release of the drug in the body whereas powder filled pellets generally cannot. The plastic spheres containing powder have micropores that open at varying PH levels, to maintain a mostly constant release during transit through the digestive tract. The spheres themselves, the outer shells, pass undigested in most patients. Other brands are thought to use ethylcellulose coatings to control drug release from pellets. Another use these style medications have is that they can be given via NG tube, the pellets being very small. This makes them one of the only extended release oral medications that can be given by feeding tube. Opioid replacement therapy According to a Cochrane review in 2013, extended-release morphine as an opioid replacement therapy for people with heroin addiction or dependence confers a possible reduction of opioid use and with fewer depressive symptoms but overall more adverse effects when compared to other forms of long-acting opioids. The length of time in treatment was not found to be significantly different. References External links Advanced consumer information: morphine sulfate Consumer Medicine Information (Australia) Analgesics Opiates Sulfates Pfizer brands