Antibiotic lock: in vitro stability of gentamicin and sodium citrate stored in dialysis catheters at 37 degrees C.

Catheter-related bacteremia (CRB) is a major cause of morbidity and mortality especially among patients receiving hemodialysis. Antibiotic lock therapy represents a promising technique in the treatment of CRB. Several studies have evaluated antibiotics in combination with heparin as an interdialytic locking solution for prophylaxis of CRB. The objective of this study was to evaluate the stability of gentamicin and sodium citrate in hemodialysis catheters as an interdialytic lock. Solutions containing gentamicin 2.5 mg/mL and sodium citrate 40 mg/mL (4%) were prepared individually and in combination. The solutions were instilled into dialysis catheters and stored at 37 degrees C for 96 h. Samples were withdrawn randomly from catheter lumens at 24-hour intervals for 4 days and stored at -20 degrees C until analysis. The samples were analyzed with validated, stability-indicating HPLC assays. The luminal concentration of gentamicin 2.5 mg/mL, sodium citrate 40 mg/mL (4%), and the combination was determined on study days 0, 1, 2, 3, and 4. When gentamicin was combined with sodium citrate and stored at 37 degrees C in dialysis catheters, the solution showed no decrease in either the gentamicin or the sodium citrate concentrations over the 96-hour study period. The percent of the original concentration at 96 h was 102.4+/-1.03 for gentamicin and 102.9+/-1.25 for citrate (P=0.5556). The combination of gentamicin 2.5 mg/mL and sodium citrate 40 mg/mL (4%) can be retained in hemodialysis catheters for at least 96 h at 37 degrees C with no evidence of degradation.

Stability of trisodium citrate and gentamicin solution for catheter locks after storage in plastic syringes at room temperature.

BACKGROUND: Catheter-related infections are a major problem for hemodialysis patients with central venous catheters for vascular access. Catheter lock solutions containing an anticoagulant are used to maintain the patency of the catheter between hemodialysis sessions. There is evidence that the use of lock solutions containing an antibiotic is associated with lower rates of infection but also that these solutions can kill microbes in colonized catheters and thus avoid the risks and costs associated with replacing the catheter. OBJECTIVE: This stability study was conducted to determine whether an extemporaneously prepared gentamicin-citrate catheter lock solution would retain its potency over time, thus allowing for advance preparation of the solution. METHODS: Catheter lock solutions containing gentamicin alone, citrate alone, and the combination of gentamicin and citrate were prepared aseptically and packaged in polyethylene syringes. The syringes were stored at room temperature. At timed intervals over 112 days, samples were withdrawn for analysis by means of validated high-performance liquid chromatography. RESULTS: None of the 3 lock solutions showed any evidence of degradation during the 112-day observation period. In the formulation containing both gentamicin 2.5 mg/mL and sodium citrate 40 mg/mL (4%), there was no change in the concentration of either gentamicin (p = 0.34) or citrate (p = 0.55). Linear regression analysis of the concentration-time data for the combined formulation showed that 99.97% of the labelled amount of gentamicin and 101.30% of the labelled amount of citrate remained at day 112. The lower limit of the 95% confidence intervals indicated that more than 98.17% of the gentamicin and more than 99.57% of the citrate remained on day 112. CONCLUSION: The results of this study will allow pharmacies to extemporaneously compound the combined gentamicin-citrate catheter lock solution in advance of use. The method described here will yield a stable product for use in clinical applications.

Safety and efficacy of an ocular insert for apomorphine-induced emesis in dogs.

OBJECTIVE: To evaluate the safety and efficacy of an ocular insert designed to provide controlled release of apomorphine for the induction of emesis in dogs. ANIMALS: 5,001 dogs treated with ocular apomorphine inserts and 32 dogs treated with IV administration of apomorphine. PROCEDURES: Data collected on a case report form included breed, body weight, time to emesis after placement of the insert, and any information available regarding the nature of the toxicosis and clinical signs. A list of potential adverse effects was provided, and attending clinicians graded their occurrence by use of a subjective scale. Similar report forms were used for dogs that received apomorphine IV. Treatment was considered successful if emesis occurred within 15 minutes of administration. Safety was assessed by evaluation of the frequency and severity of adverse effects. RESULTS: For the ocular insert and IV injection groups, the success rates were 83.5% and 90.6% respectively, and were not significantly different. Adverse effects were more frequent in the IV group, whereas ocular irritation was most frequent in the insert group. CONCLUSIONS AND CLINICAL RELEVANCE: Overall, the ocular inserts provided an alternative to parenteral administration of apomorphine with comparable efficacy and a lower prevalence of adverse effects.