When lifestyle changes do not help enough, your health care provider may ask you to try a prescription drug. You may take the drug alone or along with behavioral therapy. The 2 types of prescription drugs that may be recommended are, oral and intravesical drugs. There are many types of oral drugs, and the side effects range from drowsiness to upset stomach. Intravesical prescription drugs are placed directly into the bladder with a catheter. Two treatments are approved by the U.S. Food and Drug Administration (FDA) to treat IC/BPS:
Oral Pentosan Polysulfate
No one knows exactly how this drug works for IC. Many people think that it builds and restores the protective coating of the bladder tissue. It may also help by decreasing swelling or by other actions. Possible side effects are not common, but may include nausea, diarrhea and gastric distress. A small percentage of people may have temporary hair loss. It often takes at least 3 to 6 months of treatment with this drug before you notice improvement in symptoms. It is effective in relieving pain in about 30 out of every 100 patients.
Dimethyl Sulfoxide (DMSO)
The other FDA approved treatment is the placement of dimethyl sulfoxide (DMSO) into the bladder through a catheter. This is usually done once a week for 6 weeks. Some people keep using it now and then as maintenance therapy. No one knows exactly how DMSO helps interstitial cystitis. It may block swelling, decrease pain sensation and remove a type of toxin called "free radicals" that can damage tissue. Some health care providers combine DMSO with other drugs such as heparin or steroids (to decrease inflammation). No studies have tested whether these combinations work better than dimethyl sulfoxide alone. The main side effect is a garlic-like odor that lasts for several hours after using DMSO. For some patients, DMSO can be painful to place into the bladder, but the pain can often be relieved with a local anesthetic.
Hydroxyzine is an antihistamine. It is thought that some patients with IC/BPS have too much histamine in the bladder that leads to pain and other symptoms. An antihistamine may be helpful in treating IC/BPS. The main side effect is drowsiness. However, this may be a benefit because it helps the patient to sleep better at night and get up to pass urine less frequently. The only antihistamines that have been specifically studied for IC/BPS are hydroxyzine and (more recently) cimetidine. It is not known whether other antihistamines also help treat IC/BPS.
Amitriptyline is described as an antidepressant, but it actually has many effects that may improve IC/BPS. It has antihistamine effects, decreases bladder spasms, and slows the nerves that carry pain messages. Amitriptyline is widely used for other types of chronic pain such as cancer and nerve damage. The most common side effects are drowsiness, constipation and increased appetite.
Heparin is similar to pentosan polysulfate and probably helps the bladder by similar mechanisms. Heparin must be placed into the bladder with a catheter. The usual dose is 10,000 to 20,000 units daily or 3 times a week. Complications are rare because the heparin stays in the bladder only and does not usually affect the rest of the body.