This drug was developed in the same time frame as Byetta and is similar in concept. But it's side effect profile was more troubling, hence the delay. It's being released with a warning that it might produce thyroid cancers, though this supposedly is mostly a problem in rodents. Even so, the fact that the thyroid cancer issue can't be completely dismissed would make a reasonable person ask, "What does this drug offer that makes it worth taking on even a tiny bit more risk than is found with Byetta?"
You can read the full European prescribing information for Victoza here:
Victoza Prescribing Information.
As far as I can see the only possible benefit to taking Victoza over Byetta is that it requires a once a day shot, rather than the twice a day schedule of Byetta. That said, it appears to produce less blood sugar control than Byetta does--when Byetta works, which isn't always--and reading between the lines, it doesn't look to me as Victoza has as good an impact on weight as Byetta does.
When looking at statistics for both these drugs, keep in mind that other research has found that Byetta is a drug that is worthless for two thirds of of those who take it and magic for the other third. This means that the averages published in Prescribing Information documents aren't a good guide to its effect.
If out of ten people taking a drug, three people drop 30 lbs each and the other seven gain 3 pounds each, the average weight loss is 7 lbs, but that statistic fails to reflect reality in any meaningful way.
The same is true with blood sugar control, as some people respond dramatically to Byetta and others who take it actually see their blood sugar go up.
With this in mind, it's hard to compare Byetta to Victoza based on published statistics. The average A1c drop reported when patients take Victoza and Metformin is 1%, which is really no better than the drop achieved taking Metformin alone.
Most tellingly the Victoza prescribing information presents no statistic for the impact of Victoza on blood sugar when it is not being given in combination with another blood sugar lowering drug.
This suggests very strongly that on average the drug has no impact on A1c, but because it might have a stronger impact on a subset, as Byetta does, it can't be dismissed.
My take on this drug is this: There is little reason to take it. The longer duration means that if you get the serious gastrointestinal reaction that GLP-1 analogs can cause, it's going to take a lot longer to wash out of your body. If you aren't going to respond to Byetta, it isn't likely you'll respond to this drug either, as non-response suggests that fiddling with GLP-1 isn't going to help you. The impact is less than Byetta and the side effects more troubling, especially since it is a new drug and hasn't been prescribed to a large group of patients as Byetta has.
To me the most worrisome side effect is this. As the prescribing information reports,
The overall rates of thyroid adverse events in all intermediate and long-term trials are 33.5 [Victoza], 30.0 [Placebo] and 21.7 events per 1000 subject years of exposure for total liraglutide, placebo and total comparators; 5.4 [Victoza], 2.1 [Placebo] and 0.8 events, respectively concern serious thyroid adverse events. In liraglutide-treated patients, thyroid neoplasms, increased blood calcitonin and goiters are the most frequently thyroid adverse events and were reported in 0.5%, 1% and 0.8% of patients respectively.Bottom Line: Stick with Byetta and keep an eye on longer-term research findings about this drug. There's no reason to take it that trumps the mediocre performance and possible thyroid risk.