Penetration of betaxolol HCL ionic suspension 0.25% and betaxolol HCL solution 0.50% into the aqueous humor.

PURPOSE: To determine the intraocular penetration of topical drops of betaxolol HCl 0.25% suspension and betaxolol HCl 0.50% solution into the aqueous humor. METHODS: Fifteen patients were randomly assigned to receive topical betaxolol HCl 0.25% suspension (n=7) or topical betaxolol HCl 0.50% solution (n=8) the day before cataract surgery. Aqueous samples were collected 2 hours after the administration of the morning dose during cataract surgery. Drug concentrations were determined by high-performance liquid chromatography with fluorescence detection. RESULTS: The mean aqueous humor concentration of topical betaxolol HCl 0.25% suspension was 275.1+/-168.8 micro g/mL (range 570-70 micro g/mL) and the mean aqueous humor concentration of topical betaxolol HCl 0.50% solution was 195.4+/-102.4 micro g/mL (range 334-50 micro g/mL) (p=0.281). CONCLUSIONS: The mean aqueous humor concentration of betaxolol 0.25% suspension was higher than betaxolol 0.50% solution; however, the difference was not statistically significant. With twofold reduced concentration and similar anterior chamber penetration, betaxolol 0.25% suspension could be first choice for Beta 1 selective blocker therapy when considered for patients with glaucoma.

Comparison of subretinal fluid levels of two 0.3% ciprofloxacin-containing eye drops.

PURPOSE: Two ophthalmic solutions of 0.3% ciprofloxacin eye drops are available in Turkey: Ciloxan and Siprogut. A previous study by the same authors was the first to report vitreous penetration of ciprofloxacin-containing eye drops. The aim of the present study was to compare the levels of drug found in the subretinal fluid by the two products following local administration. METHODS: Forty-three patients undergoing conventional retinal detachment surgery received either Ciloxan (22 patients) or Siprogut (21 patients). Beginning 6 h before surgery, two drops of solution were instilled onto the operative eye every 30 min for the first 3 h and then hourly for the next 3 h. Subretinal fluid samples were collected 30 min after administration of the last dose and were assayed for ciprofloxacin levels using a method involving high-performance liquid chromatography with fluorometric detection. RESULTS: The minimum and maximum subretinal fluid concentrations measured were 0.11 microg/mL and 0.65 microg/mL, respectively, with Ciloxan, and 0.08 microg/mL and 0.62 microg/mL, respectively wth Siprogut. There was no statistical difference between the subretinal fluid ciprofloxacin levels of the two products. The subretinal fluid drug evels attained by both products were below the minimum inhibitory concentrations of common ocular pathogens. CONCLUSIONS: Ciloxan and Siprogut can penetrate subretinal fluid. The ocular bioavailability of ciprofloxacin after local administration is equivalent for both pharmaceutical products.

Penetration of topical and oral ofloxacin into the aqueous and vitreous humor of inflamed rabbit eyes.

PURPOSE: This study aimed to investigate the penetration of topical and oral ofloxacin into aqueous humor and vitreous humor in post-traumatic endophthalmitis model in rabbits. METHODS: A standardized intraocular infection after penetrating injury was made in the right eyes of 16 rabbits. Intraocular infection was induced by intravitreal injection of a suspension of Staphylococcus aureus. The intact left eyes were maintained as controls. The animals were divided randomly into two groups. (1) In the topical group, two drops of ofloxacin 0.3% eyedrops were instilled to both eyes every 30 min for 4 h. (2) In the topical-oral group, two doses of 25 mg/kg of ofloxacin at 12-h intervals were given orally, then the protocol of the first group was applied. Aqueous and vitreous humor samples were taken 30 min after the last drop. Ofloxacin concentrations were measured by using HPLC. RESULTS: Mean aqueous levels of ofloxacin in control eyes were: 3.25 +/- 2.55 microg/ml in topical group. 4.58 +/- 5.39 microg/ml in topical-oral group. Mean aqueous levels in inflamed eyes were: 5.21 +/- 4.55 microg/ml in topical group, 10.34 +/- 8.88 microg/ml in topical-oral group. Mean vitreous levels of ofloxacin in control eyes were: 0.17 +/- 0.07 microg/ml in topical group, 1.30 +/- 1.23 microg/ml in topical-oral group. Mean vitreous levels in inflamed eyes were: 0.35 +/- 0.22 microg/ml in topical group, 3.48 +/- 2.69 microg/ml in topical-oral group. There was no significant difference among the groups (P > 0.05), however. CONCLUSIONS: The result of this study suggests that oral supplementation of ofloxacin to topical instillation increased the ocular levels of ofloxacin in the post-traumatic endophthalmitis model. Mean drug concentrations in aqueous and vitreous humors were above the 90% minimum inhibitory concentrations (MIC90) for most of the common microorganisms causing endophthalmitis in all eyes, except in the vitreous humors of the intact eyes instilled topically.

