Eye disorders
Janet M Rennie, Giles S Kendall in A Manual of Neonatal Intensive Care, 2013
The eye is said to show plus disease if there is dilatation and/or tortuousity of the retinal vessels. The eyes should be examined by an experienced ophthalmologist using indirect opthalmoscopy and after dilating the pupils with 0.5% cyclopentolate and 2.5% phenylephrine eye drops. The baby presents with irritability, photophobia and tearing from the eye which has an acute increase in intraocular pressure. All babies have a tendency to transient alternating convergent strabismus. This is of no significance and the eyes gradually straighten by 3–6 months of age. A baby is at risk from retinopathy of prematurity (ROP) until he passes the postmenstrual age of about 32–34 weeks. More severe forms of ROP are associated with abnormalities of the posterior retinal and iris blood vessels termed plus disease. Early gestation and low birth weight remain the strongest risk factors for the development of ROP.
Emergency drugs
Peter Nightingale in Anaesthetics for Junior Doctors and Allied Professionals, 2018
Emergencies happen frequently in anaesthesia. There are many categories of emergency drugs. These are metaraminol, ephedrine, atropine plus or minus glycopyrrolate and suxamethonium. Metaraminol is a very potent drug and must be diluted and used with care. Phenylephrine is a pure direct-acting a1 vasoconstrictor with similar properties to metaraminol. Ephedrine has direct α and β actions at adrenoceptors and an indirect action to increase noradrenaline release from nerve terminals. Noradrenaline is a far more potent drug and must be given centrally to avoid tissue necrosis. Indirect measurements of adequate flow such as capillary refill time, urine output, lactate level and, if appropriate, level of consciousness can be monitored during anaesthesia. Both atropine and glycopyrrolate are competitive antagonists at muscarinic receptors that act to block vagal parasympathetic stimulation. Atropine causes a profound vagal block and is more useful for profound bradycardias.
Antihistamines, Decongestants, and Expectorants during Pregnancy
“Bert” Bertis Britt Little in Drugs and Pregnancy, 2022
Approximately 15 percent of women take cold-flu-allergy medications for upper respiratory infections and nasal congestion. The drug classes include decongestants, antihistamines, expectorants, and antitussives. Pseudoephedrine hydrochloride is the most commonly used agent for pregnant women who require a decongestant. Pseudoephedrine is also part of a combination therapy and combined with different antihistamines in “common cold” or “sinus” medications. Phenylpropanolamine and phenylephrine are decongestants in wide use, and are commonly combined with various antihistamines in flu and cold over-the-counter preparations. Phenylephrine may also be used for the treatment of acute hypotension. Naphazoline, oxymetazoline, and xylometazoline are sympathomimetic agents with decongestant in long-acting nasal sprays. Doxylamine was one of the main components of the popular antinausea drug, Bendectin. Several studies reported an association of Bendectin use in pregnancy and diaphragmatic hernias, congenital heart disease, and pyloric stenosis. Piperidine was discovered in 1850 and is a substrate in the manufacture of several classes of drugs, including antihistamines.
Retrospective comparison of ephedrine and phenylephrine for the treatment of spinal anesthesia induced hypotension in pre-eclamptic patients
Published in Current Medical Research and Opinion, 2016
Unyime S. Ituk, Mary Cooter, Ashraf S. Habib
Objective: To compare neonatal acid base status in parturients who underwent cesarean delivery and received either ephedrine or phenylephrine boluses for the treatment of spinal anesthesia induced hypotension. Research design and methods: After institutional review board approval, the perioperative database of the University of Iowa Hospitals and Clinics was used to identify all women diagnosed with pre-eclampsia and had cesarean delivery under spinal anesthesia for the period 1 January 2005 to 31 July 2014. Data retrieved included patient demographics, indication for cesarean delivery, severity of pre-eclampsia, dose of vasopressor, neonatal umbilical artery pH and Apgar scores. Main outcome measures: Primary outcome was umbilical artery pH. Results: Data for 146 patients was included in the analysis. Ephedrine was used in 57 patients (group E) and phenylephrine in 89 (group PE) patients. The median umbilical artery pH was 7.30 (IQR 7.20–7.30) and 7.30 (IQR 7.20–7.30) in the ephedrine and phenylephrine groups respectively (P = 0.41). Non-reassuring fetal heart trace was the only factor significantly associated with lower umbilical artery pH on multivariable regression analysis (β = −0.09, P = 0.002). Conclusions: We found no difference in neonatal umbilical artery pH between ephedrine and phenylephrine when used to treat spinal anesthesia induced hypotension during cesarean delivery in pre-eclamptic patients. Limitations of the study include its retrospective single center design and the fact that the choice of vasopressor was not randomized.
Effect of phenylephrine on aqueous humor flow
Published in Current Eye Research, 1982
David A. Lee, Richard F. Brubaker
The effect of topical 2.5% phenylephrine hydrochloride, an alpha adrenergie agonist, on the rate of aqueous humor flow was studied in the eyes of 22 normal human subjects. The drug and a placebo were administered by random assignment from coded containers with the fellow eye serving as the control. Intraocular pressure, anterior chamber volume, corneal thickness and the rate of clearance of topically applied fluorescein from the anterior chamber were measured. Four of the 22 subjects underwent a study of the effect of phenylephrine on the permeability to fluorescein of the blood-aqueous barrier. No statistically significant effect of the drug was found on the rate of aqueous humor flow, intraocular pressure, anterior chamber volume, corneal thickness or permeability of the blood-aqueous barrier.
Effect of Phenylephrine Hydrochloride on Betamethasone Side Effect in Relation to Viscosity of Ophthalmic Preparations II - Gel-State
Published in Drug Development and Industrial Pharmacy, 1989
M. A. Kassem, M. A. Attia, F. S. Habib, A. A. Mohamed
Combination preparations of betamethasone and phenylephrine hydrochloride were prepared in the form of ophthalmic gels based on polye thylene glycols, PEG, a carboxyvinyl polymer (carborner 934) or methylcellulose. The intraocular pressure, IOP, was followed after the application of the se gels to the rabbit eye. Three parameters have been utilized to assess the performance of combination preparations of the two drugs. These are the area under the curve, AUC, the maximum response, MR, and the duration of side effect (increased the IOP). It was found that the inclusion of phenyle phrine hydrochloride in the gel reduces, to marked extent, viz. 80-90%, the AUC compared to the corresponding gel devoid of phenylephrine hydrochloride, and that,∼60% reduction in the duration of betamethasone side effect with regard to the IOP. The most effective gel system appeared to be methylcellulose based gel.