Bladder instillation therapy delivers medication directly into your bladder through a thin catheter. The liquid stays in the bladder for a set time, called a dwell, and then you pass it the next time you urinate. Because the medication sits on the bladder lining instead of traveling through your bloodstream first, a small volume can do a lot of work right where the problem is.
Bayview compounds two different kinds of sterile bladder instillation to your urologist's prescription: gentamicin intravesical irrigation, used to help reduce repeated urinary tract infections in certain complex patients, and a heparin, lidocaine, and sodium bicarbonate instillation — often called a “rescue instillation” — used during flares of interstitial cystitis / bladder pain syndrome. They are different medications for different problems and are not interchangeable.
How does it work?
Gentamicin instilled into the bladder puts a high concentration of antibiotic directly on the bladder lining, where the bacteria are, while very little is absorbed into the bloodstream. That local concentration can suppress bacteria that are hard to treat by mouth, including some multidrug-resistant Gram-negative organisms, without exposing the rest of your body to an aminoglycoside antibiotic.
The rescue instillation works in a completely different way. Heparin is a glycosaminoglycan (GAG) analog — it resembles the natural protective layer that coats the inside of the bladder. When that layer is damaged, urine can irritate the bladder wall; heparin is thought to help restore the barrier and also has anti-inflammatory effects. Lidocaine numbs the sensory nerves in the bladder wall. Sodium bicarbonate makes the solution more alkaline, which shifts more of the lidocaine into the un-ionized form that can actually penetrate the bladder lining (Cvach & Rosamilia, Transl Androl Urol).
What is it used for?
Gentamicin irrigation. This is a specialist option, not a routine treatment for ordinary recurrent urinary tract infections. The 2025 AUA/CUA/SUFU guideline on recurrent uncomplicated urinary tract infections in women does not address intravesical gentamicin at all; the non-antibiotic prevention options it does cover are cranberry, D-mannose (which may not be effective), methenamine hippurate, and increased water intake (AUA/CUA/SUFU, 2025). Intravesical gentamicin is used mainly by urologists in complex situations — neurogenic bladder, people who use clean intermittent catheterization, bladder augmentation, and pediatric urology — and in infections that keep coming back or involve multidrug-resistant bacteria. The published evidence is small: the most complete review to date pooled only six studies and 166 patients, and the authors graded it level 2a evidence (Rutherford et al., Journal of Clinical Urology). Those studies reported fewer infections and blood levels of gentamicin that were almost always undetectable, but they were mostly small and uncontrolled.
Rescue instillations for interstitial cystitis / bladder pain syndrome. The American Urological Association's 2022 IC/BPS guideline says, in Statement 17, that “DMSO, heparin, and/or lidocaine may be administered as intravesical treatments.” That statement is graded as an Option — the weakest level of endorsement — with Evidence Grade C for DMSO, C for heparin, and B for lidocaine (AUA, 2022). It is an option a urologist may offer, not a proven or recommended therapy. The same guideline recommends against intravesical BCG outside of a research study (Statement 24, a Standard with Evidence Grade B).
Being straightforward about what the research shows: rescue instillations can give real short-term relief during a flare, but durable, lasting benefit is unproven, and most of the published studies were open-label without a placebo group. These instillations are not a treatment or a cure for interstitial cystitis. They are one option among many, used alongside the behavioral, physical therapy, and medication approaches described by the National Institute of Diabetes and Digestive and Kidney Diseases. Only a licensed urologist can decide whether they are appropriate for you.
How do the two instillations compare?
The two preparations Bayview compounds do different jobs. The table below describes those differences for education only, with FDA-approved DMSO included for context.
| Instillation | What is in it | What it is used for | Typical dwell |
|---|---|---|---|
| Gentamicin intravesical irrigation | Gentamicin at dilute concentrations (about 0.48–5.33 mg/mL) in 30–60 mL | Helping reduce repeated urinary tract infections in complex or resistant cases, under urology direction | Commonly instilled after the last void at night and held until the next void |
| Heparin / lidocaine / sodium bicarbonate (“rescue instillation”) | Heparin 10,000 units, lidocaine 80 mg, and sodium bicarbonate 1 mEq per 50 mL | Short-term relief during an interstitial cystitis / bladder pain flare | About 20–30 minutes, then voided |
| DMSO 50% (shown for comparison; commercially available, not compounded here) | Dimethyl sulfoxide 50% | The only FDA-approved intravesical medication for interstitial cystitis | 50 mL with a 15-minute dwell, usually every 2 weeks |
Preparations are described for education only and are not a statement that any one is better for a particular person. Your urologist selects the preparation, concentration, volume, dwell time, and schedule.