The effects of prolonged acute use and inflammation on the ocular penetration of topical ciprofloxacin.

PURPOSE: To study the aqueous and vitreous penetration of ciprofloxacin after prolonged acute topical administration and to investigate the effects of inflammation on drug penetration. METHODS: A standardized model of intraocular infection after penetrating injury was made in the right eyes of eight rabbits. The intact left eyes were maintained as the control. Two drops of ciprofloxacin 0.3% eyedrops were instilled topically every 1 h for 7 h to all eyes of the rabbits. Aqueous and vitreous samples (100 microl) were obtained half an hour after the last drop. Instillation was continued for 7 h more and samples were obtained as before. Drug concentrations were measured using HPLC. RESULTS: The mean aqueous humor levels of ciprofloxacin were: in control eyes 1.31 +/- 0.78 microg/ml after 7 h and 1.85 +/- 1.69 microg/ml after 14 h of instillation: in inflamed eyes 2.18 +/- 1.02 microg/ml after 7 h and 2.91 +/- 2.12 microg/ml after 14 h. The mean vitreous humor levels were: in control eyes 0.65 +/- 0.44 microg/ml after 7 h and 0.72 +/- 0.8 microg/ml after 14 h of instillation; in inflamed eyes 0.67 +/- 0.77 microg/ml after 7 h and 1.01 +/- 0.43 microg/ml after 14 h. However, the differences among the groups were not significant (P > 0.05). CONCLUSIONS: Ciprofloxacin penetration into aqueous humor was higher in 14-h topical application than that for 7 h. Inflammation increased the penetration of topical ciprofloxacin into aqueous while administered for 7 h and into both aqueous and vitreous humor while administered for 14 h. c

Subretinal fluid levels of topical, oral, and combined administered ciprofloxacin in humans.

AIMS: To investigate the subretinal fluid (SRF) penetration of ciprofloxacin following topical, oral, and combined administration. METHODS: 34 patients undergoing conventional retinal reattachment surgery were randomly assigned to three groups. Twelve patients received topical ciprofloxacin, 11 patients received oral ciprofloxacin, and the other 11 patients received combined drug administration. SRF drug level was measured by using high performance liquid chromatography method. RESULTS: The highest drug concentrations of all tested modes were attained following combined administration and lowest following topical administration (p<0.001). The SRF drug concentration following oral administration was also significantly higher than that of topical administration (p<0.001). Concentrations after oral and combined administration did not differ significantly (p = 0.217). CONCLUSIONS: Topical ciprofloxacin can penetrate SRF. Ocular bioavailability of ciprofloxacin in SRF after oral and combined administration is equivalent.

Ofloxacin levels after intravitreal injection. Effects of trauma and inflammation.

