Oxycodone Paracetamol

An example of a simple oxidatiim reaction is the craiver-sion of Fe " into Fe. Examples of active substances that are prone to oxidation are acetylcystein, adrenaline, apomorphine, clioquinol, dithranol, dobutamine, ergotamine, hydroquinone, isoniazid, mesalazine, naloxone, neomycin, oxycodone, paracetamol, peptides, salbutamol, phenothiazine derivatives (promazine, promethazine, chlorpromazine), phenylephrine, physostigmine, tetracycline, tretinoin, the vitamins A and D, and the excipients flavouring agents, fragrances and unsaturated fats (vegetable oils, suppository bases). 

Codeine, one of the principal alkaloids of opium, has an analgesic efficacy much lower than other opioids, due to an extremely low affinity for opioid receptors. It is approximately one-sixth as potent as morphine. It has a low abuse potential. In contrast to other opioids, with the exception of oxycodone, codeine is relatively more effective when administered orally than parenterally. This is due to methylation at the C3 site on the phenyl ring (Figure 7.3), which may protect it from conjugating enzymes. It is used in the management of mild-to-moderate pain, often in combination with non-opioid analgesics, such as aspirin or paracetamol. It is valuable as an antitussive and for the treatment of diarrhoea. Side effects are uncommon and respiratory depression, even with large doses, is seldom a problem. 

Dosages and routes of administration Oxycodone is given by mouth in single doses of 5-10 mg or as controlled release preparations with doses of 40 mg (Cairns, 2001). Rectal administration is also possible. Oral formulations often contain combinations with paracetamol or acetylsalicylic acid. 

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. 

A crossover study in 10 healthy subjects investigated the effect of oxycodone 500 micrograms/kg on the absorption kinetics of a simulated paracetamol overdose (5g). The maximum serum paracetamol level was reduced by 40%, the time to maximum level was increased by 68%, and the AUCq 8 was 27% lower, when compared with paracetamol alone. ... 

Including 11 cases and 6 controls who reported taking a preparation of paracetamol in combination vmh an opioid, mostly codeine and oxycodone There are also cases reported with dextropropoxyphene/paracetamol. 

Oxycodone (trade names in Germany Oxygesic , Eukodal , in the USA Oxi-Contin ) is also used in combination with paracetamol or aspirin for the control of severe pain. It is obtained from thebeine by oxidation with hydrogen peroxide and hydrogenation of the vinylogous double bond. 

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