Flavoxate: What Is It and What's it For?

Flavoxate is a drug used to treat constant and troublesome bladder contractions. It addresses the different symptoms in those with overactive bladder syndrome.

Written and verified by el biólogo Samuel Antonio Sánchez Amador.

Last update: 21 May, 2023

Flavoxate is an anticholinergic drug with muscarinic effects. Its use is very specific, as it’s used to treat overactive bladder, a condition in which the muscles of the bladder contract uncontrollably, causing frequent urination, an urgent need to urinate, and difficulty controlling urination.

It should be noted that flavoxate is the active substance of the drug, but it isn’t found under this designation in pharmacies. Some of their trade names are Uronid ®, Urispas ®, Bladderon ®, Bladuril ®, and Genurin ®.

Flavoxate is prescribed for the symptomatic relief of interstitial cystitis, dysuria, incontinence, prostatitis, urethritis, urocystitis, and other tissue problems in the excretory system. If you want to know more, keep reading.

What is flavoxate used for?

Overactive bladder syndrome (OAB) is defined as an urge to urinate, with or without incontinence, usually with nocturia, in the absence of an underlying metabolic or pathologic disorder. As indicated by the European Review for Medical and Pharmacological Sciences, this condition affects up to 32% of the general population.

As we have said, flavoxate is a drug specially designed to treat OAB. This was the first antispasmodic drug approved by the Food and Drug Administration (FDA) to address overactive bladder syndrome and is widely used in the medical field.

Studies cited above highlight that the use of flavoxate in overactive bladder syndrome improves symptoms in 55 to 83.4% of patients compared to a placebo. This shows that it isn’t effective in each and every one of the conditions in which it’s administered, but it’s much better than other pharmacological options.

Mechanism of action

Flavoxate is administered in the form of a prodrug (flavoxate hydrochloride); it’s transformed into its active form within the patient’s body. This compound exerts an inhibition of phosphodiesterases, a moderate calcium antagonist activity, and a local anesthetic effect.

In particular, phosphodiesterase enzymes perform an essential function on the detrusor muscle of the urinary bladder, favoring its contraction. Therefore, the administration of flavoxate hydrochloride is linked to a lower activity of this muscle tissue, which reduces the symptoms of OAB.

It’s also necessary to emphasize that flavoxate is a calcium antagonist. Without going into too much detail, it can be said that it suppresses the concentrations mediated by calcium ions (Ca2 +) in the fibers of the detrusor muscle in a competitive and non-competitive way.

In its intravenous variant, it’s also capable of inhibiting bladder contraction in the different phases induced by pelvic nerve stimulation.

General uses

To finish exploring the pharmacodynamics of flavoxate, here are the uses cited by its leaflets:

• Intermittent urination: Starts and stops during the act of urinating with difficulty, at the beginning of urination.
• Urinary urgency: The repeated need to go to the bathroom.
• Abnormal urinary frequency: Most people urinate 6 to 7 times in a 24-hour period. People with OAB have an irrepressible and repeated urge to go to the bathroom.
• Nocturia: The person needs to go to the bathroom repeatedly at night.
• Treatment of suprapubic bladder pain.
• Treatment of urinary incontinence.

These types of conditions are much more frequent in the aging population. For example, overactive bladder syndrome affects up to 40% of the world’s population over 75 years of age.

How is flavoxate administered?

Flavoxate comes as a film-coated tablet for oral intake and is typically stored in 60 units per box. Its shape is white and circular and each tablet should be swallowed whole with the help of a glass of water, without swallowing or sucking in any case.

We’re going to focus our attention on the brand Uronid 200 mg film-coated tablets ®, but this isn’t the only one. Each Uronid tablet contains 200 milligrams of flavoxate hydrochloride, but keep in mind that this concentration can vary between manufacturers and presentations.

The recommended daily dose is 1 tablet every 6-8 hours. This means that, depending on the severity of the symptoms, you should take 3 to 4 pills a day, which is equivalent to 600-800 milligrams of flavoxate hydrochloride every 24 hours. As indicated on the package insert, the tablets should always be consumed after meals.

Who shouldn’t take this medicine?