PURPOSE: This study was carried out to get an insight into the ofloxacin elimination after intravitreal injection in rabbits. We also studied the effects of trauma and inflammation on the vitreous ofloxacin levels after intravitreal injection of ofloxacin. METHODS: A penetrating eye injury in the right eye was inflicted on 24 rabbits and another 12 animals were used as control. A standardized intraocular inflammation was induced by intravitreal injection of a suspension of Staphylococcus aureus in half of the traumatized eyes. Ofloxacin (200 microg/0.1 ml) was injected into the midvitreous cavity of both traumatized and control right eyes, and samples were obtained at 2, 8, 24 and 48 h after injection. Drug concentrations were measured using high-pressure liquid chromatography analysis. RESULTS: Vitreous levels of ofloxacin were above the MIC(90) at 2 and 8 h in all groups for most of the common microorganisms causing endophthalmitis and also at 24 h in traumatized-infected eyes. At the second hour, the mean vitreous concentrations of ofloxacin both in traumatized and traumatized-infected eyes were lower than that in the control eyes (p < 0.05). At 8 h, the mean vitreous concentrations of ofloxacin in the traumatized and in the traumatized-infected eyes were higher than that in the control eyes (p < 0.05). At 24 h, the mean ofloxacin concentration was higher in the traumatized-infected eyes than that in control (p < 0.01) and traumatized eyes (p < 0.05), and also higher in the traumatized eyes than that in the control eyes (p < 0.05). The mean ofloxacin concentrations in the traumatized and traumatized-infected eyes were significantly higher (p < 0.01) than those in the controls at 48 h. The elimination half-life of ofloxacin in the control eyes was 5.65 h and trauma and inflammation prolonged the half-life to 9.47 and 9. 72 h, respectively. CONCLUSION: Clearance of ofloxacin is fast and appears to be reduced by trauma and inflammation. Therapeutic drug levels in traumatized-infected eyes were maintained up to 24 h. This may be an important pharmacokinetic advantage in treating endophthalmitis unless the dose used has local toxicity and allows a longer dose interval when the dose is repeated.

Penetration of topical, oral, and combined administered ofloxacin into the subretinal fluid.

AIMS: To assess the subretinal fluid (SRF) levels of ofloxacin following topical, oral or combined administration. METHODS: 31 patients undergoing conventional retinal reattachment surgery were randomly assigned to three groups. Nine patients received topical ofloxacin, 11 patients received oral ofloxacin, and the other 11 patients received combined administration. Collected SRF samples were analysed for drug level by using high performance liquid chromatography. RESULTS: SRF drug levels after oral and combined administration were significantly higher than that after topical administration (p=0.0002 and p=0.0002, respectively) while there was no significant difference between oral and combined administration (p=0.0844). CONCLUSIONS: Ocular bioavailability of ofloxacin in SRF after oral and combined administration is equivalent. The addition of oral ofloxacin to topical therapy increased drug SRF penetration sixfold.

Penetration of ofloxacin and ciprofloxacin in aqueous humor after topical administration.

BACKGROUND AND OBJECTIVE: To compare the aqueous humor levels of 0.3% ofloxacin and 0.3% ciprofloxacin containing eyedrops in patients with healthy cornea. PATIENTS AND METHODS: Fifty patients with cataract were randomly assigned to have 0.3% ofloxacin containing eyedrop (25 patients) or 0.3% ciprofloxacin containing eyedrop (25 patients). Both drugs were repetitively instilled to each patient for 6 hours before the surgery. Aqueous samples were collected after penetrating the anterior chamber during cataract extraction and assayed by high-performance liquid chromatography method. RESULTS: The aqueous humor level of ofloxacin (1.43 +/- 0.26 microg/ml, mean +/- SEM) was significantly higher than that of ciprofloxacin (0.35 +/- 0.07 microg/ml) following the topical application (P < .0002). CONCLUSION: Aqueous humor penetration of topical ofloxacin is about 4 times higher than that of topical ciprofloxacin when the drugs are applied as described above.

CYP2C19 genotype does not represent a genetic predisposition in idiopathic systemic lupus erythematosus.

BACKGROUND: The aetiology of systemic lupus erythematosus (SLE) is still unknown. In several cases, however, chemicals or drugs were identified as aetiological agents and associations with certain phenotypes of drug metabolising enzymes have been reported. The purpose of this study was to discover if there is an association between CYP2C19 polymorphism and susceptibility to SLE. METHODS: Racemic mephenytoin (100 mg orally) was given to healthy volunteers (n = 161) and SLE patients (n = 37) and then S-mephenytoin and R-mephenytoin were determined in eight hour urine samples. A 10 ml blood sample was obtained from healthy volunteers (n = 80) and SLE patients (n = 69) for genotypic assay. Each blood sample was tested for the detection of CYP2C19*1 and CYP2C19*2 (formerly wt and m1 respectively) by oligonucleotide ligation assay. RESULTS: The ratio of S/R-mephenytoin ranged from < 0.1 to 1.293 in healthy subjects and from < 0.1 to 1.067 in SLE patients. PM phenotype was observed in 2 of 37 patients with idiopathic SLE (5.4%) and 6 of 161 healthy subjects (3.7%). There were no significant differences in the frequency of PM phenotypes between the groups (Fisher's exact test, p = 0.64) or in the frequency distribution profiles of ratios of S-mephenytoin to R-mephenytoin. No significant differences in distribution of overall genotypes and in allele frequencies were observed between the two groups. No significant relation was found between clinical features and the overall genotype. CONCLUSION: The results of this study indicate that CYP2C19 genotype does not represent a genetic predisposition in idiopathic SLE patients.

