Rifampin for Central Serous Chorioretinopathy

30 08 2010

The first full day of the American Society of Retina Specialists Annual Meeting has just ended here in Vancouver. It’s been a productive meeting so far, with a few clinical pearls that will change the way I practice. Yesterday’s case conference session had a memorable patient presented by Kirk Packo’s group in Chicago that will change the way I approach central serous retinopathy (CSR).

They presented a patient who had widespread chorioretinal lesions and a serous macular detachment. The thinking was that it could be due either to tuberculosis or to chronic CSR. The patient was placed on standard multi-drug therapy for tuberculosis and while on the therapy, the macular edema resolved. However, when the drugs were stopped, the fluid recurred. The patient was placed again on the TB drugs, the fluid again resolved, and when the drugs were stopped, the fluid again re-accumulated. At this point, they began to consider that the patient may not have TB, but may rather have chronic CSR and that one of the TB medications was having a positive independent effect on the serous retinopathy.

The reviewed the list of TB drugs and realized that rifampin has the ability to decrease endogenous steroid production, and that perhaps this was resulting in resolution of the patients serous retinopathy. They gave the patient a trial of rifampin alone (600 mg per day) and voila, the fluid resolved again.

Since that time, they had used rifampin in several other patients with CSR and have seen resolution of the fluid within 1-4 weeks. The case presentation doesn’t prove anything, and further study is required, but it does raise the possibility that rifampin may help CSR, particularly chronic cases, and I will now consider it as an option to offer select patients with central serous chorioretinopathy.

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Lucentis vs Avastin: Who will win the race?

9 08 2010

As we await the results of the NIH sponsored CATT trial, a head-to-head comparison of ranibizumab (Lucentis) and bevacizumab (Avastin), other smaller studies are trickling in, pointing to what many of us suspect from clinical experience — their efficacy is pretty much the same. Fong et al. published a study in the February issue of Ophthalmology (Intravitreal bevacizumab and renibizumab for age-related macular degeneration) which compared the results from 342 pateints treated with bevacizumab and 128 with ranibiumab. It was a non-randomized trial and the bevacizumab patients were younger. The study showed that both groups had fairly equal results at 12 months. About 23% of bevacizumab patients and 25% of ranibizumab patients had visual acuity of 20/40 or better. More patients with bevacizumab (27%) had improved vision compared to ranibizumab (20%). So, I think we can call it close to even, and remember that about 25% will have improvement of vision and the same percentage with get to 20/40 or better.

The one point that stood out was that in a year, the bevacizumab patients needed about 4 injections, whereas the ranibizumab patients needed 6 injections. This is in keeping with the thought that bevacizumab, being a larger molecule, stays around longer and has a longer duration of action.

Which brings us to the road ahead. The fact that the CATT study has not been stopped, points to the fact that bevacizumab is likely not either significantly less effective or more dangerous than its $2000 per dose cousin, ranibizumab. Both drugs are made by Genentech, bevacizumab being the off-label one. It’s tough for a company to have two of its drugs competing against one another, especially if the off-label one wins or comes close to being even. I believe that Genentech’s approach in the coming years will be to make ranibizumab easier to use. The concern with both these drugs is the ongoing burden of repeat injections. We have a history of the development of sustained-release intraocular drugs in ophthalmology, and the next step is to get one of these drugs into a sustained release form to decrease the number of injections required. Genentech will develop ranibizumab in a sustained release form, leaving bevacizumab to be injected repeatedly. So the issue of equal efficacy will become moot.