Oxycodone dosing

Divide this 24-hour oxycodone dose in half to obtain the twice-daily (every 12 hours) dose of CR tablets. 

Conversion from transdermal fentanyl to CR tablets Eighteen hours following the removal of the transdermal fentanyl patch, treatment with CR tablets can be initiated. Although there has been no systematic assessment of such conversion, a conservative oxycodone dose, approximately 10 mg every 12 hours of CR tablets, should be initially substituted for each fentanyl transdermal patch 25 mcg/h. Closely follow the patient for early titration as there is very limited clinical experience with this conversion. 

Figure 34-39 Metabolism of oxycodone and oxymorphone. Values in parentheses are percent of oxycodone dose excreted in urine. For oxymorphone dose, 1.9% is excreted as the parent drug, 44% as conjugates, and 3% as oxymorphoi.

A 60-year-old man who was taking rifampicin as well as oxycodone had 3 consecutive negative urine oxycodone screens in a 2-month period, which would normally suggest that he was not taking the oxycodone. However, oxycodone metabolites were found in his urine confirming compliance with his medication. An interaction between rifampicin and oxycodone was suspected and his oxycodone dose was increased to optimise his pain control. ... 

The effects of oxycodone, methadone, morphine, and tramadol on the QT interval and HERG channels involved have been studied in 100 patients taking opioids for chronic non-malignant pain [137 ]. Oxycodone and methadone caused prolongation of the QT interval, while morphine and tramadol did not oxycodone blocked HERG channels in vitro. An increase in oxycodone dose of 100 mg was associated with a 10 msec increase in QTc interval. 

The physician would like to convert him to a combination preparation of oxycodone and acetaminophen. What dosing regimen would you suggest ... 

Moderate 4-6/1 0 Add an opioid to the non-opioid for moderate pain regular scheduled dosing Acetaminophen 325 mg + codeine 60 mg every 4 hours Acetaminophen 325 mg + oxycodone 5 mg every 4 hours Consider step-up therapy if pain is not relieved by greater than or equal to 2 or more different drugs... 

Low-dose opioid analgesics (e.g., oxycodone) may be useful for patients who experience no relief with acetaminophen, NSAIDs, intraarticular injections, or topical therapy. 

Patients who are considered opioid-tolerant are those who have been taking, for a week or longer, morphine 60 mg/day or more, or oral oxycodone 30 mg/day or more, or oral hydromorphone 8 mg/day or more, or an equianalgesic dose of another opioid. 

Oxycodone CR tablets are to be swallowed whole and are not to be broken, chewed, or crushed. Taking broken, chewed, or crushed oxycodone CR tablets leads to rapid release and absorption of a potentially fatal dose of oxycodone. 

Patients currentiy on opioid therapy If a patient has been receiving opioid-containing medications prior to taking IR tablets, the potency of the prior opioid relative to oxycodone should be factored into the selection of the total daily dose of oxycodone. 

Using standard conversion ratio estimates (see table below), multiply the mg per day of the previous opioids by the appropriate multiplication factors to obtain the equivalent total daily dose of oral oxycodone. 

Multiplication Factors for Converting the Daily Dose of Prior Opioids to the Daily Dose of Oral Oxycodone- ... 

To be used only for conversion to oral oxycodone. For patients receiving high-dose parenteral opioids, a more conservative conversion is warranted. For example, for high-dose parenteral morphine, use 1.5 instead of 3 as a ... 

If signs of excessive opioid-related adverse experiences are observed, the next dose may be reduced. If this adjustment leads to inadequate analgesia, a supplemental dose of IR oxycodone may be given. Alternatively, nonopioid analgesic adjuvants may be employed. Make dose adjustments to obtain an appropriate balance between pain relief and opioid-related adverse experiences. 

Renal/Hepatic function impairment Renal and hepatic dysfunction may cause a prolonged duration and cumulative effect smaller doses may be necessary. Meperidine In patients with renal dysfunction, normeperidine (an active metabolite of meperidine) may accumulate, resulting in increased CNS adverse reactions. Pregnancy Category C, Category B, (oxycodone). 

Oxycodone/Lorazepam/Ethanol Multiple oral doses of pregabalin were coadministered with oxycodone, lorazepam, or ethanol. Although no pharmacokinetic interactions were seen, additive effects on cognitive and gross motor functioning were seen when pregabalin was coadministered with those drugs. 

Depending on the type, opioids can be injected, smoked, snorted, or taken orally. Smoking heroin is termed chasing the dragon. ControIIed-release oral tablets of morphine (MS-Contin ) or of oxycodone (OxyContin ) should never be crushed or chewed, as the entire dose of opioid released at once may be toxic. 

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. 

Most opioid analgesics are well absorbed when given by subcutaneous, intramuscular, and oral routes. However, because of the first-pass effect, the oral dose of the opioid (eg, morphine) may need to be much higher than the parenteral dose to elicit a therapeutic effect. Considerable interpatient variability exists in first-pass opioid metabolism, making prediction of an effective oral dose difficult. Certain analgesics such as codeine and oxycodone are effective orally because they have... 

Codeine,oxycodone, dihydrocodeine, and hydrocodone are all somewhat less efficacious than morphine (they are partial agonists) or have adverse effects that limit the maximum tolerated dose when one attempts to achieve analgesia comparable to that of morphine. 

Oral 5 mg oxycodone plus 325 or 500 mg acetaminophen tablets. Note High-dose acetaminophen has potential for hepatic toxicity with repeated use. 

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. 

The success of prolonged-release morphine prompted the development of prolonged-release formulations for other opioids, for example the matrix made of hydrophobic and hydrophilic matrix formers, for example on hydrocodeine (DHC retard with cetostearyl alcohol and hydroxyethyl-cellulose), oxycodone (oxygesic with stearyl alcohol and polyacrylate) and tramadol (tramundin with cetostearyl alcohol and ethylcellulose). By virtue of the oblong shape of hydrocodeine and tramadol tablets the prolonged-release tablets can be divided, whereby compared with whole tablets release from the divided tablets is slightly accelerated. The difference with these forms is that with increasing dose the release slows down. 

---