50mg of ketotifen? the daily dose of keto is 1-2mg per day.
Looks like he said Benadryl. In that case, each cap is generally 25mg.
The ECA should not down regulate your B2 receptors at same degre than Albuterol or Clen do. In fact you can alternate two weeks of clen (or longer if you use ketotifen), and two weeks of EC stack. Take your keto while you arte on clen or Albuterol.
While Ephedrine will not downregulate B2 receptors as fast as Clen or Albut., it will still down-regulate them. Most of the results you see during prolonged cycles of ECA (12 weeks cycles) are a result of B3 stimulation, as they do not seem to downregulate.
Alternating ECA w/albuterol or clen is pointless, and actually probably counter-productive. Clen will generally fry your B2 receptors by 2 weeks, and then using ECA will not allow them to recover. By the time you go back to the Clen, your B2's are already fried, and the B2's are clen's mode of action.
Alternating clen or albuterol with a non-beta receptor agonist such as yohimbine is probably a better option.