How is it used?
Use your instillations exactly as your urologist directs. Instillation therapy is started by a urologist, and the first ones are usually done in the clinic so you can be taught the technique. Many people, or a caregiver, then self-administer at home after that teaching. Empty your bladder first, wash your hands, use the catheter and technique you were shown, instill the medication slowly, and then hold it for the dwell time you were given before urinating normally.
Gentamicin irrigation is usually instilled through a catheter, or during clean intermittent catheterization, most often at night after the last void, and held until you urinate in the morning. Schedules are tapered over time. One representative published protocol runs daily for 10 days, then every other day for 4 weeks, then weekly for 2 months, then stops — but your urologist sets your own schedule.
The heparin, lidocaine, and sodium bicarbonate instillation is given in the clinic or self-administered at home, and is typically held about 20 to 30 minutes before you void. A common pattern is weekly for about six weeks during a flare, then spaced further apart. Heparin's effect on the bladder lining is gradual, and any barrier benefit may take three to six months to show.
Do not change your schedule or reuse a syringe on your own. A Bayview pharmacist is available if you have questions about your prescription.
Side effects & safety
The most common effects are local and short-lived: burning or discomfort during the instillation, urgency, a temporary pink tinge to the urine, and mild irritation for a little while afterward.
Gentamicin. Very little gentamicin is absorbed when the bladder lining is intact, but absorption rises when the lining is disrupted or inflamed, when the bladder has been enlarged or rebuilt using bowel tissue, when there is blood in the urine, after recent instrumentation, or when kidney function is reduced. In those situations your urologist may check blood gentamicin levels and kidney function. Repeated antibiotic instillation can also encourage antibiotic-resistant bacteria or yeast overgrowth.
Lidocaine. Lidocaine absorbed through an inflamed or raw bladder lining can cause body-wide effects: numbness or tingling around the mouth, ringing in the ears, dizziness, confusion, and, rarely, seizures or changes in heart rhythm. Stick to the prescribed dose, do not use other lidocaine products at the same time unless your prescriber says to, and tell your prescriber if you have liver problems or take heart rhythm medications.
Heparin. Heparin used this way acts locally and is not expected to thin the blood, but there is a theoretical bleeding concern if there is active blood in the urine, and it should be avoided if you have had heparin-induced thrombocytopenia.
The catheter itself. Catheterization can cause urethral injury, burning with urination, temporary blood in the urine, and can introduce infection; long-term repeated catheterization can lead to narrowing of the urethra.
Contact your urologist about fever, chills, or flank pain, heavy or lasting blood in the urine, being unable to urinate, new hearing changes or ringing in the ears, or pain that does not settle after an instillation.
Who should not use it?
Instillation therapy is not right for everyone. Gentamicin instillation should be avoided if you are allergic to gentamicin or other aminoglycoside antibiotics, if a previous aminoglycoside caused hearing or balance damage, or if you have an active kidney infection, which needs whole-body antibiotic treatment instead. It is also not an option if you cannot be catheterized safely.
The rescue instillation should be avoided if you are allergic to lidocaine or other amide anesthetics, and is used with caution if you have liver impairment or take class I antiarrhythmic medications. Tell your urologist about active bleeding in the urine or any history of heparin-induced thrombocytopenia.
Tell your urologist about your full health history, allergies, kidney and liver function, and all medications you take, including any other lidocaine-containing products, so they can determine whether instillation therapy is appropriate.
How should it be stored?
Refrigerate your syringes as directed on the label, and let one come to room temperature before instilling it — cold fluid in the bladder is uncomfortable. Keep syringes in their packaging, out of the reach of children, and do not share them; each syringe is prepared for one patient. Do not use a syringe that is cloudy, discolored, or leaking. Do not use it after the beyond-use date printed on your label; that date is assigned according to the USP <797> category and the testing performed for your preparation, so always follow what your label says. Dispose of unused syringes as directed by your pharmacist.
Why is this compounded?
There is no FDA-approved commercial product for either of these preparations. DMSO 50% is the only intravesical medication the FDA has approved for interstitial cystitis, and no manufacturer makes a heparin/lidocaine/bicarbonate cocktail or a ready-to-use intravesical gentamicin syringe. Compounding lets a licensed pharmacy prepare exactly the concentration, volume, and combination your urologist orders. As a 503A compounding pharmacy, Bayview Pharmacy prepares each order as a sterile preparation under USP <797> standards in an ISO 5 primary engineering control, and dispenses it in single-patient syringes labeled “For intravesical/bladder instillation only — NOT for injection.” Compounded preparations are not FDA-approved.
