Pethidine Paracetamol

Opioids such as diamorphine, pethidine, and pentazocine strongly inhibit gastric emptying and greatly reduce the absorption rate of paracetamol. Codeine, however, has no significant effect on paracetamol absorption. Morphine and diamorphine have been shown to reduce the absorption of antiarrhyth-mics such as mexiletine in patients with myocardial infarction. 

Aspirin, paracetamol, and hydrocortisone are used to control febrile reactions of amphotericin. Patients with a history of adverse effects with amphotericin should be prophylactically treated with antipyretics and hydrocortisone. Antiemetics and pethidine also are used for the treatment of adverse effects of amphotericin. With sodium supplements and hydration therapy, damage to the kidney can be reduced. If conventional amphotericin is not well tolerated by the patient, colloidal carriers can be used as alternative options. Administration of amphotericin with a nephrotoxic drug, such as cyclosporin, may further increase toxicity. Diuretics and anticancer drugs should be avoided with amphotericin. 

This chapter concentrates on some drug choices in acute rather than chronic pain, but the same principles can be used to determine the appropriateness of other types of analgesic. The drugs considered in this section are paracetamol, non-steroidal anti-inflammatories (NSAIDs specifically diclofenac, ibuprofen, indometacin, naproxen, sulindac and tenoxicam) and opioids (codeine, dihydrocodeine, morphine, pethidine and tramadol). Unless otherwise stated, all pharmacokinetic data originate from standard reference sources [1-5] and apply to adults only. 

Diamorphine, morphine, oxycodone, pentazocine and pethidine delay gastric emptying so that the rate of absorption of paracetamol given orally is reduced. There is no pharmacokinetic interaction between codeine and paracetamol, but the combination may not always result in increased analgesia. 

In 8 healthy subjects the absorption of a single 20-mg/kg oral dose of paracetamol solution given 30 minutes after an intramuscular injection of either pethidine 150 mg or diamorphine 10 mg was markedly delayed and reduced. Peak plasma paracetamol levels were reduced by 31% and 74%, respectively, and delayed from 22 minutes to 114 minutes and 142 minutes, respectively. This interaction was also observed, by the same study group, in women in labour who had been given paracetamol tablets after receiving pethidine, diamorphine or pentazocine. ... 

Some changes in nomenclature follow from WHO s Intematioml Nonproprietaiy Names for Pharmaceutical Substances (1982). Adrenaline, oestrone, and sulphanila-mide have become epinephrine, estrone, and sulfanilamide, respectively. American readers will note the following changes in that list (the internationally agreed name is in parentheses) acetaminophen (paracetamol), albuterol (salbutamol), chlorpheniramine (chlorphenamine), dibucaine (cinchocaine), isoproterenol (isoprenaline), mechlorethamine (chlormethine), melphalan (sarcolysin), meperidine (pethidine), metaproterenol (orciprenaline), pyril-amine (mepyramine), methimazole (thiamazole) and rifampin (rifampicin). 

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