[Structural and functional characteristics of hemoglobin molecules from the preserved donor blood during long-term storage]

The human blood haemoglobin molecules keep their quaternary structure for 25 days at a long-term storage of the blood stabilised with glugicyr. The molecules' electronic characteristics did not change during 5 days, and their oxygen-binding ability remained unaltered just during 2 days after taking the blood.

In vitro evaluation of open heart surgery tubing coated with heparin and lipid

The aim of this work was to evaluate in vitro the tromboresistence, hemolysis tendency, platelet adhesion, cytotoxicity, physicochemical properties, and stability of open-heart tubing coated with fractionated heparin-benzalkonium chloride and/or lipid dipalmitoyl L-alpha-phosphatidylcholine (DPPC). The tendency for clot formation and platelet adhesion was greater in noncoated and lipid-coated tubing than in heparin-coated tubing. There were no significant differences between the hemolytic potentials of coated and noncoated tubing. The coatings were stable during the time of the experiment. The coatings did not present cytotoxicity and physicochemical alterations.

A new ELISA kit for measuring urinary 2-hydroxyestrone, 16alpha-hydroxyestrone, and their ratio: reproducibility, validity, and assay performance after freeze-thaw cycling and preservation by boric acid

There is considerable controversy regarding the role of estrogen metabolites in breast cancer risk, fueled in part by the development of a rapid ELISA that is suitable for large scale investigations. An earlier version of the ELISA could detect values of the 2-hydroxyestrone (2-OHE1) and 16alpha-hydroxyestrone (16alpha-OHE1) metabolites as low as 2 ng/ml and produce consistent results in premenopausal urines. However, reproducibility was problematic in postmenopausal urines where concentrations of these compounds are much lower. In response to our concern, a new ELISA was developed with a sensitivity of 0.625 ng/ml, which we evaluated using the same pre- and postmenopausal urine samples analyzed in the earlier ELISA. In this report, we present findings on the new kit with regard to reproducibility of the 2-OHE1 and 16alpha-OHE1 measurements, comparability of results with gas chromatography-mass spectroscopy values, and with regard to the stability of the metabolites after repeated freeze-thaw cycles and after preservation by boric acid. For the most part, we found the new ELISA to be reproducible, with assay coefficients of variation ranging from 10 to 20%, and intraclass correlation coefficients (ICCs) ranging from 80 to 95% in both the pre- and postmenopausal urines. ELISA results for 16alpha-OHE1 differed from 1 day (i.e., batch) to the next, and the absolute values of the metabolites obtained by the ELISA were consistently lower than but well correlated with those obtained by gas chromatography-mass spectroscopy. Values of the 2-OHE1:16alpha-OHE1 ratio also differed between the methods, but because the range of values was not large, the magnitude of these differences was not as great. For the ratio, the correlation between methods was excellent, and the ICCs were high for both groups of women. After preservation by boric acid, values of the ratio varied according to acid concentration but not in a linear fashion. Ratio values were similar in urine samples exposed to four different freeze-thaw cycle treatments, although values for all treatments were consistently lower in one batch. Because batch-to-batch variability was not negligible, it is advisable that matched cases and controls be analyzed in the same batch. Provided this is done, the relatively low assay coefficient of variation and high ICC demonstrate that the new ELISA kit can reliably measure the 2-OHE1:16alpha-OHE1 ratio and detect small case-control differences in large population-based studies, where rapid and relatively easy laboratory methods are critical.

Availability of hepatitis B vaccine that does not contain thimerosal as a preservative

On August 27, 1999, Merck Vaccine Division (Merck & Co., Inc., West Point, Pennsylvania) received approval from the Food and Drug Administration (FDA) of a supplement to Merck's license application to include the manufacture of single-antigen preservative-free hepatitis B vaccine (Recombivax HB, Pediatric); distribution is expected to begin September 13, 1999. In addition, SmithKline Beecham Biologicals (SmithKline Beecham, Philadelphia, Pennsylvania), expects to make single-antigen preservative-free hepatitis B vaccine (Engerix-B, Pediatric) available in the near future. Further product information will be provided when it becomes available. Product packaging and labels will indicate that these vaccines do not contain preservative.

