From the Guidelines
Hydroxyzine helps treat interstitial cystitis by reducing inflammation and blocking histamine receptors in the bladder. The medication works because mast cells in the bladder of interstitial cystitis patients release excessive histamine, contributing to pain, urgency, and frequency. As a first-generation antihistamine, hydroxyzine blocks these histamine receptors while also providing mild sedative and anti-anxiety effects that can help with sleep disturbances common in these patients.
Key Points to Consider
- Typically prescribed at 10-25mg at bedtime initially, with gradual increases up to 25-75mg daily if needed 1.
- Treatment usually requires 2-4 weeks before noticeable improvement occurs, and patients should continue for at least 3-6 months to evaluate full effectiveness.
- Side effects may include drowsiness, dry mouth, and constipation, so it's best taken at bedtime.
- Hydroxyzine should be used cautiously in elderly patients and is contraindicated during early pregnancy.
- For optimal results, it's often combined with other treatments like dietary modifications, pelvic floor physical therapy, or other medications such as pentosan polysulfate sodium 1.
Mechanism of Action
The exact mechanism of hydroxyzine in treating interstitial cystitis is not fully understood, but it is believed to involve the blockade of histamine receptors in the bladder, which reduces inflammation and alleviates symptoms.
Clinical Guidelines
According to the AUA guideline for the diagnosis and treatment of interstitial cystitis/bladder pain syndrome, hydroxyzine is considered a treatment option for interstitial cystitis, although the evidence is limited 1.
From the FDA Drug Label
Hydroxyzine hydrochloride is unrelated chemically to the phenothiazines, reserpine, meprobamate or the benzodiazepines. Hydroxyzine is not a cortical depressant, but its action may be due to a suppression of activity in certain key regions of the subcortical area of the central nervous system. The mechanism of action of hydroxyzine in the treatment of interstitial cystitis is not explicitly stated in the provided drug label.
- The label mentions various effects of hydroxyzine, including antihistaminic, analgesic, and antiemetic effects, as well as skeletal muscle relaxation and bronchodilator activity.
- However, it does not provide information on how these effects relate to the treatment of interstitial cystitis. 2
From the Research
Mechanism of Action of Hydroxyzine in Interstitial Cystitis
- The exact mechanism of action of hydroxyzine in the treatment of interstitial cystitis is not fully understood, but it is believed to involve the inhibition of mast cell activation and the reduction of neurogenic inflammation 3, 4, 5.
- Hydroxyzine, an antihistamine, may help to alleviate symptoms of interstitial cystitis by blocking the release of histamine from mast cells, which can contribute to inflammation and pain in the bladder 5.
- The use of hydroxyzine in combination with other medications, such as pentosan polysulfate sodium, has been shown to be effective in relieving symptoms of interstitial cystitis in some patients 6, 4.
- The treatment of interstitial cystitis with hydroxyzine may be particularly beneficial for patients with a history of allergies or evidence of bladder mast cell activation 5.
Treatment Outcomes
- Studies have reported varying degrees of success with hydroxyzine treatment for interstitial cystitis, with some patients experiencing significant improvements in symptoms 6, 5.
- A study published in 1997 found that 65% of patients treated with hydroxyzine reported a 40% reduction in symptom scores, with a higher response rate in patients with a history of allergies 5.
- Another study published in 2006 found that the combination of pentosan polysulfate sodium and hydroxyzine was effective in relieving symptoms of interstitial cystitis in 48.4% of patients who completed one month of therapy 6.
Current Understanding
- Despite the availability of various treatment options, including hydroxyzine, the treatment of interstitial cystitis remains largely empirical and often ineffective 7.
- Further research is needed to understand the pathophysiological mechanisms of interstitial cystitis and to develop targeted therapies that can provide more effective relief for patients 3, 7.