Anticholinergic effects antipsychotics

It is also very important, if possible, to discontinue or lower the doses of drugs with anticholinergic effects antihistamines, antipsychotics, antidepressants, uro-logic spasmolytics, anti-arrhythmics, drugs for Parkinson s disease and more. Prophylactic treatment against Candida infection, bacteria and caries can also be useful (Mouly et al. 2007). 

Antipsychotics. Antipsychotic medications are also called major tranquilizers. It is for the tranquilizing effect that they have been used to treat agitation. The earliest antipsychotics, especially thioridazine (Mellaril), proved to be effective in reducing agitation however, this comes at the price of further impairing cognition due to its profound anticholinergic effects. 

The high potency antipsychotic haloperidol (Haldol) provides the same calming effects with minimal anticholinergic effects. Although haloperidol is very effective, dementia patients are quite sensitive to its extrapyramidal effects. These include stiffness, shuffling gait, a mask-like facial appearance, and involuntary movements. To minimize these effects, haloperidol is used in very low doses (0.5-1.0mg) when treating those with dementia. 

Antipsychotic agent Approx. equiv. dose (mg) Usual oral adult daily dose range (mg) Sedation EPS Anticholinergic effects ... 

The piperazines include fluphenazine, trifluoperazine, prochlorperazine, perazine and perphenazine. They are agents with a high antipsychotic potency with less pronounced anticholinergic effects. However their potential to produce extrapyramidal effects is more pronounced. 

Tricyclic antidepressants are notorious for their risk to be involved in drug-drug interactions. Additive anticholinergic effects can be expected in combination with antihistamines, antipsychotics and anticholinergic-type anti-Parkinson agents. Hepatic enzyme-inducing agents increase their hepatic metabolism while enzyme inhibitors may potentiate the effects of tricyclics. Concomitant use with monoamine oxidase inhibitors will produce hypertension, hyperpyrexia and convulsions. 

The case in context Clozapine is a newer antipsychotic that can, like other agents in its class, produce antimuscarinic side effects. Although Ms. Doe had not complained of anticholinergic effects prior to beginning treatment with a moderate dose of diphenhydramine, it is likely that the additive anticholinergic effects of clozapine and diphenhydramine resulted in urinary retention. 

High-potency antipsychotic with a relatively high incidence of EPS, but a low incidence of sedation, anticholinergic effects, and cardiovascular effects... 

As noted above, several antipsychotics have prominent anticholinergic effects. Side effects due to anticholiner-gia may include dry mouth, blurred vision, constipation, urinary retention, and tachycardia. 

Antipsychotic agents may have several cardiovascular effects. Medication-induced hypotension is generally more problematic with lower-potency neuroleptics than with other antipsychotics and appears to be mediated through tti-adrenergic blockade. Besides increases in heart rate that may be the result of hypotension, antipsychotics with appreciable anticholinergic effects (see Clinical Implications, below) can lead to tachycardia (Gutgesell et ah, 1999). 

Acute angle closure and difficulty with accommodation can occur from the anticholinergic effects of antipsychotic agents. In addition, pigment deposits may develop in the cornea and lens. Pigmentary retinopathy has been reported with thioridazine. Keratopathy and corneal edema may occur occasionally during pharmacotherapy with chlorpromazine and fluphenazine... 

Some of the expected changes with age, such as the reduction in cholinergic neurons or the presence of Alzheimer s dementia, may accentuate the anticholinergic effects of many antipsychotics and antidepressants. Thus, elderly patients have increased sensitivity to these properties, often resulting in a central anticholinergic syndrome (267). This condition is characterized by the loss of immediate memory, confusion, disorientation, and florid visual hallucinations, at times superimposed on other psychoses, such as schizophrenia or psychotic depression. 

Antipsychotics produce more important pharmacodynamic than pharmacokinetic interactions because of their multiple effects. Additive effects may occur when these drugs are combined with others that have sedative effects, a-adrenoceptor-blocking action, anticholinergic effects, and—for thioridazine and ziprasidone—quinidine-like action. 

Some antipsychotics also produce significant anticholinergic effects, manifested by a variety of symptoms such as blurred vision, dry mouth, constipation, and urinary retention. Fortunately, these problems are usually self-limiting as many patients become tolerant to the anticholinergic side effects while remaining responsive to the antipsychotic properties. 

Perhaps because of their anticholinergic effects (cf benztropine, Chapter 28 Pharmacologic Management of Parkinsonism Other Movement Disorders), some of the Hi antagonists have significant acute suppressant effects on the parkinsonism symptoms associated with certain antipsychotic drugs. 

INDIRECT ANTIPSYCHOTICS 1. Case reports of paralytic ileus with trifluoperazine and methylphenidate 2. Case report of acute dystonias with haloperidol and dexamfetamine 3.1 efficacy of chlorpromazine when dexamfetamine was added 1. Additive anticholinergic effect 2. Uncertain possibly due to t dopamine release 3. Uncertain 1. Watch for signs of altered bowel habit 2. Warn patients of this rare interaction 3. Avoid co-administration... 

Also note that the potential for an interaction between drugs does not preclude their concurrent use. Certain combinations are routinely prescribed without problems in many patients (as with lithium and antipsychotics), whereas others are contraindicated due to the severity of the interaction (for example, MAOIs and SSRIs). However, whenever psychiatric medications are coadministered, the additive potential of central nervous system depression and anticholinergic effects must be considered. 

Phenothiazine antipsychotic drugs Anticholinergic effects Ca " channel blockade ... 

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