Clinical details for prescribers
Regulatory status. Gentamicin, heparin, lidocaine, and sodium bicarbonate are not controlled substances. DMSO 50% (RIMSO-50) is the only FDA-approved intravesical agent for interstitial cystitis, labeled for “symptomatic relief of patients with interstitial cystitis.” Intravesical gentamicin and heparin/lidocaine/bicarbonate combinations are entirely off-label, with no FDA-approved product in these combinations or in ready-to-use syringes. Compounded preparations are not FDA-approved.
Formulations & SIG. Gentamicin intravesical irrigation 0.48 mg/mL and 1.3 mg/mL (60 mL syringes) and 5.33 mg/mL (30 mL syringes); heparin 10,000 units / lidocaine 80 mg / sodium bicarbonate 1 mEq per 50 mL, dispensed as 100 mL. Representative SIGs: instill 60 mL via catheter or CIC nightly after the last void and retain until the next void, tapering per protocol; or instill 50 mL and retain 20–30 minutes weekly during a flare. One published gentamicin protocol runs daily × 10 days, alternate days × 4 weeks, weekly × 2 months, then stop. All prepared under USP <797> in an ISO 5 primary engineering control; beyond-use dating is assigned per USP <797> category and testing performed and is printed on the label.
Evidence & clinical points:
- AUA IC/BPS (2022) Statement 17: “DMSO, heparin, and/or lidocaine may be administered as intravesical treatments” — Option; Evidence Grade C (DMSO), C (heparin), B (lidocaine). Statement 24 recommends against intravesical BCG outside investigational settings (Standard, Grade B).
- The 2025 AUA/CUA/SUFU recurrent uncomplicated UTI in women guideline does not address intravesical gentamicin. Its non-antibiotic prophylaxis statements: cranberry (Moderate, Grade B), D-mannose (Moderate, Grade B, may not be effective), methenamine hippurate (Conditional, Grade C), increased water intake (Conditional, Grade C).
- Rutherford et al. systematic review: 6 studies, 166 patients; all reported reduced UTI frequency, 2 significantly; 86/133 (65%) on prophylaxis remained infection-free; serum gentamicin undetectable in 99%; creatinine rise in 2%. Level 2a evidence.
- IC/BPS instillation data: Nickel et al. (n=102, randomized double-blind placebo-controlled), alkalinized lidocaine 200 mg daily × 5 days — 30% vs 10% improved at day 8 (P=0.012), attenuating to 24% vs 12% by day 15. Parsons (n=48), heparin 10,000 U three times weekly × 3 months — 56% good clinical remission, uncontrolled. Nomiya (n=32), 12 weekly instillations — 76% response at end of treatment but only 16% at 6 months. Short-term flare relief appears real; durable benefit is unproven and most data are open-label.
- Systemic gentamicin absorption is low with an intact urothelium but increases with mucosal disruption, augmentation cystoplasty or bowel segments, hematuria, recent instrumentation, or renal impairment — obtain serum gentamicin levels and monitor renal function in these patients. Avoid with aminoglycoside hypersensitivity, prior aminoglycoside ototoxicity, acute pyelonephritis (requires systemic therapy), or inability to catheterize. Watch for emergent local resistance and candiduria.
- Lidocaine systemic absorption rises with an inflamed or denuded urothelium; cap total dose, avoid stacking with other lidocaine products, and use caution with hepatic impairment and class I antiarrhythmics. Heparin risk is local and largely theoretical — consider active hematuria and prior HIT.
- Before instilling: confirm the IC/BPS diagnosis and exclude infection, malignancy, and stones. For gentamicin: pretreatment urine culture with susceptibilities, periodic culture to detect emerging resistance, serum creatinine at baseline and periodically, and gentamicin levels in augmented bladders or renal impairment.
- Track response with validated tools: O'Leary-Sant ICSI/ICPI, VAS pain scores, and a voiding diary; UTI frequency counts for gentamicin prophylaxis.
Ordering: e-prescribe to Bayview Pharmacy, 3844 Post Rd, Warwick, RI 02886 (NCPDP 4106882), or fax 401-284-4506. Licensed in RI, MA, CT, NJ, NH, and FL. Background: AUA IC/BPS Guideline (2022); Rutherford et al., Journal of Clinical Urology.
These are prescription compounded medications and are not FDA-approved. This information is educational and is not medical advice. Your urologist determines whether instillation therapy is appropriate and sets the preparation, dose, dwell time, and schedule. Bayview Pharmacy does not provide consultations or determine appropriateness, and a valid prescription is required.