First of all, this drug shouldn’t be taken by anyone who has shown hypersensitivity reactions to flavoxate or any of the excipients in the pill. Some of these accessory compounds are the following: lactose, povidone (E-1201), modified carboxymethylcellulose (E-466), talc (E-533b), magnesium stearate (E-572), colloidal silica (E-551) and microcrystalline cellulose (E-460).

Apart from these allergies, there are other population groups in which treatment with this drug isn’t recommended. If you have any of these conditions, tell your doctor:

• Gastrointestinal diseases that affect the normal transit of food (obstructions)
• Intestinal bleeding
• Muscle inability to swallow (achalasia)
• Inability to completely empty the bladder (urinary retention)
• In conjunction with glaucoma treatments.
• Diseases that cause chronic fatigue and generalized muscle weakness (myasthenia gravis).

As reported by the United States National Library of Medicine, this drug may cause some drowsiness. Therefore, it’s recommended not to drive or use heavy machinery until the patient is used to the drug. The same applies to alcohol; taken together with flavoxate, the effect of drowsiness may be magnified.

Since the renal clearance of the active metabolite represents more than 50% of the dose, renal insufficiency can significantly affect the kinetics of the product. Therefore, caution is required in patients with renal impairment.

Pregnancy and breastfeeding

If you’re planning to become pregnant and have been prescribed a long-term treatment with Uronid ® or any of the drug brands of flavoxate, don’t hesitate to go to the doctor and consult them. The safety of this medicine during pregnancy and breastfeeding hasn’t been established, so it’s almost always best to stop taking it.

What are the possible side effects?

Like all medicines, flavoxate can cause a number of side effects. We present them to you according to the percentage of people affected at a general level:

• Common side effects (up to 1 in 10 patients): Nausea is the most common clinical sign after taking flavoxate. That said, the general population tends to tolerate it very well. To avoid gastrointestinal symptoms, it’s recommended to take the pills always after eating.
• Uncommon (up to 1 in 100 patients): Drowsiness, visual disturbances, vomiting, dry mouth, gastric pain, heavy digestion and skin rashes.
• Rare (up to 1 in 1000 patients): Hives, itching, inability to completely empty the bladder (urinary retention), and fatigue.
• Effects of unknown frequency: Hypersensitivity, anaphylactic reaction, anaphylactic shock, confusion, glaucoma, fast and irregular heartbeat, reddening of the skin, jaundice, liver disorders, and abnormal liver function test results.

If you have any type of adverse effect that interferes with your daily life, don’t hesitate to consult your doctor.

What should I do if I miss a dose?

If you forget to take a dose, skip it and move on to the next as if nothing had happened. Due to the proximity between takes (6-8 hours), it’s best to ensure you don’t forget. Never take two doses in a row to make up for forgetting.

How should I act in case of an overdose?

Flavoxate is generally well tolerated by almost all patients and the toxic dose is difficult to achieve. According to the Medicines UK (EMC) drug portal, no risk has been identified following an overdose in post-marketing experience.

Still, if you take more medicine than you should or feel sick after taking a normal dose, go to the emergency room with the box of the drug in hand. If you’re physically unwell, call an ambulance, and ask an acquaintance or neighbor to accompany you.

How to store and dispose of this medicine

This medicine doesn’t require special storage conditions as far as temperature and humidity are concerned. However, we emphasize that it must be kept out of the reach of children at all times. Its safety in children under 12 years of age hasn’t been proven and the containers don’t prevent an infant from accessing the tablets.

You shouldn’t throw this medicine in the trash or down the drain once it has expired or you don’t need it, as it contains excipients and chemicals that can be very harmful to the environment.

Final notes on flavoxate

As we have been able to verify, flavoxate is a very specific drug that’s used to address the symptoms of overactive bladder syndrome, such as the need for constant urination, nocturia, intermittent urination, and urinary incontinence.

Because these clinical signs increase in prevalence with aging, this drug is usually prescribed especially in the elderly.

Although it has a very high efficacy index, it may sometimes be necessary to accompany it with other types of pharmacological and psychological supports and changes in routine. Before starting treatment, discuss with your doctor how you can manage the symptoms.