Penetration of topical and oral ciprofloxacin into the aqueous and vitreous humor in inflamed eyes.

PURPOSE: To assess the aqueous and vitreous penetration of ciprofloxacin after topical and combined topical and oral administration and investigate the effects of inflammation on drug penetration. METHODS: A standardized penetrating injury was made in the right eyes of 16 rabbits. Intraocular inflammation was induced by intravitreal injection of a suspension of Staphylococcus aureus in these eyes. The animals were divided into two groups according to treatment methodology: topical and topical-oral. The intact left eyes of the animals were maintained as controls. In the topical treatment group, two drops of ciprofloxacin 0.3% were instilled to both eyes every 30 minutes for 4 hours. In the topical-oral treatment group, animals were given two oral 40 mg/kg doses of ciprofloxacin at 12-hour intervals. After the last oral dose, the protocol of the topical group was applied to these eyes. Half an hour after the last drop, 100-microL samples were taken from aqueous and vitreous humor of all eyes. Drug concentrations were measured using high-pressure liquid chromatography. RESULTS: Mean aqueous levels of ciprofloxacin in control eyes were 2.31 microg/mL (range, 1.02-6.27 microg/mL) in the topical group and 5.88 microg/mL (1.52-17.81) in the topical-oral group. Mean aqueous levels in inflamed eyes were 7.36 microg/mL (2.34-17.15) in the topical group and 14.43 microg/mL (2.18-18.66) in the topical-oral group. Mean vitreous levels in control eyes were 0.77 microg/mL (0.09-1.93) in the topical group and 1.01 microg/mL (0.49-1.57) in the topical-oral group. Mean vitreous levels in inflamed eyes were 0.95 microg/mL (0.18-1.27) in the topical group and 1.98 microg/mL (0.51-3.34) in the topical-oral group. There was no significant difference among the groups (P > 0.05). Mean aqueous levels in all eyes and mean vitreous levels in the combined topical and oral group of inflamed eyes were above the 90% minimum inhibitory concentration for most of the common microorganisms causing endophthalmitis. CONCLUSION: There is an increase in both aqueous and vitreous humor concentrations with inflammation and with oral and topical administrations, as opposed to topical only, of ciprofloxacin. Using oral as well as topical treatment may be a beneficial method of antibiotic prophylaxis in ocular trauma once a patient has received intravenous or intravitreal therapy.

CYP2D6 polymorphism in systemic lupus erythematosus patients.

OBJECTIVES: To determine whether patients with idiopathic systemic lupus erythematosus (SLE) are associated with impaired CYP2D6 activity and to gain insight into whether there is an association between particular CYP2D6 genotypes and susceptibility to SLE, and whether CYP2D6 polymorphism is linked to any specific clinical features of SLE. METHODS: Debrisoquine sulfate (10 mg p.o.) was given to 159 healthy volunteers and 39 idiopathic SLE patients. Genotypic assay was carried out in 80 healthy volunteers and 32 patients. A 10-ml blood sample was drawn for genotypic assay. Debrisoquine and 4-hydroxydebrisoquine were determined in 8-h urine samples. Blood samples were analysed for the presence of mutations in the CYP2D6 gene, by using polymerase chain reaction (PCR) specific for CYP2D6*3 and CYP2D6*4 alleles. RESULTS: The metabolic ratio of debrisoquine to 4-hydroxydebrisoquine ranged from 0.01 to 86.98 in healthy subjects and from 0.02 to 96 in SLE patients. We observed the poor metabolizer(PM) debrisoquine phenotype in three of 39 patients with idiopathic SLE (7.6%) and five of 159 healthy subjects (3.1%). There was no significant difference in the frequency of PM phenotypes between idiopathic SLE and healthy subjects (Fisher's exact test, P = 0.19). No significant difference in the distribution of overall genotypes and allele frequencies were observed between the two groups. No significant relationships were found between specific clinical features and the overall genotype. CONCLUSION: The results of this study confirm that CYP2D6 activity is not impaired in SLE and that there is no association between SLE and phenotypic CYP2D6 status. The results also showed that there was no difference in the frequency of CYP2D6A and CYP2D6B alleles between controls and patients with SLE.

