Ok a couple things, as Methacodone pointed out above.
FDA (inspects & approves for market), Pure Food & Drug Act (Mandates all medications((food & drink too but nevermind that)) list all ingredients, dosage, etc...), and last but definitely not least, the United States Pharmacopia(U.S.P.)( Massive database containing all medications OTC, Rx, & otherwise).
The last place any American should knowingly buy drugs from is IRAN ffs!!
Iran leads the world, it's #1 in State-Sponsored Terrorism. Thank you Iranians, but I can survive a few days without dope, LOL!
Good people for the most part, but politics aside, I seriously doubt their Pharmaceutical Manufacturers are quite up to U.S./U.K. Specifications & Qualifications. We're talking 3rd world, developing contries, their infrascruture isn't even close to ours, nevermind their rules & regulations to protect consumers. The latter is probably non-existent, or as good as non-existent.
P.S. Quality Control.....name of the game buddy!