Thimerosal in vaccines: a joint statement of the American Academy of Pediatrics and the Public Health Service

The Food and Drug Administration (FDA) Modernization Act of 1997 called for FDA to review and assess the risk of all mercury-containing food and drugs. In line with this review, U.S. vaccine manufacturers responded to a December 1998 and April 1999 FDA request to provide more detailed information about the thimerosal content of their preparations that include this compound as a preservative. Thimerosal has been used as an additive to biologics and vaccines since the 1930s because it is very effective in killing bacteria used in several vaccines and in preventing bacterial contamination, particularly in opened multidose containers. Some but not all of the vaccines recommended routinely for children in the United States contain thimerosal.

Incidence of contamination of preserved saline solutions during normal use

PURPOSE

To ascertain the incidence of microbial contamination of preserved contact lens saline solutions with normal patient use.

METHODS

Eight different brands of preserved saline were dispensed to 40 patients attending optometric practices in the Sydney area. After specific periods of time (7 to 28 days), the samples were collected and the solution bottle nozzles and contents underwent microbial analysis.

RESULTS

The overall contamination rate was approximately 26% for contents only and 55% for nozzles of preserved saline solutions. This rate remained constant for all periods of use. Coagulase-negative Staphylococci were most frequently isolated. No Acanthamoebae were isolated. Saline preserved with ethylene-diamine-tetraacetic acid (EDTA) in conjunction with sorbic acid showed the highest percentage of sterility.

CONCLUSIONS

The results of this study show that preserved saline became contaminated with gram-positive bacteria. This is in contrast to our previously published paper using unpreserved saline, where contamination was predominantly with gram-negative bacteria. The overall contamination rates with preserved saline were lower than for unpreserved saline.

Latest advances in nasal drug-delivery technology

Nasal delivery devices are not only limited to local medical therapy. The nasal route is an alternative to invasive or oral drug administration. The penetration of bioactive molecules through the nasal mucosa has been shown to achieve good bioavailability, and nasal sprays offer patients greater convenience. This article reviews some of the latest devices for liquid and dry-powder formulations, including preservative-free systems, and the business benefits they offer.

Comparison of preservative-free bupivacaine vs. lidocaine for intracameral anesthesia: a randomized clinical trial and in vitro analysis

PURPOSE

To determine whether intracameral bupivacaine hydrochloride 0.5% is as effective as lidocaine hydrochloride 1.0% in controlling discomfort of patients during phacoemulsification and posterior chamber intraocular lens implantation. In rabbits, corneal endothelial cell function, ultrastructure, and viability were evaluated after in vitro perfusion of bupivacaine 0.5%.

METHODS

In a double-masked, controlled trial, 48 eyes of 48 patients with uncomplicated age-related cataract were randomly assigned to receive bupivacaine 0.5% or lidocaine 1.0% intracamerally before phacoemulsification with a posterior chamber intraocular lens. Outcome measures such as pain, visual acuity, amount of sedation, length of surgery, pupil size, intraocular pressure, corneal clarity, and anterior chamber reaction were compared. In laboratory studies, paired rabbit corneas were evaluated by endothelial cell perfusion with either bupivacaine 0.5%, bupivacaine 0.5% and glutathione bicarbonate Ringer solution in a 1:1 ratio or bupivacaine 0.5% buffered to a pH of 7.0. The paired control corneas were perfused with glutathione bicarbonate Ringer solution and rates of corneal swelling were determined. Cell ultrastructure and viability were also evaluated.

RESULTS

In the randomized trial, there was no significant difference in the pain patients had during surgery or in the early or late postoperative period. No statistically significant difference was seen between the two groups in terms of pupil size, intraocular pressure, corneal edema, anterior chamber reaction, or visual acuity immediately after the operation or on postoperative day 1. Paired rabbit corneas perfused with bupivacaine 0.5% and bupivacaine 0.5% buffered to a pH of 7.0 swelled significantly (P<.001, P = .009, respectively), and had corneal endothelial cell damage. Dilution of the bupivacaine 1:1 with glutathione bicarbonate Ringer solution prevented corneal edema and damage to the corneal endothelium. Endothelial cell viability was also decreased after perfusion of bupivacaine 0.5% (P<.001).

