Tried to push it on you, or prescribed it and you filled it? Often doctors will prescribe the new drug to help patients save money: the insurance company doesn't yet realize it's the same as the cheap generic, and will pay the full cost for you because it's the only drug in its class available. (Buying the over-the-counter drug, you have to pay 100% of its cost from your taxable income, instead of paying $7 from your tax-free income. Then again, given a year's supply of generic Zyrtec is like $20 on Amazon... you'd have to have a pretty high tax rate for that to make sense.)
Obviously, insurers have wised up to this scheme with the "new" allergy drugs, but in other cases, it can be helpful.
In some cases it makes sense for sure. I'm guessing that or something like that is probably why Lucentis is also a blockbuster drug. If the price makes sense then what's the point in thinking any more about it? I would just go with the most affordable option.
In my case, he prescribed it and I asked for an alternative after a small case of sticker shock at the pharmacy (and the pharmacist was the one that mentioned it's practically Zyrtec). The next visit he dumped a couple months worth of samples into my lap and told me I should just stick with it and pay for it because it's worth it, so have some manufacturer coupons - you know, the same doctor that prescribed Zyrtec to me before Zyrtec was OTC, hahahaha. I'm still assuming that he wasn't after a kickback as much as it was just sticking with anything that worked at all in the months that I had bronchitis and sinusitis at the same time (with existing allergies and asthma, it was a terrible hell). Except he kept telling me to give it a chance after all that was over. Then I changed insurance plans and he wasn't in network so that was that.
I think the most unfortunate thing is that pricing is pretty opaque. Outside of that and a couple other situations, my doctors have been really helpful in trying to find cheaper alternatives but they don't know what is cheaper other than having someone spend time with the pharmacist going down a list of alternatives. Another anecdote from helping my dad: I used to set aside 2 hours every time he got a new prescription from his ophthalmologist. There were eyedrops that were literally $5/bottle/month, and then there were eyedrops that retailed for over $500 for a fucking 10ml bottle ~1 month supply (I'm looking at you Alphagan P). Every insurance company and plan would be different so someone from the doctor's office had to call the pharmacy and dealing with this took a couple extra hours on my end. Sometimes some brand name would be drastically cheaper than the generic (this happened with Adderall with my old insurance plan). Sometimes the price changed for no discernible reason (not even like anything to do with deductibles). It drove me nuts.
This kind of ridiculousness is yet another reason to be glad of the UK health system: flat charge of ~$10 for filling any prescription, and even that can be waived for large categories of people who have trouble affording it.
Having said that, certain categories of extremely expensive drug aren't available on the NHS; until recently Herceptin was the most prominent example of this.
Obviously, insurers have wised up to this scheme with the "new" allergy drugs, but in other cases, it can be helpful.