Dextropropoxyphene Tricyclic antidepressants

There are concerns that citalopram may be less safe in acute overdose than other SSRIs (SEDA-21,12). Among all fatal poisonings in one forensic district of Sweden, citalopram was the fourth most commonly used drug (22 of 358 cases) (29). However, when correction was made for prescription rate, citalopram was less toxic than amitriptyline, dextropropoxyphene, or nitrazepam. This study has confirmed that citalopram is less toxic than tricyclic antidepressants such as amitriptyline. However, whether it is more toxic than other SSRIs is still uncertain. 

Paracetamol plus dextropropoxyphene, the combination known as co-proxamol, is available as a prescription-only analgesic in many countries. Self-poisoning can be lethal, as respiratory depression can occur from an excessive dose of dextropropoxyphene. In England and Wales, co-proxamol alone accounts for 5% of all suicides, and overdose is more likely to result in death than overdose with paracetamol alone or tricyclic antidepressants (81). Furthermore, although it is often prescribed, it is no more effective than paracetamol for short-term relief of pain. It should not be prescribed without good... 

The manufacturer states that nefopam should not be given to patients taking non-selective MAOIs and caution should be used in those taking tricyclic antidepressants, antimuscarinics and sym-pathomimetics. The intensity and incidence of adverse effects are somewhat increased when nefopam is given with codeine, pentazocine or dextropropoxyphene (propoxyphene), and the CNS depressant effect of dihydrocodeine may have contributed to a fatal overdose with nefopam. However, a morphine-sparing effect has been reported. Nefopam may also have a synergistic analgesic effect with ketoprofen. 

The CNS depressant effects of opioids and the tricyclic antidepressants are expected to be additive. The reasons for the increased morphine levels and analgesic effects that occur with some tricyclics are not understood. The increased analgesia may be due not only to the increased serum levels of morphine, but possibly also to some alteration in the way the morphine affects its receptors. Dextropropoxyphene probably inhibits liver metabolism of some tricyclic antidepressants by inhibiting the activity of the cytochrome P450 isoenzyme CYP2D6, and as a result the serum levels of the tricyclic antidepressants rise. It is suggested that the methadone may possibly inhibit the hydroxylation of the desipramine, thereby raising its levels. ... 

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