CONCLUSIONS

Clinically, bupivacaine 0.5% is as effective as lidocaine 1.0% for anesthesia during phacoemulsification and posterior chamber intraocular lens implantation. However, in vitro perfusion of bupivacaine 0.5% damaged the corneal endothelium of rabbits except when the drug was diluted 1:1 with glutathione bicarbonate Ringer solution. Surgeons who use 0.2 to 0.5 ml of intracameral bupivacaine 0.5% should be aware of its potential to cause endothelial cell damage because of its lipid solubility. The bupivacaine 0.5% should be diluted at least 1:1 with balanced salt solution before intracameral injection, followed immediately by phacoemulsification. The surgeon should ensure that the bupivacaine 0.5% is nonpreserved and packaged in single-use vials or flip-top containers.

Topical nonpreserved methylprednisolone therapy for keratoconjunctivitis sicca in Sjögren syndrome

OBJECTIVE

To review the efficacy and side effects of topical nonpreserved corticosteroid therapy for treatment of severe keratoconjunctivitis associated with Sjögren syndrome.

DESIGN

Retrospective, noncomparative case series.

PARTICIPANTS

Twenty-one patients with Sjögren syndrome-associated keratoconjunctivitis sicca and annoying ocular irritation.

INTERVENTION

Treatment with topical nonpreserved methylprednisolone sodium succinate.

MAIN OUTCOME MEASURES

Symptom severity, frequency of instillation of artificial tears, corneal fluorescein staining scores, resolution of filamentary keratitis, steroid-related side effects.

RESULTS

Before starting methylprednisolone therapy, all patients were experiencing moderate-to-severe eye irritation despite prior punctal occlusion in most cases and frequent use of nonpreserved artificial tears by all. After 2 weeks of topical application, three to four times per day, moderate (43%) or complete (57%) relief of irritation symptoms was experienced by all patients and no complications were observed. An average decrease in corneal fluorescein scores of 2.6 +/- 0.5 points (on a 12-point scale) was observed, and filamentary keratitis resolved in all ten eyes with this condition. Therapy was stopped after 2 weeks in eight patients, and six of these patients reported that their symptoms remained at a tolerable level for weeks to months. Lower dose steroid therapy was continued in the remaining patients, whose symptoms worsened after attempted weaning. Complications of corticosteroid therapy in patients receiving prolonged therapy included increased intraocular pressure in one patient at 3 months, worsening of pre-existing posterior subcapsular cataracts in one patient at 6 months, and formation of posterior subcapsular cataracts in another patient at 6 months.

CONCLUSIONS

These findings indicate that topical nonpreserved methylprednisolone is an effective treatment option for patients suffering from severe keratoconjunctivitis sicca who continue to experience bothersome eye irritation despite maximum aqueous enhancement therapies. They also suggest that inflammation is a key pathogenic factor in this condition. Careful monitoring is essential in dry eye patients treated with corticosteroids for more than 2 weeks because steroid-related complications (increased intraocular pressure and cataract formation) were observed after several months of therapy in this series. Because of the chronic nature of this disease and the likelihood of patients developing steroid-related complications with their long-term use, topical nonpreserved methylprednisolone therapy appears to be most appropriate for short-term "pulse" treatment of exacerbations of keratoconjunctivitis sicca.

Comparison of the efficacy and safety of two eye gels in the treatment of dry eyes: Lacrinorm and Viscotears

PURPOSE

To compare the efficacy and safety of two carbomer 940 eye gels in the treatment of dry eyes: Lacrinorm (also called GelTears), a recently introduced eye gel, and Viscotears (also called Vidisic or Lacrigel), used as a reference gel. The main difference between the two gels is in the preservative, respectively benzalkonium chloride and cetrimide.

