This is a Quora question I was asked. My answer is as follows.
I am not aware of any specific product distributor to the pharmacy channel. The channel has largely consolidated into Walgreens and CVS, or pharmacy departments within major retailers.
Many distributors do not do actual sales for you, so in my opinion, it is not really worth using them unless the retailer specifically requests it. You still have to do your own sales. As a result, it is better to sell directly to and ship to the pharmacy retailers.
If you do find any independents you want to sell to, contact them and ask them if they work with any distributors.
For more about how to setup a relationship with a distributor, please see this Quora question that I answered.