Mu and Kappa Receptors

Pure Opioid Agonist Examples

• Morphine

• Codeine

• Meperidine

Other morphine-like drugs

Pure Opioid Agonist Function

{Activates both receptors}

Mu: Agonist

Kappa: Agonist

Agonist-Antagonist Opioid Examples

• Pentazocine

• Nalbuphine

• Butorphanol

Agonist-Antagonist Opioid Function

Mu: Antagonist (NO)

Kappa: Agonist

Agonist-Antagonist Opioids Examples (partial antagonist)

Buprenorphine

Agonist-Antagonist Opioid Function (Partial Agonist)

Mu: Partial Agonist

Kappa: Antagonist (NO)

Pure Opioid Antagonist Examples

• Nalaxone

• Naltrexone

• Others

Pure Opioid Antagonist Function

Mu: Antagonist (NO)

Kappa: Antagonist (NO)

Mu Function

• Analgesia

• Resp depress

• Euphoria

• Sedation

• Decreased GI motility

• Physical dependence

Kappa Function

• Analgesia

• Sedation

• Decreased GI Motility

Laxatives

To counteract opioid constipation of Mu and Kappa receptors

Strong opioid antagonists

• Morphine

• Other strong opioids