METHODS

A double-masked, randomised, parallel-group study was conducted in 16 centres in four European countries. A total of 179 patients suffering from aqueous-deficient dry eye were enrolled, of whom 92 were randomised to treatment with Lacrinorm and 87 to the reference gel. Gel was instilled four times a day for a period of 30 days.

RESULTS

After 30 days of treatment, subjective symptoms (the combined scores of foreign body sensation, ocular dryness, burning or pain, and photophobia) had improved by 50% in the Lacrinorm group and by 45% in the reference gel group, and objective test results (break-up time, fluorescein test, Schirmer test, Lissamine Green test) by 35-36% in the Lacrinorm group and 25-45% in the reference group. The improvements were significant in both treatment groups (p < 0.001), with no significant differences between the treatment groups. Subjective local tolerability upon instillation on day 30 was rated 'good' or 'very good' by 91% of patients in both treatment groups. Adverse events were reported for 21 patients in the Lacrinorm group and 17 in the reference group, the most frequent being discomfort, blurred vision, hyperaemia, burning and itching. The frequency and descriptions of adverse events did not differ significantly between the two treatment groups. No serious adverse events were reported.

CONCLUSIONS

Over the period of study, Lacrinorm eye gel was as effective and safe as Viscotears/Lacrigel in the treatment of dry eye.

Efficacy and safety of nonpreserved ketorolac ophthalmic solution in postoperative ocular pain following radial keratotomy

PURPOSE

To investigate the efficacy and safety of nonpreserved ketorolac tromethamine 0.5% ophthalmic solution in relieving pain following radial keratotomy (RK).

SETTING

Multicenter clinical trial.

METHODS

Topical ketorolac was compared with its vehicle in a double-masked, randomized, parallel-group study involving 170 RK patients. Patients were treated with nonpreserved ketorolac 0.5% ophthalmic solution or the vehicle 4 times daily beginning immediately after surgery and continuing for 3 days or until they no longer had ocular pain.

RESULTS

At several intervals, patients treated with ketorolac reported significantly greater pain relief and less pain intensity than patients treated with the vehicle. The time required for patients to first report "complete relief" or "no pain" was shorter in the ketorolac than in the vehicle group (P < or = .006). Patients in the ketorolac group used less escape medication (acetaminophen) (P < or = .001) and had fewer sleep difficulties (P < or = .031), fewer symptoms of ocular discomfort (P < or = .028), and less difficulty performing activities of daily living (P = .048). Patients treated with ketorolac experienced the same low rate of treatment-related adverse events as those treated with the vehicle and exhibited the same improvement in visual acuity and manifest refraction.

CONCLUSIONS

Nonpreserved ketorolac tromethamine 0.5% ophthalmic solution was significantly more effective than, and as safe as, the vehicle in alleviating the postoperative pain associated with RK. This resulted in significant improvements in patient quality of life and less need for oral analgesics, suggesting that topical ketorolac is an appropriate treatment option for ocular pain following RK.

A comparison of patient comfort during cataract surgery with topical anesthesia versus topical anesthesia and intracameral lidocaine

OBJECTIVE

To determine whether intraocular lidocaine increases patient comfort during cataract surgery while under topical anesthesia.

DESIGN

Prospective, randomized, double-masked, placebo-controlled clinical trial.

PARTICIPANTS

Both men and women between 45 and 85 years of age who were scheduled for elective cataract surgery while under topical anesthesia participated. Sixty-eight patients were randomized to each group.

INTERVENTION

Patients were randomized to receive either topical anesthesia plus intracameral 1% preservative-free lidocaine or intracameral balanced salt solution.

MAIN OUTCOME MEASURES

Patient assessment of pain during delivery of the anesthesia, surgery, and after surgery using a visual analog pain scale was measured. Patients also recorded the degree to which they were bothered by tissue manipulation and the microscope light. Surgeon assessments of operative conditions, patient cooperation, and intraoperative complications were recorded. The attending anesthesiologist recorded any required supplemental intravenous sedation and any increase in pulse or increase in blood pressure.

