Pethidine Hydrochloride

Adults: Analgesia Adjust the dose of Pethidine Hydrochloride to the severity of the pain and how the patient responds. It also depends on the patient's profile, for example age, weight, sex and previous exposure to narcotics. The usual doses are 25 to 100 mg by IM (preferred) or S.C. injection every 3 to 4 hours, or 25 to 50 mg by slow IV injection every 3 to 4 hours. The usual dose by the IV route is 200 mg/day. Give intravenous injections very slowly, preferably as a diluted solution. For a continuous intravenous infusion, establish adequate analgesia before starting the infusion. The recommended initial intravenous infusion rate is 0.3 mg/kg/hr. Clinical experience suggests that patients with normal renal function who receive more than 1000 mg/24 hrs of pethidine are at particular risk of pethidine associated neurotoxicity (PAN). Patients receiving over 800 mg/24 hrs should usually be monitored for early signs of norpethidine toxicity. Obstetric Analgesia Give 50 to 100 mg by IM (preferred) or S.C. injection once the pain becomes regular. If necessary, repeat 3 to 4 times at intervals of one to three hours. The maximum is 4 doses in 24 hours. Anaesthesia Adjunct As premedication, give 50 to 100 mg intramuscularly (preferred) or subcutaneously, thirty to ninety minutes before anaesthesia. As an adjunct during anaesthesia, give it intravenously by repeated slow injection of fractional doses of a solution diluted to 10 mg per mL. The dose by this route should not exceed 25 to 50 mg. Titrate the dose to the patient's needs, depending on the premedication given, the type of anaesthesia, and the nature and duration of the surgical procedure. Patient-Controlled Analgesia With patient-controlled analgesia (PCA), the patient judges their own level of pain and so titrates the amount of pethidine they need for adequate pain control against sedation and other side effects. Establish adequate analgesia before starting PCA. The doses and time intervals are preset in a microprocessor-controlled infusion pump. When the patient feels pain, they press a button and a dose of pethidine is given intravenously. If the button is pressed before the preset time interval (the lockout interval) has passed, no extra drug is given. For adults, demand doses of 5 mg to a maximum of 20 mg pethidine have been given by PCA, with a lockout interval of 6 to 20 minutes. Some syringe pumps also deliver a background continuous infusion of pethidine at a basal rate along with the self-administered dose. Some PCA pumps let you preset a maximum dose over a defined period, to avoid overdosage. Set the demand dose and lockout interval according to the patient's analgesic requirements. Patients on a background infusion should generally get a smaller demand dose than equivalent patients on a demand dose only. Clinical experience suggests that patients with normal renal function who receive more than 1000 mg/24hrs of pethidine are at particular risk of developing pethidine associated neurotoxicity (PAN). Patients receiving over 800 mg/24hrs should usually be monitored for early signs of norpethidine toxicity. Pethidine-associated neurotoxicity is dose related, so pethidine should not be used for longer than 24 to 36 hours. Paediatric Dose For analgesia, give 0.5 to 2 mg per kg of body weight intramuscularly (preferred) or subcutaneously, not to exceed 100 mg, every three to four hours as needed. For preoperative use, give 1 to 2 mg per kg of body weight intramuscularly (preferred) or subcutaneously, not to exceed 100 mg, thirty to ninety minutes before anaesthesia. Neonates: pethidine is excreted and metabolised more slowly in the neonate than in adults. Safety has not been established in neonates, and because there is no data, no dosage regimen can be recommended.