Epistaxis associated with elevation of INR in a patient switched to generic warfarin

Phosphodiesterase-5 Inhibitor Use: An Under-Reported Cause of Profuse Nasal Bleeding

BACKGROUND

Phosphodiesterase-5 (PDE-5) inhibitors enhance penile erection and have gained popularity not only for erectile dysfunction, but also in recreational settings. Nevertheless, adverse effects have been associated with their use, with nasal bleeding among them. PDE-5 inhibitor action is materialized through the inhibition of the cyclic guanosine monophosphate (cGMP) enzyme. cGMP is present at several sites of the human body in addition to the corpus cavernosum, leading to the adverse effects associated with its nonselective inhibition.

CASE REPORTS

Two male patients with severe epistaxis who were taking PDE-5 inhibitors for erectile dysfunction or recreational purposes are discussed. Surgical intervention was required in both patients to control the nasal hemorrhage. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Nasal bleeding in patients who are taking PDE-5 inhibitors might represent an under-reported cause of epistaxis because of the unwillingness of most male patients to discuss issues pertaining their use without hesitation. Yet such episodes are rather profuse. This is especially true when the venous engorgement caused in the nasal mucosa by the smooth muscle relaxant effect of PDE-5 inhibitors is combined with a second event (e.g., specific drugs or blood dyscrasia). Emergency physicians should be also aware of the possibility that in the coming years the number of such cases might increase because of the increased use of these medications for erectile dysfunction or recreational purposes. It is likely that these patients could not be managed conservatively, but would rather require referral to an Ear, Nose, and Throat Department for surgical intervention.

Study of hemostasis procedures for posterior epistaxis

OBJECTIVE

Hemostasis is difficult in patients with bleeding emanating from the deep regions in the nasal cavity; however, there is no standard treatment method. We studied hemostasis procedures in patients who visited our outpatient department and presented with idiopathic epistaxis extending from the posterior nasal cavity to Kiesselbach's area.

METHODS

The subjects were patients with epistaxis who visited our hospital between June 2008 and May 2010. We asked specific questions at the time of the hospital visit and examined patients using a nasal speculum, a flexible endoscope, and a rigid endoscope (0 or 70 degree) to identify bleeding sites. Hemostasis using electrocoagulation was selected as the first-line therapy for patients in whom a bleeding point had been identified, whereas hemostasis using a gauze tampon was performed in patients in whom the bleeding point was unknown. The subjects were analyzed by multivariate logistic regression analysis.

RESULTS

The bleeding point was unknown in most cases of recurrent posterior epistaxis. Electrocoagulation was the best hemostasis procedure. Identifying the bleeding points as much as possible and performing electrocoagulation at these sites was the preferred procedures.

CONCLUSION

We propose the treatment procedure for refractory epistaxis. When it is difficult to identify a bleeding point in a patient with refractory epistaxis due to a deviated nasal septum, a bleeding point should be identified after septoplasty; for bleeding from the sphenopalatine artery region, electrocoagulation or endoscopic cauterization of the sphenopalatine artery should be performed.

Substituting Warfarin Products: What's the Source of the Problem?

Many clinicians have expressed concerns about the bioequivalence of warfarin products, and data suggest that substituting warfarin products may increase the risk of major bleeding and thromboembolic complications. Anecdotal reports and some retrospective studies have reported differences in anticoagulation control after a warfarin product substitution. But the best available evidence—prospective, randomized, blinded clinical trials—has failed to validate these observations. Indeed, interpatient and intrapatient variability in anticoagulation control observed before and after warfarin product substitution is very similar. So, while differences in product standardization, bioavailability, and bioequivalence make a convenient explanation, the problem lies elsewhere. Perhaps poor communication, fractionated systems of care, and errors are the culprits.

Improved Stability in INR with Coumadin for a Patient Requiring Very Low Warfarin Doses

Objective:

To describe a patient who required very low doses of warfarin but who could not achieve therapeutically stable anticoagulation until treatment was switched from generic to branded warfarin.