RESULTS

There was no significant difference in patient-reported pain scores for delivery of anesthesia (P = 0.902), surgery (P = 0.170), or after surgery (P = 0.680). Patients in the lidocaine group reported being less bothered by tissue manipulation (P = 0.021). The surgeon assessment showed more patient cooperation in the lidocaine group (P = 0.043).

CONCLUSIONS

Both topical anesthesia alone and topical anesthesia plus intracameral lidocaine provide good operative conditions for the surgeon and comfortable surgical circumstances for the patient. Injection of intraocular lidocaine increases patient cooperation and decreases the degree to which patients are bothered by tissue manipulation, two outcomes that justify its use.

Acoustic measurements in a tissue mimicking liquid

A liquid has been developed that mimics soft tissue in terms of propagation speed, attenuation, and nonlinearity parameter B/A. Since the slope of the attenuation coefficient is nearly constant up to at least 18 MHz and the value can be anywhere in the range 0.1 through 0.7 dB/(cm MHz), the material is ideal for assessing the effectiveness of attenuation derating of output acoustic intensities and pressures measured in water. A clinical ultrasound system was used to transmit into the tissue mimicking liquid. The pulse intensity integral and rarefactional pressure at various field locations in the tissue mimicking liquid were computed and compared to the corresponding values measured in water with attenuation derating applied. The slope of the attenuation coefficient in the tissue mimicking liquid was used for the derating. From this data it is seen that the present practice of modeling in vivo exposure using linearly derated measurements made in water is not always conservative.

The utility of patch tests using larger screening series of allergens

BACKGROUND

The number of patch test allergens available within the United States for routine commercial purchase is limited. Allergens chosen for inclusion in routine screening series or patch test trays vary, and the degree of information obtained from any series may or may not serve a patient's needs.

OBJECTIVE

Knowledge of how well the allergens chosen for inclusion in the two commercially available sources perform compared with a more expansive panel of tests can help physicians select the more appropriate tests.

METHODS

From 1994 to mid-1997, 554 patients were tested with allergens recommended by the North American Contact Dermatitis Group (NACDG). This included all allergens currently available from both current domestic sources, although not in the identical form used by the Thin-layer Rapid Use Epicutaneous Test (TRUE) test (Glaxo Dermatology, Research Triangle Park, NC). Another 185 patients were tested with supplemental series of allergens.

RESULTS

The larger the series of allergens used, the more positive tests were found and the more relevant tests as well. Hermal patch test allergens identified about 55% of the information found by the NACDG series; the TRUE test allergens (but not in the TRUE test system) identified 65%. Of the 103 reactions to supplemental allergens not found by the NACDG series, 59 were relevant.

CONCLUSION

Larger series of allergens can enhance accurate diagnosis of allergic contact dermatitis. No single arbitrary series of allergens can adequately survey the contemporary environment of individual patients. Selection of allergens for testing requires consideration of the patient's history and access to appropriate environmental contactants.

Safety and efficacy of intracameral injections of unpreserved lidocaine to reduce intraocular sensation

PURPOSE

To determine the safety and efficacy of intracameral injections of unpreserved lidocaine to reduce intraocular sensation.

SETTING

Carolina Eye Associates, Southern Pines, North Carolina, USA.

METHODS

In this prospective study, 100 patients having phacoemulsification under topical anesthesia were randomly assigned to receive an intracameral injection of unpreserved lidocaine (0.5 cc of a 1% unpreserved solution) or balanced salt solution.

RESULTS

Ninety-three patients completed the study. There were no significant between-group differences in cell density parameters or Kowa laser flare-cell meter measurements. Seventy-eight percent of lidocaine patients and 56% of controls reported no sensation (P = .048, Fisher's exact test).

CONCLUSION

Intracameral injections of unpreserved lidocaine safely and effectively reduced intraocular sensation during phacoemulsification.

