If you have the time, I would be very very interested and grateful to hear your take on Veltassa and your own experience with it, (if you have had any) now that it has arrived on the market. Data does seem to indicate that it has a better safety profile than it's counterpart ZS-9 in a number of ways. ZS-9's heavy sodium load has been shown to be capable of leading to some considerable adverse effects, including most prominently the danger of hypertension in CKD patients. Further, the sodium component, alongside the heavy fluid intake required (240ml water per dose) in patients already with potential fluid overload issues sounds worrisome. Besides these potentially mortal effects, observed peripheral edema is concomitant of the issues noted above and I was idly wondering how much patient comfort comes into consideration when choosing between courses of treatment.
The issue of hypertension is perhaps the most striking when I compare both treatment's safety profiles. From what I have read, Veltassa may even provide a lowering of a patient's blood pressure. I could not find data on this, but came across a podcast involving Relypsa's CMO who indicated their findings on this will be published around the start of May. Very exciting stuff. This would be in stark contrast to ZS-9's long-term study (ZS005) which - though still underway - can be used to project a hypertension level of around 15% of prospective patients using interim data. This higher BP can be related to the impact of the sodium load being released and then absorbed by the body I would initially assume. Recent studies also indicate sodium's detrimental effect on the progression of those with CKD, besides the aforementioned issues with patient's blood pressure. For reference, every 5g dose of ZS-9 contains 400mg of salt, upto a maximum of 1200mg of salt for the maximum 15g dose. Perhaps What's most striking about this however is that ZS Pharma's hypertension threshold was 180/105mmHg in this trial! Surely if it were lower we would of seen many more cases emerge? Also, as far as I can tell, patients did not received renin-angiotension-aldosterone system inhibitors, which was specified as being included in Veltassa's Phase 3 trial. Given their importance this worries me even more if they were not used.
Having said all of this, ZS-9 does seem to have a more rapid onset of action in correcting levels of potassium. This seems the only saving grace that I can see for this drug in comparison to Veltassa, but I am no professional and would welcome knowledge and corrections to the contrary!
Sooo... taking into consideration all of this - as well as your own intimate knowledge with treating patients with CKD - what is your own perception and professional opinion on ZS-9's sodium issues and its general safety profile in comparison to Veltassa? Do you perhaps know what the wider perception of both drugs in the nephrologist field is, and how they would be used in a medical setting? Could you imagine ZS-9 still having a place in the clinic for acute cases - i.e, emergency cases where a rapid onset of action is required of which Veltassa could not provide? If there is anything else you'd like to talk about in respect to these two treatments or CKD please feel free! I would find anything you could tell me on the subject more interesting than I probably should... haha.
Some relevant information on both the ZS004 trial study and ZS005 trial study, respectively:
http://sciencedaily.com/releases/2015/09/150918080614.htm High dietary sodium, potassium may worsen chronic kidney disease
Thanks a lot Jordan, any professional opinion and insight you can provide on this matter would be greatly appreciated