Case Summary:

A 53-year-old male with a history of hypertension, coronary artery disease, heart failure, and mild renal insufficiency was diagnosed with atrial fibrillation during a routine examination. Anticoagulation was started with warfarin 5 mg daily. The patient presented to the anticoagulation clinic 2 days later with an international normalized ratio (INR) of 5.4 and no signs or symptoms of bleeding. Warfarin was held for 3 days until the INR was <3. Warfarin was then restarted at 2.5 mg daily. Over the next week his INR rose to 4.8; warfarin was again held and restarted at 1.5 mg/day. Although the warfarin dose was eventually titrated to 6.5 mg/wk, the INR never stabilized and the patient only had consecutive therapeutic INRs twice in 1 year and only one 3-month period with therapeutic INRs not requiring any dosage adjustments. The decision was made to switch from the generic product to Coumadin to try to improve stability. Several dosage adjustments were made over the 6 weeks following the switch before the INR was stabilized with 7 mg/wk. Subsequent INRs ranged from 2.0 to 2.2 in the 3 months after the switch, during which time INRs were measured at least weekly. Over 14 months after the switch, the patient did not have an INR outside of the therapeutic range.

Discussion:

Many patients are able to take generic warfarin without problems. However, case reports have documented occasional patients who have had problems after switching to a generic product. Large cohorts have been switched to generic warfarin without experiencing significant changes in therapeutic control. However, 1 cohort study found that patients who required very low warfarin dosages had significant changes in their INR after switching to a generic product.

Conclusions:

Patients who require very low warfarin dosages to consistently maintain therapeutic anticoagulation may experience less therapeutic stability while on a generic product.

Evaluation of the clinical and economic impact of a brand name-to-generic warfarin sodium conversion program

BACKGROUND

Substitution of generic warfarin initially was discouraged because of concerns regarding therapeutic failure or toxicity. Although subsequent research with AB-rated (i.e., bioequivalent) warfarin did not confirm initial concerns, the issue is not settled for all clinicians.

OBJECTIVES

We sought to provide additional information regarding the clinical and economic impact of warfarin conversion by analyzing a real-life sample of patients receiving long-term anticoagulation therapy who were switched from brand name to generic warfarin.

METHODS

Patients who had been taking warfarin for at least 180 days and had received uninterrupted oral anticoagulation 90 days before and 90 days after switching to generic warfarin were included. The switch date was based on the first time generic warfarin was dispensed from our pharmacies. The primary end point was the calculated amount of time each patient's international normalized ratio (INR) values were within the patient-specific target INR range in the 90 days before and after the switch. Data regarding adverse events and medical resource utilization were also collected. Pharmacoeconomic analyses were performed.

RESULTS

The analysis included 2299 patients. The overall difference in calculated time INR values were below (22.6% before vs 26.1% after switch, p<0.0001) and within (65.9% before vs 63.3% after switch, p=0.0002) the therapeutic INR range was statistically but not clinically significant. Only 28.0% of patients experienced a change in therapeutic INR control of 10% or less, 33.1% experienced INR control that improved by greater than 10%, and 38.9% experienced INR control that worsened by more than 10%. The difference in total treatment costs associated with brand name and generic warfarin was 3128 dollars/100 patient-years in favor of the generic product. Sensitivity analyses revealed that cost savings associated with warfarin conversion in this health care system were highly dependent on the difference between warfarin costs and cost of treating anticoagulation-related adverse events.

CONCLUSIONS

Most of these patients were successfully switched from brand name to generic warfarin. However, supplemental INR monitoring is warranted when one warfarin product is substituted for another to allow timely detection of those patients who experience significant changes in anticoagulation response.

Substitution of generic warfarin for Coumadin in an HMO setting

BACKGROUND

Substitution of generic warfarin for Coumadin presents safety concerns due to warfarin's narrow therapeutic index and because a prior generic formulation was removed from the US market after it was associated with adverse events.

OBJECTIVE

To determine whether a health maintenance organization (HMO) can add generic warfarin to its formulary without adversely affecting warfarin management or increasing adverse events.

DESIGN

In a prospective, observational study, an HMO that formerly dispensed only Coumadin added a generic warfarin preparation (Barr Laboratories, Pomona, NY) to its formulary.

