Effects of topical antiglaucoma eye drops on prostaglandin E(2)-induced aqueous flare elevation in pigmented rabbits.
(73/873)
PURPOSE: To evaluate the role of topical instillation of some antiglaucoma agents on experimental elevation of aqueous flare induced by prostaglandin E(2) (PGE(2)) in pigmented rabbits. METHODS: Transcorneal diffusion of PGE(2) (25 microg/mL or 7.09 x 10(-2) mM) with the use of a glass cylinder was achieved to produce aqueous flare elevation in pigmented rabbits. An antiglaucoma agent was topically administered before application of PGE(2). Aqueous flare was measured with a laser flare cell meter. RESULTS: A single instillation of apraclonidine 1.15%, two instillations of epinephrine 1.25%, two instillations of dipivefrin 0.1%, and two instillations and one instillation of dipivefrin 0.04% eye drops inhibited 98%, 96%, 87%, 73%, and 47% of PGE(2)-induced aqueous flare elevation, respectively. Timolol 0.5%, nipradilol 0.25%, dorzolamide 1%, and pilocarpine 2% eye drops had no effects on the increase of PGE(2)-induced flare. CONCLUSIONS: Apraclonidine, epinephrine, and dipivefrin eye drops inhibit PGE(2)-induced elevation of aqueous flare in pigmented rabbits. (+info)
An in vitro study of ceftazidime and vancomycin concentrations in various fluid media: implications for use in treating endophthalmitis.
(74/873)
PURPOSE: To investigate the precipitation process of a mixture of vancomycin and ceftazidime by equilibrium dialysis and determine its subsequent effect on the level of free antibiotics for treatment of endophthalmitis. METHODS: Concentrations of vancomycin and ceftazidime in an equilibrium dialysis chamber were measured during the equilibrium process by high-performance liquid chromatography. Normal saline (NS), balanced salt solution (BSS), and vitreous were used separately as the medium of dialysis. RESULTS: Precipitation of ceftazidime occurred at 37 degrees C but not at room temperature and did not affect the pH of the medium. It formed precipitate on its own or when mixed with vancomycin in all the three media of NS, BSS, and vitreous. More precipitation was formed if ceftazidime was initially prepared in BSS than in NS. After 168 hours in the dialysis chambers, ceftazidime prepared in NS precipitated to 54% of that in vitreous, compared with 88% if prepared in BSS. At 48 hours, ceftazidime prepared in NS decreased from an initial concentration of 137.5 to 73.4 microg/mL in vitreous medium and to 6.3 microg/mL if prepared in BSS. Precipitation of vancomycin was negligible. CONCLUSIONS: Based on this in vitro investigation, ceftazidime precipitates in vitreous at body temperature, regardless of the presence of vancomycin. NS is preferred to BSS as a preparation medium for antibiotics for intravitreal injection, because the extent of ceftazidime precipitation is less. However, due to precipitation, the concentration of free ceftazidime in vitreous may not be sufficiently high for antibacterial activity against most common organisms. (+info)
Delayed hypersensitivity to brimonidine tartrate 0.2% associated with high intraocular pressure.
(75/873)
PURPOSE: To report the late presentation of an allergic reaction to brimonidine tartrate 0.2% associated with an elevation of intraocular pressure. METHODS: During a 6-month period six Caucasian patients (three were male), with primary open angle glaucoma (POAG) or ocular hypertension, with an allergic reaction to brimonidine tartrate eye drops were identified. Brimonidine was initiated as additional medical therapy in four patients and monotherapy in two patients. The median age of the patients was 67 years (range 57-73 years). RESULTS: There were nine eyes with a follicular conjunctivitis; three patients received brimonidine in one eye only. In two patients an additional redness of the periocular skin was present. The median duration on brimonidine therapy before the onset of the allergic reaction was 12 months (range 5-15 months). The median intraocular pressure (IOP) before the onset of the allergy was 18 mmHg (range 16-21 mmHg). There was a significant elevation of IOP at the time of the allergy with a median IOP of 28 mmHg (range 20-44 mmHg) (P = 0.007, Wilcoxon sign rank test). The cessation of brimonidine allowed the resolution of the allergic reaction. The intraocular pressure was then controlled with alternative medication in eight eyes. One patient went on to have filtering surgery. CONCLUSIONS: A delayed hypersensitivity reaction to brimonidine tartrate eye drops resembles a viral follicular conjunctivitis. It is imperative that it is recognised as such, as it may occur many months after brimonidine is initiated. This allergy has been found to be associated with a loss of control of the IOP. Though this is a small cohort of patients, it is not unreasonable to suggest that patients on brimonidine eye drops should be instructed to report promptly to their ophthalmologist the onset of redness of their eyes so that their glaucoma control may be reassessed. (+info)
Intraoperative pulmonary oedema in a child following systemic absorption of phenylephrine eyedrops.
