Flavoxate hydrochloride for urinary urgency after pelvic radiotherapy: comparison of 600 mg versus 1200 mg daily dosages

Advances in the management of radiation-induced cystitis in patients with pelvic malignancies

OBJECTIVE

Radiotherapy plays a vital role as a treatment for malignant pelvic tumors, in which the bladder represents a significant organ at risk involved during tumor radiotherapy. Exposing the bladder wall to high doses of ionizing radiation is unavoidable and will lead to radiation cystitis (RC) because of its central position in the pelvic cavity. Radiation cystitis will result in several complications (e.g. frequent micturition, urgent urination, and nocturia) that can significantly reduce the patient's quality of life and in very severe cases become life-threatening.

METHODS

Existing studies on the pathophysiology, prevention, and management of radiation-induced cystitis from January 1990 to December 2021 were reviewed. PubMed was used as the main search engine. Besides the reviewed studies, citations to those studies were also included.

RESULTS AND DISCUSSIONS

In this review, the symptoms of radiation cystitis and the mainstream grading scales employed in clinical situations are presented. Next, preclinical and clinical research on preventing and treating radiation cystitis are summarized, and an overview of currently available prevention and treatment strategies as guidelines for clinicians is provided. Treatment options involve symptomatic treatment, vascular interventional therapy, surgery, hyperbaric oxygen therapy (HBOT), bladder irrigation, and electrocoagulation. Prevention includes filling up the bladder to remove it from the radiation field and delivering radiation based on helical tomotherapy and CT-guided 3D intracavitary brachytherapy techniques.

[Radiation cystitis : Pathophysiology and treatment]

Radiation cystitis (RC) is a common side-effect of radiation to the pelvis. Their clinical appearance as well as their degree of expression is manifold, as are the therapeutic options. However, in the absence of randomized examinations, recommendations are difficult. We differentiate between oral, systemic therapies, intravesical instillations and interventions as well as interventional, radiological and, as an ultima ratio, surgical treatments. This article provides an overview of the different treatment options with particular emphasis on the conservative-interventional therapy options.

A Narrative Review on the Pathophysiology and Management for Radiation Cystitis

Radiation cystitis is a recognised complication of pelvic radiotherapy. Incidence of radiation cystitis ranges from 23 to 80% and the incidence of severe haematuria ranges from 5 to 8%. High quality data on management strategies for radiation cystitis is sparse. Treatment modalities are subclassified into systemic therapies, intravesical therapies, and hyperbaric oxygen and interventional procedures. Short-term cure rates range from 76 to 95% for hyperbaric oxygen therapy and interventional procedures. Adverse effects of these treatment strategies are acceptable. Ultimately, most patients require multimodal treatment for curative purposes. Large randomised trials exploring emergent management strategies are required in order to strengthen evidence-based treatment strategies. Urologists encounter radiation cystitis commonly and should be familiar with diagnostic modalities and treatment strategies.

Flavoxate in urogynecology: an old drug revisited

INTRODUCTION AND HYPOTHESIS

Since its emergence in 1967, flavoxate has been used to treat several urogenital tract disorders irrespective of the etiology of the underlying disease, but the main indications have been overactive bladder and urge symptomatology. With the advances in anticholinergic drugs, its popularity has decreased in recent decades.

METHODS

In this review we summarize the current status of flavoxate in urogynecological practice focusing on its historical background, mechanism of action, efficacy, clinical experiences, outcomes, side effects and tolerability. We reviewed and analyze all the data and draw the major conclusions. We searched MEDLINE and the Cochrane Library using the keyword "flavoxate", and summarized review articles, original studies and case reports published from 1970 to 2013.

RESULTS AND CONCLUSION

We conclude that the minimal side effects and high tolerability of flavoxate make it worthy of consideration for the treatment of several clinical urogynecological conditions. It deserves more clinical studies to assess its efficacy as no randomized controlled trials have been performed with flavoxate during the last decade. More studies and novel drug formulations may reveal or improve its efficacy in daily practice.

Non-surgical interventions for late radiation cystitis in patients who have received radical radiotherapy to the pelvis

BACKGROUND

Chronic radiation cystitis occurs a minimum of three months after completion of pelvic radiotherapy and represents a range of clinical symptoms for which there is as yet no recommended standard management.

OBJECTIVES

The aim of this review was to identify the various non-surgical treatment options for the management of late chronic radiation cystitis and evaluate the evidence.

SEARCH STRATEGY

Synonyms for radiation therapy and for the spectrum of radiation toxicity to the bladder in both text and MeSH terms were combined and applied to a range of databases without restriction of year of publication, methodology or language.

SELECTION CRITERIA

The inclusion criteria included studies of interventions for the non-surgical management of all grades of late radiation cystitis.

DATA COLLECTION AND ANALYSIS

Out of 80 relevant studies, there were no RCTs that met the inclusion criteria, but there were three prospective case series and two non-randomised studies which assessed different interventions and were not comparable.

MAIN RESULTS

Sixty-three reports met the stated inclusion criteria. The majority were predominantly retrospective case series with the exception of two trials which were unrandomised and unblinded studies with a control group for comparison of effect. Although these two trials, Micic 1988, (intravesical placental extract) and Milani 1988, (flavoxate) provided the strongest evidence they were not randomised and were essentially isolated controlled studies.

REVIEWER'S CONCLUSIONS

In such a relatively rare condition there are obvious difficulties in identifying sufficient patients to participate in a randomised controlled trial. The number of published reports is a reflection of the degree of medical interest that exists in providing therapeutic solutions for late radiation cystitis. However, in spite of the two studies of level IIA evidence, the absence of randomised controlled trials makes it impossible to draw any firm conclusions.

A review of flavoxate hydrochloride in the treatment of urge incontinence

This article provides a review of the use of flavoxate hydrochloride in the treatment of urge incontinence. It outlines the pharmacology, mode of action, toxicology and pharmacokinetic studies which have been carried out, and then reviews the clinical studies, including those involving patients with benign prostatic hypertrophy. The effects of dosages of 600-1200 mg/day are compared, particularly regarding safety and tolerability factors. Finally, alternative therapies to flavoxate hydrochloride (alpha-adrenergic receptor blockers, oxybutinin chloride, terodiline hydrochloride, emepronium bromide and imipramine) are summarized. The article is written in the knowledge of recent evidence which indicates that flavoxate hydrochloride exhibits only weak anticholinergic activity on receptors involved in the control of the lower urinary tract.

Comparison of flavoxate hydrochloride in daily dosages of 600 versus 1200 mg for the treatment of urgency and urge incontinence

Flavoxate hydrochloride at a daily dosage of 600 mg was compared to a daily dosage of 1200 mg for the treatment of unstable bladder. Twenty-seven patients were treated for 4 weeks in a double-blind, randomized, parallel-group trial. Clinically, both schedules were equally successful. In urodynamic terms, however, particularly with respect to uninhibited detrusor contractions, 1200 mg/day was significantly superior to 600 mg/day. Tolerability was excellent for both regimens. The side-effect free treatment of urgency and urge incontinence is of paramount importance for a patient's quality of life.