From the Guidelines
Cimetidine treats interstitial cystitis by blocking histamine H2 receptors in the bladder, reducing inflammation and pain associated with this condition. The mechanism of action involves blocking the histamine receptors in the bladder wall, which are activated by mast cell activation and histamine release, leading to decreased inflammation and nerve sensitization 1.
Key Points
- Cimetidine has immunomodulatory effects that may help regulate the abnormal immune response seen in interstitial cystitis.
- The typical dosage is 400-800 mg daily, divided into 2-3 doses, with treatment courses lasting 3-6 months, though some patients may require longer therapy.
- Patients should take cimetidine with meals to reduce stomach upset and should be aware that improvement may take several weeks to become noticeable.
- Side effects are generally mild but can include headache, dizziness, and gastrointestinal disturbances.
- Patients should inform their doctor of all medications they take, as cimetidine can interact with certain drugs by affecting liver enzyme activity.
Clinical Considerations
- The treatment of interstitial cystitis/bladder pain syndrome is best identified and managed through use of a logical algorithm, as presented in the AUA guideline for the diagnosis and treatment of interstitial cystitis/bladder pain syndrome 1.
- Diagnosis and treatment methodologies can be expected to change as the evidence base grows in the future.
- The use of cimetidine in the treatment of interstitial cystitis is based on its ability to block histamine H2 receptors, which reduces inflammation and pain associated with this condition.
From the Research
Mechanism of Action of Cimetidine in Interstitial Cystitis
- The exact mechanism of action of cimetidine in the treatment of interstitial cystitis is not fully understood, but it is believed to involve the alteration of histamine-gastrin reactions mediated via H2 receptors 2.
- A study published in 2001 found that cimetidine improved symptoms in 60-70% of patients with painful bladder syndrome/interstitial cystitis, but the presence or absence of gastrin or histamine-like immunoreactivity did not explain its therapeutic benefit 2.
- The study suggested that cimetidine may have a similar mechanism of action on the human bladder as it does in the human stomach, where it alters histamine-gastrin reactions mediated via H2 receptors and a proton pump 2.
- However, the study found no evidence of gastrin-like immunoreactivity in bladder biopsies, apart from some nonspecific urothelial staining, and the presence or absence of mast cells did not correlate with the symptomatic response 2.
- Further research is needed to fully understand the mechanism of action of cimetidine in the treatment of interstitial cystitis, as the current evidence does not provide a clear explanation for its therapeutic benefits 3, 4, 5, 6.