It is a methyl ester of morphine and less potent than analgesic than morphine.It is widely used as antitussive agents.Codeine depresses the cough center even in small doses.Codeine use has lesser chances of addiction and tolerance is uncommon.
Itabsorbs well when given orally compared to morphine. Duration of action is 4-6 hrs. Antitussive dosage is 10 – 30 mg. Codeine is also available in combination with paracetamal for analgesia. (CODPLUS: Codeine 30 mg + Paracetamol 500 mg)
Is a recently developed synthetic codeine analog. It acts via opioid receptors in CNS to produce analgesia. It also inhibits the reuptake of nor adrenaline and serotonin. It is indicated to moderate, severe, chronic pain and in painful diagnostic procedures and in surgery.
It is also known as Meperidine. Pethidine is 1/10th as potent as morphine. (100 mg of pethidine = 10 mg of morphine). Onset of action is more rapid and duration of action is very short. It produces corneal anesthesia.
Onset of action begins after 15 minutes when ingested orally. Absorption is erratic after IM injection. Pethidine crosses placental barrier. Pethidine toxixity differs from morphine toxicity, it produces CNS excitation, which is characterized by tremors, muscle twitches and seizures.
A synthetic opioid, has actions similar to morphine. Its outstanding features are2. Effective analgesic3. Effective by oral route4. Its long duration of action effectively suppresses withdrawal symptoms in opioid addicts.5. Used as substitution therapy for treating opioid dependence.
1 mg oral methadone are given for every 4 mg morphine.Its pharmacology are similar to that of morphine.Used as an anesthetic agent and for treating opioid dependence.
An opioid antagonist is an receptor antagonist that acts on opioid receptors. Commonly used opioid agonist are III.Naloxone IV.Naltrexone V.Pentazocine
Naloxone is a structural analog for morphine. It have high affinity to mu receptor and low affinity towatds delta and kappa sites. Naloxone is a drug of choice for treating morphine overdose. Used in reversing neonatal asphyxia due to opioid use in labour ward.
It is a pure antagonist and chemically related to Naloxone. It is more potent than Naloxone due to its longer duration of action. Used as a maintainence drug in morphine over dosage. Effective when administered orally. Alcohol craving is also reduced by Naltrexone.