Penile Injectable Medications for ED. Injection therapy has been an efficacious treatment option for patients since it was introduced in 1983 (Brindley, 1986). Efficacy for this treatment option is as high as 87% to 93% (Linet & Ogring, 1996; Porst, Buvat, Meuleman, Michal, & Wagner, 1998).he same dose of generic compounded prostaglandin E1 is approximately $8 to $10 per injection from a compounding pharmacy. A 1 ml dose (which is actually a maximal dose) of trimix or quadmix costs about $12 to $15 per dose.