Penetration of oral and topical ciprofloxacin into the aqueous humour

Triangulation of pharmacoepidemiology and laboratory science to tackle otic quinolone safety

Background

The scientific method requires studies with high internal and external validity. Though both are necessary, they do not go hand‐in‐hand: The more controlled a study is to enhance internal validity, the less applicable to real‐world clinical care, and vice versa. In the many instances where evidence from clinical trials is not available, scientific inference must rely on more extreme approaches on this spectrum, such as mechanistic (limited generalizability/strong bias control) and real‐world evidence (RWE) studies (higher generalizability/lesser bias control).

Objectives

Illustrate how triangulating mechanistic and RWE studies can enhance scientific inference by delivering the supporting evidence for both.

Methods

We describe our research on an unexpected and highly unlikely drug safety issue: the risk of tympanic membrane (TM) perforations resulting from otic quinolone therapy. Tightly controlled laboratory studies using cell culture and rodent models were complemented with pharmacoepidemiological studies of real‐world data to translate mechanistic findings and corroborate RWE.

Results

We present a cascade of mechanistic and RWE studies investigating fibroblast cytotoxicity, delayed healing of perforated TMs, and spontaneous TM perforations after otic quinolone exposure, all suggesting local tissue toxicity.

Conclusion

Triangulation of mechanistic and RWE studies allowed incremental progress toward robust evidence on otic quinolone toxicity.

Analysis of pharmaceuticals and small molecules in aqueous humor

Aqueous humor (AH) is a transparent fluid found in the anterior chamber of the eye. The circulating AH nourishes the cornea and lens and removes the metabolic waste moving through the ocular chambers and drains from the eye to the venous blood. Analysis of drugs in AH is necessary to evaluate their pharmacokinetics parameters, which may be crucial to avoid potential adverse effects. Analysis of endogenous components of AH may help to understand its physiology as well as changes evoked by pathological situation. This review describes analytical methods used for determination of pharmaceuticals and small endogenous molecules in AH, focusing on sample preparation procedures and analytical techniques. Studies on human and animal samples are included. After inspection and filtering of records found in PubMed about 100 research papers were selected to review. In these articles AH samples of human and rabbit origin were studied most often. Sample evaporation and reconstitution in smaller solvent volume was the most popular method for analyte pre-concentration. Acetonitrile, methanol or mixture of both solvents were used most often for protein precipitation.

An Exploratory Microdialysis Study to Assess the Ocular Pharmacokinetics of Ciprofloxacin Eye Drops in Rabbits

PURPOSE

Despite the high frequency of use, data regarding the ocular in vivo pharmacokinetics (PK) of topically applied antibiotics are sparse. This study seeks to investigate the PK of the widely used fluoroquinolone ciprofloxacin by means of in vivo microdialysis.

METHODS

Twelve New Zealand white rabbits were included in the experiments. Under general anesthesia, microdialysis probes were implanted in the anterior chamber and the posterior segment of the same eye. After a period of 90 min after implantation, one drop of ciprofloxacin was administered onto the ocular surface. Microdialysis samples of the anterior chamber and the vitreous were collected every 30 min for 6 h. Relative recovery was assessed by retrodialysis to calculate absolute concentration values. Samples were analyzed using HPLC.

RESULTS

In the anterior chamber, the maximum total drug concentration (Cmax) amounted to 0.373 ± 0.281 μg/mL and was reached (Tmax) after 116 ± 36 min. Calculated area under the concentration-time curve AUC(0-n) for ciprofloxacin in the anterior chamber was 78.8 ± 47.1 μg min/mL. For the vitreous, Cmax was 0.02 ± 0.03 μg/mL and maximum drug concentration was reached 107 ± 60 min after topical administration. AUC(0-n) for ciprofloxacin in the vitreous was 0.269 ± 0.370 μg min/mL.

CONCLUSION

Microdialysis is a suitable method to assess in vivo pharmacokinetic profiles in the anterior chamber and in the vitreous. In the anterior chamber, maximum drug concentration was reached ∼2 h after single drug administration. Although the drug concentration in the vitreous was considerably lower, time course of drug concentration was comparable.

Ciprofloxacin Decreases Collagen in Mouse Tympanic Membrane Fibroblasts

Objectives

To determine how collagen production by tympanic membrane fibroblasts is affected by ciprofloxacin at levels found in eardrops.

Study Design

Prospective, controlled, and blinded cell culture study.

Setting

Academic tertiary medical center.

Subjects

Cell culture of mouse fibroblasts.

Methods

A primary fibroblast culture was established from mouse tympanic membranes. Fibroblasts were cultured until they were 75% confluent, then treated with dilute hydrochloric acid (control) or ciprofloxacin (0.01% or 0.3%) for 24 or 72 hours for Western blotting and for 24 or 48 hours for cytotoxicity assay. Cells were observed with phase-contrast microscope. Western blotting was performed for collagen type 1 α1 (collagen 1A1) and α-tubulin.

