See also Frequently Asked Questions About Heroin, Morphine, and the Opiates - Heroin/Morphine FAQ

There is a considerable tolerance present when middle to high doses of one opioid agonist are consumed before changing from one agonist to another. Changes are in this case not risky.

The change from pure opioid agonists to agonists/antagonists and to partial agonists always causes a more or less distinct withdrawal syndrome. The change in the opposite direction is on the other hand, possible without complaints.

The change from an opioid with a short half-life to an opioid with a longer half-life, due to different kinetics and cumulations, can lead to considerable under dosing in the first few days (see Abb.29 & 30).

By changing from one opioid to another or by distributing the daily dose over several combined administered opioids, the calculation base is always the measured day-before opioid dose in MDQ.

When consuming opioids twice a day, the daily dose is then (usually evenly) distributed over two doses and possible increases in dose that are possible from day to day are considered as well.

A maximum single dose is calculated out of the calculated total daily dose, when short-lasting opioids are consumed more than twice a day. In this case, one has a maximum possible daily dose worked out from the number of consumed single-doses (through prescription defined or left open).

Changing from peroral or injected methadone to short-lasting opioid agonists such as injected heroin, DAM-cigarettes and morphine is kinetically unproblematic.

The methadone consumed the day before is taken as the reference value. If the last methadone dose was consumed yesterday, the dose from the previous day in MDQ is converted (Methadone in mg = Methadone in MDQ, as the MDQ-Factor = 1) thus giving the daily dose of the new opioid. This daily dose of the new opioid needs to be converted from the unit MDQ into mg.

If no methadone has been consumed for a day or more, the dose needs to be linearly reduced by 20% per absent day due to the loss of tolerance (see chapter 16.4).

When changing from methadone to more than 2 heroin injections a day, half of the methadone dose, in MDQ, consumed on the day before can be injected as a single dose of heroin (examples 13 & 15).

Changing from methadone to two heroin injections a day follows analogue: the daily dose is simply distributed over 2 injections a day (example 14).

The contradictions in our equivalence table become clearly obvious when changing from methadone to heroin i.v.. The flash effect of injected heroin only starts to decrease at daily doses of 600 mg(see picture .27). When changing, the withdrawal-preventing effect of heroin is replaced, the flash-effect stays

On the other hand, intravenous injected heroin reaches the tolerance dose thus also the maximum effect in relation to analgesia and persistent euphoria (withdrawal-preventing opioid saturation) already at 300 mg/day(see picture 27). When changing from methadone to heroin i.v., the withdrawal-preventing opioid saturation as maximum-effect dose (tolerance dose), becomes more relevant. Our thoughts let us think that a MDQ-Factor of 3 for heroin i.v. seems sensible. In example 16, one is changing from methadone alone to a combination of methadone and 2 daily injections.

The change from methadone to morphinepentasulphate in retard form is shown in example 17. The daily dose is not increased when doing this change.

The change from methadone to DAM-cigarettes is not problematic when methadone has been consumed in small doses previously. As long as the methadone dose has remained under 50 mg, there can be an abrupt change without any transition. When doses of methadone of 50 mg or more have been consumed it is recommended that along with the DAM-cigarette full-dosing, that a parallel decreasing methadone dose is prescribed (pushing out methadone). Methadone has such a strong effect over 30mg that when taken in parallel, the effects of the DAM-cigarettes stay covered.

Giving more than 100 to 120 mg methadone per day is hardly justifiable except for this change, and can be problematic due to the increased possibilities to abuse the high dose.