Fentanyl physical effects

Generally speaking, fentanyl acts on the central nervous system and the gastrointestinal tract. Because of this, most of the effects of the drug are physical. It also causes many of the same effects as heroin, including euphoria and drowsiness. However, some research shows that the effects of heroin are more euphoric, and fentanyl is more analgesic. 

Patients taking naltrexone (trade name Trexan) must tell their health care professional because the two drugs will cancel any effects that the other has. Some other medications that reduce the effects of fentanyl are buprenorphine, dezocine, nalbuphine, and pentazoncine. These medications also can cause side effects in people who have become physically dependent on fentanyl. 

Roy SD, Flyim GL (1989) SolubUity behavior of narcotic analgesics in aqueous media solubilities and dissociation constants of morphine, fentanyl and sufentanil. Pharm Res 6(2) 147-151 Rubinstein M, Colby RH (2003) Polymer physics. Oxford University Press, New York Rumondor ACF, Taylor LS (2010) Effect of polymer hygroscopicity on the phase behavior of amorphous solid dispersions in the presence of moisture. Mol Pharm 7(2) 477-490 Rumondor ACF, Marsac PJ, Stanford LA, Taylor LS (2009) Phase behavior of poly(vinylpyrrolidone) containing amorphous solid dispersions in the presence of moisture. Mol Pharm 6(5) 1492-1505... 

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