Effects of trauma and infection on ciprofloxacin levels in the vitreous cavity.

OBJECTIVE: This study was designed to determine the effects of trauma and infection on vitreous ciprofloxacin levels after intravitreal injection of ciprofloxacin in rabbits. METHODS: A penetrating injury was made in the right eyes of 24 rabbits. In the eyes of half of the traumatized animals, a standardized intraocular infection was induced by intravitreal injection of a suspension of Staphylococcus aureus. The intact left eyes of the traumatized group were maintained as controls. Ciprofloxacin (200 microg/0.1 mL) was injected into the midvitreous cavity of both eyes in all animals and samples were obtained at 2, 8, 24, and 48 hours after injection. Drug concentrations were measured using high-pressure liquid chromatography analysis. RESULTS: At the second hour, the mean vitreous concentration of ciprofloxacin in the traumatized eyes was lower than that in control eyes (P<0.05). The mean ciprofloxacin concentrations were significantly higher (P<0.05) in the traumatized-infected eyes than were those in control or traumatized eyes at 24 and 48 hours. The elimination half-life of ciprofloxacin in control and traumatized eyes was 6.02 hours and 5.02 hours, respectively, and infection prolonged the half-life to 15.06 hours. Vitreous levels of ciprofloxacin were above the minimum inhibitory concentration (MIC90) for most of the common microorganisms causing endophthalmitis in all groups at 2 and 8 hours, but also at 24 and 48 hours in traumatized-infected eyes. CONCLUSION: Infection appears to decrease the clearance of ciprofloxacin. Therapeutic drug levels in traumatized-infected eyes were maintained up to 48 hours. Assuming that the animal model used may have a predictive value for the drug elimination in traumatized-infected human eyes, we suggest that local administration of ciprofloxacin every 2 days may be relevant from the therapeutic perspective.

Aqueous humour levels of topically applied ciprofloxacin and ofloxacin in the same subjects.

PURPOSE: To evaluate aqueous humour levels of topical 0.3% ciprofloxacin and 0.3% ofloxacin in the same subjects. METHODS: Thirty-two bilateral cataractous patients received topical 0.3% ciprofloxacin in one eye and 0.3% ofloxacin in the other eye before each cataract extraction. Eyedrops were repetitively instilled for 6 h. Aqueous humour samples were collected and assayed for drug concentrations by a method described originally by us using high-performance liquid chromatography. RESULTS: Mean aqueous ciprofloxacin and ofloxacin levels were 0.33 +/- 0.04 microgram/ml (mean +/- SEM) and 1.34 +/- 0.14 micrograms/ml respectively (p < 0.0001). CONCLUSION: Ofloxacin level in the aqueous humour is 4 times higher than that of ciprofloxacin in the same subjects.

Human aqueous and vitreous humour levels of ciprofloxacin following oral and topical administration.

PURPOSE: To assess aqueous and vitreous humour ciprofloxacin concentrations following oral and topical administration of ciprofloxacin in patients with non-inflamed cornea and an intact crystalline lens, and to compare the concentrations of the drug given by either route. METHODS: In this prospective study, 34 patients undergoing pars plana vitrectomy for various ocular pathologies were divided into two groups. Eighteen patients received 2 drops of 0.3% ophthalmic solution of ciprofloxacin every 30 min for 3 h and then every 60 min for the next 3 h, and 16 patients received a single oral dose of 1000 mg ciprofloxacin 6 h before surgery. The aqueous and vitreous humour samples were simultaneously harvested after oral or topical administration during pars plana vitrectomy to assess penetration of the drug. These samples were assayed for ciprofloxacin concentrations by a method described previously by us using high-performance liquid chromatography. RESULTS: The aqueous and vitreous humour levels of ciprofloxacin were 0.59 +/- 0.06 microgram/ml (mean +/- SEM) and 0.64 +/- 0.06 microgram/ml after oral and 0.44 +/- 0.07 microgram/ml and 0.22 +/- 0.04 microgram/ml after topical ciprofloxacin administration, respectively. Aqueous humour levels were not statistically significantly different following oral and topical administration (p = 0.069). However, the vitreous level of the drug after oral administration was significantly higher than that after topical administration (p < 0.001). CONCLUSION: Ocular bioavailability of ciprofloxacin in aqueous humour following oral and topical administration is found to be similar when the drug was applied as described above. Penetration of ciprofloxacin into vitreous humour is less than that into aqueous humour after topical administration.