SETTING

An anticoagulation service (ACS) affiliated with an HMO that was based in St. Louis, MO.

PARTICIPANTS

The cohort consisted of 182 enrollees in the ACS as of May 1, 1999. At the start of the study, these participants were taking Coumadin; by October 31, 2000, all had switched to Barr warfarin.

MEASUREMENTS AND MAIN RESULTS

We collected data 8 months prior to and 10 months after the introduction of generic warfarin for the following endpoints: international normalized ratio (INR) control, frequency of INR monitoring, number of dose changes, and rate of thrombotic and hemorrhagic events. Statistical process control charts were used to differentiate between random variation in the endpoints and changes due to different warfarin formulations, and we used the Wilcoxon signed-rank test to look for a change in any endpoint after patients changed to generic warfarin. No significant differences were found in any endpoint.

CONCLUSIONS

Substitution of Barr warfarin for Coumadin did not significantly affect INR control, warfarin management, or adverse events. Our findings suggest that HMOs can safely substitute at least 1 generic formulation of warfarin without extra monitoring.

Subtherapeutic INR values associated with a switch to generic warfarin

OBJECTIVE

To discuss the effect on the international normalized ratio (INR) when patients are converted from therapy with Coumadin to generic warfarin.

CASE SUMMARY

Two cases at a family medicine center anticoagulation clinic in Oklahoma City, OK, in which subtherapeutic INR values occurred after a switch from Coumadin to generic warfarin, while all other variables were kept consistent demonstrate the need for close monitoring of the INR when patients are switched between brands of warfarin.

DISCUSSION

Warfarin is a narrow therapeutic index drug since small changes in systemic concentration can lead to significant variation in phamacodynamic response. In March 1997, the Food and Drug Administration (FDA) approved generic warfare based on the FDA and United States Pharmacopoeia (USP) standards. Due to different specifications between Dupont Pharma and the USP, content uniformity may differ between brand and generic forms of warfarin. United studies have demonstrated bioequivalence between brand and generic. The two cases presented demonstrate the potential for fluctuations in the INR when switching between generic and brand. Thus, these eases illustrate the need for close monitoring if a change is made.

CONCLUSIONS

While considered bioequivalent by the FDA, switching between Coumadin and generic warfarin may lead to significant changes in the INR, warranting dose alterations due to different content uniformity specifications between Dupont Pharma and the USP. Patients switching between Coumadin and generic warfarin should have their INR monitored more carefully.

A randomized, crossover comparison of warfarin products in the treatment of chronic atrial fibrillation

OBJECTIVE

To compare the dosing requirements and international normalized ratios (INRs) associated with two bioequivalent crystalline warfarin sodium products in patients with chronic atrial fibrillation.

METHODS

A multicenter, single-blind (prescriber), randomized, crossover evaluation of Apothecon warfarin and DuPont warfarin (Coumadin) was conducted in consenting adults with chronic or paroxysmal atrial fibrillation who had been receiving DuPont warfarin chronically for the prevention of thromboembolism. Patients were randomly assigned to initially either continue DuPont warfarin or receive Apothecon warfarin for four weeks, with weekly evaluation of dosage and INR changes, safety, and efficacy. Subsequently, patients crossed over and received the other product for four weeks.

RESULTS

There were 113 patients randomized to receive study treatment. Neither the propensity for a dosage change or an INR change nor the magnitude of a dosage change or INR change appeared related to a particular warfarin product (NS for each variable after each study period). After four weeks of treatment, the same number of patients (n = 7) experienced a > or = 20% change in warfarin dosage from the respective baseline with each product. The number of patients with INRs outside the desired protocol range after four weeks of treatment was similar for both groups (< 1.8, n = 9 for both products, or > 3.2, n = 9 for DuPont, n = 10 for Apothecon). No major hemorrhagic or thromboemoblic events occurred.

CONCLUSIONS

The results of this study show that Apothecon warfarin and DuPont warfarin provide equivalent anticoagulation in patients with chronic or paroxysmal atrial fibrillation.