Atypical Antipsychotic
Also referred to as a Novel Antipsychotics
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.
Regarded as second generation antipsychotics, atypical antipsychotics are the first line of defence against psychotic illnesses and some have also proven useful in the treatment of manic and/or depressive illnesses. Compared to typical antipsychotics, these drugs induce far fewer unwanted side effects, especially ones related to unwanted movement.
The first drug of this family was Clozapine, discovered in the 1950s and first marketed in the 1970s; interestingly, it remains the most powerful antipsychotic of this family. Recently, more inoffensive atypical antipsychotics have surfaced, including aripiprazole, quetiapine and olanzapine, all introduced in the last twenty years.
Generally speaking, the older typical antipsychotics are more effective in treating psychosis, but also tend to cause more side effects.
Amisulpride
A curious medication, amisulpride is thought to have its antipsychotic effect as a result of dopamine antagonism; oddly, it has the exact opposite effect in low doses (around 50mg or less per day) and as such can be used as a purely antidepressive drug in small quantities. The drug typically causes weight gain. At the time of writing, this medication is not available to patients in the USA.
Asenapine
The only thing that I know about this drug is that it is also effective in combating clinical depression. It is still under development.
Clozapine
The first atypical antipsychotic to be developed, clozapine started out life as a heavy duty antidepressant but was noted to also have a positive effect on psychotic disorders. Introduced in 1971, the drug was withdrawn from the market four years later, following a number of fatal cases of agranulocytosis under clozapine therapy. The drug disappeared from psychiatric circles for many years but was reintroduced when studies showed clozapine to be more effective in the treatment of psychosis than virtually every other antipsychotic available (including at the time of writing); it was especially useful in the treatment of treatment resistant psychosis. Subsequent uses include the treatment of chronically suicidal patients and as a treatment for tardive dyskinesia.
The drug is sedative and will almost certainly cause patients to gain weight; typical side effects include a lowered threshold for seizures in general, drooling, constipation, tremor and muscle stiffness amongst others.
Clozapine is not widely prescribed to patients indeed, it is a rare drug to be given. The reason for this is the chance of potentially fatal side effects (such as agranulocytosis, whose incident rate is 1% during the first 6 months of therapy and 0.01% from then on) that demand regular blood tests and close monitoring during therapy. As a result, the dosage should be started off very gradually, steadily building up in increments of not more than 25mg a night to the target dose.
Although clozapine is referred to as an atypical antipsychotic, such a label is a drastic understatement; many consider the drug to be in a class of its own.
Loxapine
Although mostly classified as a typical antipsychotic, many researchers believe that loxapine might in fact be atypical in nature.
Olanzapine
The second atypical antipsychotic to be released, olanzapine is often referred to as the chemical kosche due to its sedative and tranquillising properties; it is structurally similar to the drug clozapine, of the same class.
Generally speaking, olanzapine is a highly regarded drug - it's generally well tolerated, is largely effective and has relatively few serious problems associated with it; as such, it is one of the most widely prescribed drugs of its class. The drug also possesses antidepressant qualities and is often mixed with the SSRI antidepressant fluoxetine to produce a substance marketed as Symbyax®.
Unfortunately, olanzapine will probably cause weight gain and (as was previously mentioned) will almost certainly cause drowsiness as well.
Paliperidone
Approved in 2006 for the treatment of psychotic disorders, paliperidone is in essence a variation on the atypical antipsychotic risperidone.
Quetiapine
Generally regarded as the most soft of all the antipsychotics (typical or atypical), quetiapine is strongly sedative and takes a fair while to present positive effects on the patients state of mind. The drug also sports a great ability to be upped in dosage very quickly compared to other drugs of the same class. It is often used as a long term treatment for insomnia and is intended as a treatment for depressive disorders (due to a decent antidepressive effect) and for anxiety disorders.
Risperidone
Usually regarded as the first line antipsychotic, risperidone is stimulant and sports antidepressive effects as well as the obvious; it is the most prescribed antipsychotic in most of the developed world.
Typical side effects include weight gain, stimulation, anxiety, nausea and/or vomiting, dizziness, tremor, insomnia, drooling and muscle stiffness and/or pain; it also affects the patients libido more often than not.
A word to the wise - the tablets taste foul. Ye be warned...
Sertindole
No longer available to the mass market, sertindole was introduced fairly recently before its fall from power in late 1998. Research indicated that the drug was useful in the treatment of anxiety related disorders yet did not have a sedative effect.
Sulpiride
Chemically close to the drug amisulperide, sulpride is an antipsychotic medication with marked antidepressant capabilities. It is still commonly prescribed across the world, but at the time of writing it is not yet available to the USA. Sulpride is stimulant and should not be taken any later than 4pm to avoid problems with sleep; side effects for this drug tend not to be dosage related.
Ziprasidone
The fifth drug of this family to be successfully marketed, ziprasidone is a recent addition to the atypical family and is establishing itself with relative ease. Unlike many drugs, this medication doesn't have an overly obvious or dominant side effect profile - patients react to the medication on a fairly individual basis. Unlike other drugs of the same family, ziprasidone also impacts on the monoamine neurotransmitter noradrenaline; the consequence of this is unknown.
Unfortunately, ziprasidone can cause birth defects and as such should not be administered to pregnant women. The drug can be stimulating or sedative, depending on the patient and as such can cause fatigue or insomnia, again, depending on the patient. The medication tends to cause weight loss, which may be viewed as beneficial.
Zotepine
Novel in that it impacts on the monoamine neurotransmitter noradrenaline, zotepine is especially useful in combatting the negative symptoms of schizophrenia and related psychotic illnesses. The medication does typically cause weight gain and that to an extent that rivals the older typical antipsychotics. It is also sedative, with somnolence being the most common side effect associated with this medication.