Penetration of ofloxacin in human aqueous and vitreous humors following oral and topical administration.

PURPOSE: To determine aqueous and vitreous humor ofloxacin levels following oral and topical application of ofloxacin in patients with noninflamed cornea and intact crystalline lens, and to compare the drug levels provided by each route. MATERIALS AND METHODS: Twenty-six patients undergoing pars plana vitrectomy for various ocular pathologies were divided into two groups. Fourteen patients received two drops of 0.3% ophthalmic solution of ofloxacin every 30 minutes for 3 hours and every 60 minutes for the next 3 hours, and 12 patients received a single oral dose of 400 mg ofloxacin 8 hours before surgery. The aqueous and vitreous humor samples were simultaneously collected after oral or topical administration during pars plana vitrectomy to assess penetration of the drug. Samples were assayed for ofloxacin concentrations by a previously described method using high-performance liquid chromatography. RESULTS: The aqueous and vitreous humor levels of ofloxacin were 1.54 +/- 0.27 microg/mL (mean +/- standard error) and 1.77 +/- 0.24 microg/mL after oral and 1.44 +/- 0.24 microg/mL and 0.37 +/- 0.05 microg/mL after topical ofloxacin administration, respectively. Aqueous humor levels were not statistically different following oral or topical administration (P > 0.8). However, vitreous level of the drug after oral administration was significantly higher than that after topical administration (P < 0.001). CONCLUSION: Ocular bioavailability of ofloxacin in aqueous humor after oral and topical administration is similar when the drug is applied as described. Penetration of ofloxacin into vitreous humor is less than that into aqueous humor following topical application. The aqueous humor levels of ofloxacin via both routes and the vitreous level of the drug after oral route exceed the minimum inhibitory concentrations for certain bacterial species that frequently cause intraocular infection.

Omission of the deconjugation step in urine analysis and the unaltered outcome of CYP2D6 phenotyping with dextromethorphan.

The present study was aimed at determining whether the deconjugation step in chemical analysis could be omitted without altering the outcome of phenotyping CYP2D6 with dextromethorphan. This drug and its metabolite, dextrorphan, were assayed by high-performance liquid chromatography (HPLC) in urine. Urinary levels of dextromethorphan and dextrorphan with and without enzymatic (beta-glucuronidase) treatment of urine and the metabolic ratios for dextromethorphan were determined in 45 subjects. Although the enzymatic treatment did not alter the urinary concentration of dextromethorphan in both phenotypes, it increased the urinary concentration of dextrorphan in both poor and extensive metabolizers by 3.7- and 12.8-fold, respectively. A urinary unconjugated dextromethorphan/unconjugated dextrorphan metabolic ratio of 2.00 and a total dextromethorphan/total dextrorphan metabolic ratio of 0.30, respectively, identified three poor metabolizers. Enzymatic treatment decreased the urinary antimode value. Moreover, the urinary metabolic ratio based on unconjugated dextrorphan and dextromethorphan correlated well with that based on assay of total dextrorphan and dextromethorphan (rs = 0.9458, P < 0.001). The results show that urinary analysis of dextrorphan and dextromethorphan omitting the enzymatic deconjugation step is a fast, reliable and sensitive method and could be used for studying CYP2D6 type genetic polymorphism in man.

Optimization of mobile phase in the separation of beta-blockers by HPLC.

