Black box warning
Methadone has the following US FDA black box warning:
Risk of addiction and abuse
Potentially fatal respiratory depression
Lethal overdose in accidental ingestion
QT prolongation
Neonatal opioid withdrawal syndrome in children of pregnant women
CYP450 drug interactions
Risks when used with benzodiazepines and other CNS depressants, including alcohol. A certified opioid treatment program is required under federal law (42 CFR 8.12) when dispensing methadone for the treatment of opioid addiction or detoxification. Overdose
Most people who overdose on methadone show some of the following symptoms:

Miosis (constricted pupils)
Vomiting
Spasms of the stomach and intestines
Hypoventilation (breathing that is too slow/shallow)
Drowsiness, sleepiness, disorientation, sedation, unresponsiveness
Skin that is cool, clammy (damp), and pale
Blue fingernails and lips
Limp muscles, trouble staying awake, nausea
Unconsciousness and comaThe respiratory depression of an overdose can be treated with naloxone. Naloxone is preferred to the newer, longer-acting antagonist naltrexone. Despite methadones much longer duration of action compared to either heroin and other shorter-acting agonists and the need for repeat doses of the antagonist naloxone, it is still used for overdose therapy. As naltrexone has a longer half-life, it is more difficult to titrate. If too large a dose of the opioid antagonist is given to a dependent person, it will result in withdrawal symptoms (possibly severe). When using naloxone, the naloxone will be quickly eliminated and the withdrawal will be short-lived. Doses of naltrexone take longer to be eliminated from the persons system.
Idarubicin  or 4-demethoxydaunorubicin is an anthracycline antileukemic drug. It inserts itself into DNA and prevents DNA unwinding by interfering with the enzyme topoisomerase II. It is an analog of daunorubicin, but the absence of a methoxy group increases its fat solubility and cellular uptake. Similar to other anthracyclines, it also induces histone eviction from chromatin.It belongs to the family of drugs called antitumor antibiotics. It is currently combined with cytosine arabinoside as a first line treatment of acute myeloid leukemia. It is used for treatment of acute lymphoblastic leukemia and chronic myelogenous leukemia in blast crisis.It is distributed under the trade names Zavedos (UK) and Idamycin (USA). Side effects
Diarrhea, stomach cramps, nausea and vomiting are common among patients treated with idarubicin. References
External links
Idarubicin bound to proteins in the PDB