Results

Fibroblasts treated with 0.01% and 0.3% ciprofloxacin for 24 hours had lower levels of collagen 1A1 ( P = .0005 and P < .0001, respectively) and α-tubulin (both P < .0001) than control fibroblasts. Collagen 1A1 and α-tubulin levels were lower in fibroblasts treated with 0.3% than with 0.01% ciprofloxacin ( P = .02 and P = .014). After 72 hours, 0.3% ciprofloxacin completely eliminated collagen 1A1 and α-tubulin ( P < .001). Cells treated with 0.01% ciprofloxacin for 72 hours also had lower collagen 1A1 ( P < .0001) and α-tubulin ( P = .005) as compared with the control. Seventy-two-hour incubation in 0.01% or 0.3% ciprofloxacin resulted in lower levels of collagen 1A1 ( P = .009 and P < .0001, respectively) and α-tubulin ( P = .007 and P < .0001, respectively) than 24-hour incubation. Cytotoxicity assay and phase-contrast microscopy mirrored these findings.

Conclusions

Treatment of tympanic membrane fibroblasts with 0.3% ciprofloxacin, as found in eardrops, reduces fibroblast viability and collagen and α-tubulin protein levels. These findings could explain tympanic membrane healing problems associated with quinolone eardrops.

Antibiotic prevention of postcataract endophthalmitis: a systematic review and meta-analysis

Endophthalmitis is one of the most feared complications after cataract surgery. The aim of this systematic review was to evaluate the effect of intracameral and topical antibiotics on the prevention of endophthalmitis after cataract surgery. A systematic literature review in the MEDLINE, CINAHL, Cochrane Library and EMBASE databases revealed one randomized trial and 17 observational studies concerning the prophylactic effect of intracameral antibiotic administration on the rate of endophthalmitis after cataract surgery. The effect of topical antibiotics on endophthalmitis rate was reported by one randomized trial and one observational study. The quality and design of the included studies were analysed using the Cochrane risk of bias tool. The quality of the evidence was evaluated using the GRADE approach. We found high-to-moderate quality evidence for a marked reduction in the risk of endophthalmitis with the use of intracameral antibiotic administration of cefazolin, cefuroxime and moxifloxacin, whereas no effect was found with the use of topical antibiotics or intracameral vancomycin. Endophthalmitis occurred on average in one of 2855 surgeries when intracameral antibiotics were used compared to one of 485 surgeries when intracameral antibiotics were not used. The relative risk (95% CI) of endophthalmitis was reduced to 0.12 (0.08; 0.18) when intracameral antibiotics were used. The difference was highly significant (p < 0.00001). Intracameral antibiotic therapy is the best choice for preventing endophthalmitis after cataract surgery. We did not find evidence to conclude that topical antibiotic therapy prevents endophthalmitis.

Liberação intraocular de ofloxacina associada a lente de contato biossintética em ceratite bacteriana experimental em cães

Avaliou-se a concentração de ofloxacina liberada por uma lente de contato de membrana de celulose biossintética, para tratamento de ceratite bacteriana experimental em cães, pela inoculação de Staphylococcus aureus intraestromal. Comparou-se o tratamento com a lente de contato biossintética impregnada com ofloxacina à terapia tópica convencional. Realizou-se avaliação microbiológica e dosagem de ofloxacina no humor aquoso por meio do método de cromatografia líquida de alto rendimento (HPLC). Houve diferença estatística na contagem de colônias bacterianas entre os olhos com ceratite e os demais grupos, no primeiro dia de coleta. O biomaterial, impregnado com ofloxacina, promoveu liberação gradual durante o período de avaliação, aos três e sete dias; no terceiro dia, o grupo tratado com a lente de contato obteve mediana de 3,72μg/mL, enquanto o grupo tratado com colírio resultou em 49,56μg/mL. Apesar do valor inferior, o grupo com lente de contato atingiu a concentração inibitória mínima, sendo eficaz no controle da infecção bacteriana.

Single-dose oral ciprofloxacin compared with single-dose intravenous cefazolin for prophylaxis in inguinal hernia repair: a controlled randomized clinical study

The aim of this study was to compare the efficacy of single-dose intravenous cefazolin prophylaxis with single-dose oral ciprofloxacin prophylaxis in patients undergoing tension-free inguinal hernia repair with polypropylene mesh. In a prospective and randomized setting, 395 patients received either a single dose of 500 mg of ciprofloxacin orally, 1--2h before the operation, or a single dose of 1g cefazolin intravenously on induction of anaesthesia. The primary outcome was to determine the wound infection rate within one year. The overall infection among the entire study population was 2% (eight of 395) including 2% (four of 199) of those receiving intravenous cefazolin and 2% (four of 196) of those treated with oral ciprofloxacin. There was no statistically significant difference between groups (P=0.59). All the infections were superficial incisional surgical site infections, and none progressed to a deep infection. Escherichia coli was the most commonly isolated bacterium. None of the infected patients developed recurrence of hernia. The rate of recurrence was 1.3% (five of 395) at one year including 2% (four of 199) of those receiving cefazolin and 0.5% (one of 196) of those receiving ciprofloxacin. Oral ciprofloxacin prophylaxis was found to be an attractive option with its wide antibacterial spectrum, low cost and ease of administration in patients undergoing tension-free inguinal hernia repair with polypropylene mesh.