Liquid or solid ultrasonically tissue-mimicking materials with very low scatter

A new tissue-mimicking material for ultrasound, using evaporated milk as the primary absorption component, is described. It has very low backscatter but still exhibits the 1540 m s-1 propagation speed and proportionality of attenuation coefficient and frequency over the diagnostic frequency range. The material can be produced in solid or liquid form with attenuation coefficient slopes spanning the range 0.1-0.7 dB cm-1 MHz-1. The liquid form is useful in phantoms where detailed beam patterns are to be determined, either involving translation of measurement devices in the liquid or phantoms with fibers present for causing the only detectable echoes. In the latter case, the liquid quality allows removal of liquid with one attenuation coefficient slope and replacement with another. The solid form may be more useful than the liquid for two reasons. First, many simulated lesions (including ones that produce essentially no internal echoes) can lie in the scan slice with positions extending over the entire image area without enhancement or shadowing effects being of concern. Second, the lack of significant backscatter from the material in the absence of added scatterers allows the backscatter coefficient to be varied over a considerable range. A critical result is that intrinsic material contrast between targets and surroundings can be accurately predicted in terms of the concentrations of added scatterers and, assuming all scatterers are of the same type, the contrast will be completely independent of frequency. Use of the fungicide thimerosal eliminates deterioration, and ultrasonic properties have been shown to be stable over 2.5 years.

Automated screening method for determining optimum preservative systems for personal and home care products

A procedure was designed to determine the minimum preservative level (MPL) for personal and home care products. A highly preserved sample and an unpreserved sample were combined at different concentrations within a 96-well microtiter plate by using an autodilutor. A unique tip design made it possible to accurately deliver viscous test materials that cannot be dispensed using vacuum- or fluid-filled systems. After inoculation, the sample was evaluated at a specified time interval for the presence of surviving bacteria, yeast, and mold. The lowest concentration of preservative with no microbial growth is the recommended level of preservative for the product. Because sample turbidity may interfere with determination of the endpoint, a colorimetric endpoint was used to indicate growth of microorganisms and to differentiate product from growth. The predicted levels were tested with a modified Cosmetic, Toiletry, and Fragrance Association method. The method successfully predicted effective preservative levels in many personal and home care products with a broad range of viscosities.

Saline with benzyl alcohol as intradermal anesthesia for intravenous line placement in children

BACKGROUND

It has been suggested that saline with benzyl alcohol preservative has anesthetic properties when injected intradermally. We compared the pain associated with intravenous line (i.v.) placement in patients who received intradermal lidocaine, intradermal saline + benzyl alcohol preservative, or no anesthesia.

METHODS

We performed a prospective randomized clinical trial in a convenience sample of children over 6.8 years old seen in the emergency department of a large, urban children's hospital. Children received either intradermal saline with 0.9% benzyl alcohol preservative, intradermal lidocaine, or no anesthesia prior to i.v. placement. The patient recorded the pain of the entire procedure on a visual analog scale. In the two groups that received an intradermal injection, the patient also recorded the pain of the first and second injection on a similar scale.

RESULTS

Ninety-nine children were studied, 33 in each group. Pain scores were not normally distributed. The median pain scores in millimeters for the entire procedure were 41.0 (interquartile range, 11 to 62) in the nonanesthetic group, 9.0 (interquartile range 3 to 37) in the saline with benzyl alcohol group, and 10.0 (interquartile range, 4 to 32) in the lidocaine group (P = 0.006 for saline vs nonanesthetic, P = 0.04 for lidocaine vs nonanesthetic, P = 0.57 for saline vs lidocaine). There was no difference between groups with regard to baseline anxiety, demographic characteristics, size of i.v. inserted, number of i.v. attempts, or pain upon intradermal injection.

CONCLUSION

Saline with benzyl alcohol and 1% lidocaine are equally effective as intradermal anesthetics for i.v. line placement in children, and are both more effective than no anesthesia.