Beta-blockers are generally determined using high-performance liquid chromatography (HPLC). Previous HPLC separations of beta-blockers have often required a mobile phase containing three components; acetonitrile or methanol to control the retention; buffer to control the ionic strength and pH of the mobile phase; ion-pairing reagent to provide adequate retention of beta-blockers or organic amines as masking agent to reduce peak tailing. Due to the complexity of the mobile phases employed, development of these assays can be a laborious process. Additionally, alkyl sulphonates and organic amines dramatically reduces the life-time reduction of silica based C18 columns. The results of this study demonstrated that the addition of tested alkyl sulphonates and organic amines is not essential for an adequate separation of beta-blockers. In this study, we developed a simple HPLC method for the simultaneous separation of model beta-blockers, atenolol, practolol, metoprolol, oxprenolol and propranolol. Atenolol, practolol, metoprolol, oxprenolol and propranolol adequately separated with high peak symmetries using a mobile phase consisted of methanol/acetonitrile/phosphate buffer (10 mM, pH 3.0) (15:15:70, v/v/v). By altering only the fraction of methanol with respect to acetonitrile, method development becomes a more efficient separation. Furthermore, atenolol, practolol, metoprolol, oxprenolol and propranolol can be detected up to 0.25, 5, 10, 50 and 10 ng ml(-1). In this publication, we present the simultaneous separation of beta-blockers having a wide range of polarity. It is proposed that this new mobile phase, consisting only acetonitrile, methanol and phosphate buffer can be used for the analysis of the several beta-blockers presently in doping control analysis as well as others.

Comparison of aqueous humour and vitreous humour levels of two 0.3% ciprofloxacin eyedrops.

BACKGROUND: Two ophthalmic solutions of 0.3% ciprofloxacin eyedrops are available in Turkey: Ciloxan and Siprogut. The objective of this study was to compare the concentrations of drug produced by the two products in the aqueous humour and vitreous humour after local administration. METHODS: Twenty-one patients undergoing primary vitreoretinal surgery received either Ciloxan (10 patients) or Siprogut (11 patients). Six hours before surgery, two drops of solution were instilled onto the operative eye. Drops were then instilled every 30 minutes for the first 3 hours and then hourly for the next 3 hours. Aqueous and vitreous samples were collected 30 minutes after administration of the last dose and were assayed for ciprofloxacin concentration by means of high-performance liquid chromatography with fluorometric detection. RESULTS: The mean aqueous humour concentrations of Ciloxan and Siprogut were 0.36 (standard error of the mean [SEM] 0.09) microgram/mL and 0.44 (SEM 0.17) microgram/mL respectively. The corresponding vitreous humour concentrations were 0.21 (SEM 0.05) microgram/mL and 0.22 (SEM 0.06) microgram/mL. Neither of these differences was statistically significant. The aqueous and vitreous levels of both products exceeded the minimum inhibitory concentrations for certain bacterial species that frequently cause intraocular infections. INTERPRETATION: Our results show that the ocular bioavailability of Ciloxan and Siprogut after local administration is equivalent. Penetration of ciprofloxacin into the vitreous humour seems to be poorer than that into the aqueous humour.

Determination of ofloxacin in human aqueous humour by high-performance liquid chromatography with fluorescence detection.

A reversed-phase high-performance liquid chromatographic method is described for the determination of ofloxacin in human aqueous humour; the method involves fluorescence detection (excitation at 290 nm; emission at 500 nm) after direct injection of samples. The method utilized a 100 mm x 8 mm i.d. cartridge column packed with 4 microns Novapak C18 with a mobile phase methanol-acetonitrile-0.4 M citric acid (3:1:10, v/v/v) and a flow rate of 1 ml min-1 at ambient temperature. The retention times for the internal standard pipemidic acid and for ofloxacin were 4.82 and 7.32 min respectively. The mean recovery (+/- ISD) from human aqueous humour was 103.24 +/- 4.45% for ofloxacin at 1 microgram ml-1 (n = 6). The within-day and day-to-day RSDs at 0.1 microgram ml-1 and 1 microgram ml-1 were less than 6.71% (n = 6) and the lower limit of reliable determination corresponding to a signal-to-noise ratio of 2.5:1 was 20 ng ml-1. The assay was shown to be suitable for measuring ofloxacin levels in human aqueous humour samples after topical, oral and intravenous administration.