An anti-diarrheal drug is any
medicationwhich provides symptomatic relief for diarrhea.
Electrolytesolutions are used to replace lost fluids and salts in acute cases.
Bulking agents like methylcellulose, guar gumor plant fibre ( bran, sterculia, ispaghul, etc.) are used for diarrhea in functional bowel disease and to control ileostomyoutput.
Absorbents absorb toxic substances that cause infective diarrhea, methylcellulose is an absorbent as well.
Opioids classical use besides pain relief is use as an anti-diarrhea drug. Opioids have agonistactions on the intestinal opioid receptors, which when activated cause constipation, drugs such as morphineor codeinecan be used to relief of diarrhea this way. A notable opioid for the purpose of relief of diarrhea is Loperamidewhich only is an agonist of the μ opioid receptors in the large intestine and does not have opioid affects in the central nervous system as it doesn't cross the blood brain barrier in significant amounts. This enables loperamide it to be used to the same benefit as other opioid drugs but without the CNS side effects or potential for abuse.
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