West Marin Pharmacy is facing yet another challenge. Cigna Healthcare, a company that insures as much as 10 percent of the pharmacy’s customer base, stopped covering medication expenses at the pharmacy in May, due to a probation the pharmacy has been on since 2020 after it was found in violation of several safety standards. The decision came at the behest of the insurance company’s pharmacy benefit manager, Express Scripts, and impacts more than 100 customers…