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on an as-required basis but not within 3 hours of the last fixed dose. The total dose required over a 24-hour period is calculated after 5–6 days, divided and given as a two or three times daily regimen and this avoids the build-up of methadone within the body (Morley and Makin 1998). Titration is recommended within a hospital setting to ensure accurate administration. This can be difficult for patients because they have to experience pain before they are administered a dose of methadone in the titration period.

Methadone can be a cheap, effective alternative to morphine if titration is supervised by the specialist pain or palliative care team (Gardner-Nix 1996).

It is particularly useful in patients with renal failure. Morphine is excreted via the kidneys and if renal failure occurs, this may lead to the patient experiencing severe drowsiness as a result of accumulation of morphine metabolites (Gannon 1997). Methadone is lipid soluble and is metabolized mainly in the liver. About half of the drug and its metabolites are excreted by the intestines and half by the kidneys.

Oxycodone

Oxycodone is available as an immediate- or modified-release preparation and titration should occur in the same way as morphine. Oxycodone is a useful opioid as an alternative to morphine (Riley 2006). It has similar properties to morphine and can be administered orally, rectally and parenterally. Oxycodone has similar side-effects and it is usually given 4–6 hourly. Oxycodone has an analgesic potency of 1.5–2.0 times higher than morphine. It has similar side-effects to morphine, although oxycodone has been found to cause less nausea (Heiskanen and Kalso 1997) and significantly less itchiness (Mucci-LoRusso et al. 1998).

Targinact

This drug is a combination of modified-release oxycodone and naloxone. The aim of the combination of these medications is to prevent the potential negative effects on bowel function. It is suggested that approximately 97% of the naloxone is eliminated by first-pass metabolism in the healthy liver, preventing it from significantly affecting analgesic effects (Vondrackova et al. 2008).

Diamorphine

Diamorphine is used parenterally in a syringe driver pump for the control of moderate to severe pain when patients are unable to take the oral form of morphine. It is calculated by dividing the total daily dose of oral morphine by three. Breakthrough doses are calculated by dividing the 24-hour dose of diamorphine by six and administering on an as-required basis (Hanks et al. 2004). A recent problem with the supply of diamorphine nationally has resulted in centres using morphine sulphate or an alternative opioid as a substitute.

Alfentanil

Alfentanil is also a useful alternative to diamorphine and is used for those patients who have renal impairment. The onset of action is rapid owing to a more rapid blood–brain equilibration. It is 10 times more potent than diamorphine (i.e. diamorphine 10 mg = alfentanil 1 mg). The breakthrough dose can be calculated as one-tenth of the 24-hour dose as opposed to the usual one-sixth. For example, 1 mg of alfentanil over 24 hours will require a breakthrough dose of alfentanil 0.1 mg.

Buprenorphine

Buprenorphine is an alternative strong opioid available in a patch form. The patch has similar advantages to fentanyl but does not contain a reservoir of the drug. Instead it is contained in a matrix form with effective levels of the drug being reached within 24 hours. Titration is recommended with an alternative opioid initially and then transfer to the patch when stable requirements have been reached. A lower dose patch (Butrans) is available in strengths of 5, 10 and 20 μg/h that should be worn continuously by the patient for 7 days. The higher dose patch (Transtec) of 35, 52.5 and 70 μg/h is now licensed to be used up to 96 hours or twice weekly for patient convenience. Conversion is based on the chart supplied by the pharmaceutical company which demonstrates equivalent doses. Buprenorphine is also available as a sublingual tablet, which is titrated from 200 to 800 μg 6-hourly. Conversion