, with patients randomised into two groups. The first group received a posterior segment infusion containing Hartmann's solution alone (Hs group) and the second group received a posterior segment infusion of Hartmann's solution containing 0.5 ml of 1:1000 (0.5 mg) adrenaline per 500 ml (Hs + Ad group). Pre-medication and anaesthetic techniques were standardised for all patients. Venous blood samples were collected prior to induction, 5 min following intubation and 5, 10, 15 and 30 min following the commencement of the infusion. Samples were analysed for adrenaline levels using high-performance liquid chromatography. RESULTS: Ten patients were studied: 4 in the Hs group and 6 in the Hs + Ad group. The mean dose of adrenaline administered in the Hs + Ad group was 655.08 nmol (0.12 mg). The median serum adrenaline level following infusion for the Hs + Ad group was 0.15 nmol/l (LQ = 0.100, UQ = 0.360) and the median serum adrenaline level for the Hs group was 0.10 nmol/l (LQ = 0.100, UQ = 0.350). There was no overall statistical difference in the levels of serum adrenaline between the two groups, and furthermore adrenaline levels remained within physiological parameters for both groups. CONCLUSION: There does not appear to be significant adrenaline absorption from posterior segment infusion. Continued caution should be exercised, however, as idiosyncratic reactions may still occur.