(76/873)
Ophthalmic surgeons often apply phenylephrine topically to effect pupillary dilatation. We describe a paediatric patient in whom cardiac arrhythmias, severe hypertension and pulmonary oedema occurred following intraoperative ocular phenylephrine administration. We believe that systemic absorption of the drug was responsible and discuss ways in which this might be reduced when ocular phenylephrine is used in this context. (+info)
Effect of benzalkonium chloride on the stability of the precorneal tear film in rabbit and man.
(77/873)
Benzalkonium chloride, a surface-active preservative commonly used in eyedrop preparations, has been shown to hasten the drying of the precorneal tear film. In the rabbit, 0.01 per cent benzalkonium (the concentration usually employed as a preservative) shortened the time required for the appearance of dry spots on the corneal surface by a factor of about four. In man, an approximately twofold hastening was demonstrated. This effect is thought to preclude the use of this substance as a preservative in eyedrop preparations for use as local anaesthetics. (+info)
High-speed videotopographic measurement of tear film build-up time.
(78/873)
PURPOSE: To detect tear film regularity changes in the 15 seconds after a blink, by using a new high-speed videotopographic method. METHODS: The new system, based on a standard corneal topograph, allows registration of four photokeratoscopic images per second. Altogether, 15 eyes of 15 healthy volunteers and 7 eyes of 7 patients with dry eye were examined in this prospective preliminary study. The main outcome measures were changes in surface regularity index (SRI), surface asymmetry index (SAI), and corneal power. RESULTS: The corneal surface became more regular in the first few seconds after a blink. In healthy eyes, the trend line of SRI and SAI decreased (improved) significantly (P < 0.001) after a blink, in 10 of 15 eyes for the SRI and in 13 of 15 for the SAI. In the typical cases, the trend line for SRI reached its minimum level, on average, at 7.1 +/- 3.9 seconds after a blink and that for the SAI at 5.4 +/- 2.7 seconds. Similar trends were found in the dry-eye group. The changes in keratometric measures were small (mean range, <1.5% of the absolute value) and showed no definite trends. CONCLUSIONS: High-speed videotopography provides the possibility of quantitative measurement of tear-film dynamics and may have clinical value in the management of ocular surface disorders. After a blink, it takes the tear film approximately 3 to 10 seconds (tear film build-up time) to reach the most regular state. However, despite surface-regularity changes, the measured corneal powers are stable. (+info)
Pharmacological, pharmacokinetic and clinical properties of olopatadine hydrochloride, a new antiallergic drug.
(79/873)
Olopatadine hydrochloride (olopatadine, 11-[(Z)-3-(dimethylamino)propylidene]-6,11-dihydrodibenz[b,e]oxepin-2-acetic acid monohydrochloride) is a novel antiallergic/histamine H1-receptor antagonistic drug that was synthesized and evaluated in our laboratories. Oral administration of olopatadine at doses of 0.03 mg/kg or higher inhibited the symptoms of experimental allergic skin responses, rhinoconjunctivitis and bronchial asthma in sensitized guinea pigs and rats. Olopatadine is a selective histamine H1-receptor antagonist possessing inhibitory effects on the release of inflammatory lipid mediators such as leukotriene and thromboxane from human polymorphonuclear leukocytes and eosinophils. Olopatadine also inhibited the tachykininergic contraction in the guinea pig bronchi by prejunctional inhibition of peripheral sensory nerves. Olopatadine exerted no significant effects on action potential duration in isolated guinea pig ventricular myocytes, myocardium and human ether-a-go-go-related gene channel. Olopatadine was highly and rapidly absorbed in healthy human volunteers. The urinary excretion of olopatadine accounted for not less than 58% and the contribution of metabolism was considerably low in the clearance of olopatadine in humans. Olopatadine is one of the few renal clearance drugs in antiallergic drugs. Olopatadine was shown to be useful for the treatment of allergic rhinitis and chronic urticaria in double-blind clinical trials. Olopatadine was approved in Japan for the treatment of allergic rhinitis, chronic urticaria, eczema dermatitis, prurigo, pruritus cutaneous, psoriasis vulgaris and erythema exsudativum multiforme in December, 2000. Ophthalmic solution of olopatadine was also approved in the United States for the treatment of seasonal allergic conjunctivitis in December, 1996 (Appendix: also in the European Union, it was approved in February 2002). (+info)
Ocular tolerance of absorption enhancers in ophthalmic preparations.
(80/873)
The use of absorption promoters is a way to improve the bioavailability and therapeutic response of topically applied ophthalmic drugs. The ocular tolerance of 9 potential absorption promoters was investigated as well as the influence of the enhancers' concentration on the ocular tolerance. The substances tested were instillated repetitively (4 times per day, during 3 days, and once just before examination) as aqueous solutions onto rabbit corneas. Fluorescein dyeing enabled us to specifically mark corneal damage that was observed by confocal microscopy. The degree of corneal injury was assessed with an image-processing system that calculated the total fluorescent areas. Confocal microscopy results showed the relatively good tolerance of permeation enhancers like dimethyl sulfoxide (DMSO), decamethonium, edetate, glycocholate, and cholate in contrast to the poorly tolerated saponin and fusidate. Increasing the promoters' concentration led generally to an increase in corneal lesions. (+info)