RIMA - Reversible Inhibitor of MonoAmine oxidase (type A)
Also referred to as a reversible MonoAmine Oxidase Inhibitor (rMAOI)
Please note: Dosage equivalents are provided for certain drugs below and are denoted as unit equivalents, i.e. one unit of drug x is roughly the equivalent as one unit of drug y, where the dosage equal to one unit varies.
RIMA antidepressants share much of their properties with MAOI antidepressants, the differences being reversibility and selectivity.
Whereas MAOI drugs permanently bind with monoamine oxidase enzymes (thereby preventing them from breaking down monoamine neurotransmitters, notably serotonin, noradrenaline and dopamine), RIMA drugs bind with the enzymes in a reversible manner and can detach, thereby reactivating the enzyme.
Monoamine oxidase enzymes are split into two isoforms, MAO-A and MAO-B. MAO-A chiefly breaks down serotonin, melatonin, adrenaline and noradrenaline, whilst MAO-B breaks down phenylethylamine and trace amines; dopamine seems to be pretty evenly spread over the two of them. RIMA antidepressants preferably inhibit MAO-A rather than MAO-B; moclobemide, for instance, at a dose of 300mg roughly inhibits 80% of MAO-A enzymes and 25% of MAO-B enzymes.
In terms of effectiveness, RIMA antidepressants are weaker than typical or irreversible MAOIs as a direct result of their very nature. However, they are more likely to produce a positive effect in patients than any reuptake inhibiting antidepressant family (for example, NARI drugs, TCA drugs and SSNaRI drugs).
Unlike MAOI antidepressants, dietry restrictions are not strictly necessary when being treated with RIMA drugs, although eating large amounts of tyramine rich foods is probably not the greatest idea in the world; too much tyramine can technically cause a hypertensive crisis, a spike in blood pressure that leads to headaches and in the worst case a stroke; the chances of this with these drugs though is pretty remote.
Monoamine oxidase inhibitors in general aren't the smartest things to combine with other antidepressants or for that matter other drugs in general. In particular, they should not be mixed with antidepressants that inhibit the reuptake of serotonin for fear of inducing a potentially fatal condition known as serotonin syndrome and many antidepressants such as tricyclics can cause, just as tyramine can, a hypertensive crisis. Emergency pain killers aren't good things to be given either, so you might want to carry a medic alert on your person. Typically, your doctor will give you a small amount of an antidote that will combat and hopefully avert any hypertensive crisis by lowering your blood pressure; one example is a drug called nifedipine (marketed as Adalat®) which can be supplied as liquid capsules; pop one in your mouth, bite it and the drug will be absorbed extremely quickly indeed, kind of like an injection. Again, these are not really needed for RIMA therapy, but they can be reassuring to have.
Befloxatone
I have no information on this drug at this time.
Brofaromine
Brofaromine is not currently available to patients worldwide, which is a pity considering the promise it has shown. Not only does this drug act as a reversible and selective monoamine oxidase inhibitor, it also exhibits an ability to act as a selective serotonin reuptake inhibitor; this means that the drug is likely to be effective in a comparatively large number of patients. Additionally, brofaromine has been shown to exhibit relatively few side effects compared with the average antidepressant at the time of writing.
Moclobemide
Currently the only RIMA available for conventional treatment, moclobemide lacks the major side effects of its irreversible brethren (MAOI antidepressants) yet retains a greater chance of success than conventional antidepressants.
Generally considered to be less effective at combating depressive symptoms than true (irreversible) MAOI antidepressants, moclobemide still plays a valuable role as a compromise medication, one that does not require those being treated with it to conform to a special diet or to refrain from most over the counter medications.
Moclobemide is known to aggravate present psychotic symptoms in some cases so sufferers should proceed with caution. The most common side effects are a dry mouth (9.2%), headaches and/or feelings of pressure in the head (8% chance), insomnia and/or sleep disturbances (7.3%), nausea (5.2%), dizziness (5.1%) and tremor (5.0%).
Toloxatone
I have no information on this drug at this time.