Analgesic efficacy and safety of nonpreserved ketorolac tromethamine ophthalmic solution following radial keratotomy. Ketorolac Radial Keratotomy Study Group

PURPOSE

To compare the analgesic efficacy and safety of nonpreserved ketorolac tromethamine 0.5% with those of its vehicle in the treatment of postsurgical ocular pain following radial keratotomy.

METHODS

This study employed a multicenter, double-masked, randomized, parallel-group design. Radial keratotomy patients were treated with either nonpreserved ketorolac tromethamine 0.5% or its vehicle four times daily for up to 3 days following surgery. Patients were provided with an escape medication (acetaminophen) for use only as needed for intolerable pain.

RESULTS

Patients treated with ketorolac reported significantly greater pain relief (P < or =.023), less pain intensity (P < or =.047), less use of escape medication (P < or =.001), fewer symptoms of ocular discomfort (P=.024), and fewer sleep disturbances (P < or =.013) than did patients treated with vehicle. No treatment-related adverse events were reported in the ketorolac group, and only one treatment-related adverse event was reported in the vehicle group. Most other safety findings were equivalent in the two treatment groups except that there were significantly less eyelid erythema (P=.026) and eyelid edema (P < or =.001) in the ketorolac group.

CONCLUSIONS

Nonpreserved ketorolac tromethamine 0.5% ophthalmic solution was significantly more effective than, and as safe as, vehicle in the treatment of postoperative pain associated with radial keratotomy. Therefore, topical ketorolac may be a valuable treatment option for the maintenance of patient comfort following refractive surgery.

Preservative-free lidocaine 1% anterior chamber irrigation as an adjunct to topical anesthesia

PURPOSE

To evaluate the effect on the central corneal endothelium of anterior chamber irrigation with preservative-free lidocaine 1% as an adjunct to topical anesthesia during phacoemulsification.

SETTING

Department of Ophthalmology, Hospital Capuchos, Lisbon, Portugal.

METHODS

This prospective, randomized controlled study comprised 59 eyes. Thirty-one eyes had phacoemulsification (in-the-bag cracking technique) under topical anesthesia with anterior chamber irrigation by preservative-free lidocaine 1%. Twenty-eight eyes having the same procedure but with local-regional anesthesia served as the control group. All eyes had preoperative and postoperative specular microscopy and computer-assisted morphometry. A Student's t-test was used for between-group comparison of the following parameters: patient age, central corneal endothelial cell loss, mean endothelial cell size variation, and phacoemulsification ultrasound time Follow-up was 4 weeks.

RESULTS

The between-group differences in mean patient age and ultrasound time were not significant. The differences between groups in the endothelial cell parameters were also not significant. Mean postoperative endothelial cell loss was 3.59% +/- 2.79 (SD) in the topical anesthesia group and 4.37 +/- 2.00% in the control group. Mean variation in cell size was 3.71 +/- 1.57% and 3.79 +/- 1.07%, respectively.

CONCLUSION

Intracameral infusion of preservative-free lidocaine 1% had no effect on the corneal endothelial cell loss rate or mean cell size variation in this short-term assessment.

Stability of cefazolin sodium eye drops

OBJECTIVE

Assessing the stability of cefazolin sodium in preservative-free and preservative-containing eye drops.

METHOD

Extemporaneous formulations of eye drops were prepared from a commercially-available parenteral product of cefazolin sodium: eye drops 'A' contained 50mg/ml of cefazolin sodium in 0.45% w/v sodium chloride solution, and eye drops 'B' contained 50 mg/ml, 0.005% w/v thiomersal and 1% w/v glycerol in water-for-injection. Cefazolin sodium concentrations in these eye drops were monitored by a stability-indicating HPLC assay method. Measurements of pH and osmolality, as well as tests for microbial contamination, were conducted.

RESULTS

The eye drops stored at 4 degrees C were stable for 42 days with minimal changes in pH and osmolality, but eye drops stored at room temperature were only stable for a few days with greater increments in pH and osmolality. None of the samples cultured had bacterial or fungal growth after 7 days of incubation.

CONCLUSION

Extemporaneously prepared formulations of cefazolin are unstable at room temperature and should be stored in a refrigerator.