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CHAPTER 15 ■ Schizophrenia Spectrum and Other Psychotic Disorders
TABLE 15–4 Agents Used to Treat Extrapyramidal Side Effects of Antipsychotic Drugs Indication
Antiparkinsonian agents: Used to treat parkinsonism of various causes and drug-induced extra- pyramidal reactions. VMAT2 inhibitors: Used to treat tardive dyskinesia Antiparkinsonian agents: Restores the natural balance of acetylcholine and dopamine in the CNS. The imbalance is a deficiency in dopamine that results in excessive cholinergic activity. VMAT2 inhibitors: mechanism of action unknown Antiparkinsonian agents are contraindicated in individuals with hypersensitivity. Anticholinergics should be avoided by individuals with angle-closure glaucoma; pyloric, duodenal, or bladder neck obstructions; prostatic hypertrophy; or myasthenia gravis. Caution should be used in administering these drugs to clients with hepatic, renal, or cardiac insufficiency; elderly and debilitated clients; those with a tendency toward urinary retention; and those exposed to high environmental temperatures.
Action
Contraindications/ Precautions
VMAT2 inhibitors are contraindicated in individuals with hypersensitivity. Warnings include risk for somnolence and prolongation of QT interval; may cause parkinsonism in patients with tardive dyskinesia. Common Side Effects Anticholinergic effects (dry mouth, blurred vision, constipation, paralytic ileus, urinary retention, tachycardia, elevated temperature, decreased sweating), nausea/GI upset, sedation, dizzi- ness, orthostatic hypotension, exacerbation of psychoses. Side effects with VMAT2 inhibitors include hypersensitivity, somnolence, QT interval prolonga- tion, parkinsonian symptoms, weight gain, increased blood glucose, anxiety. CHEMICAL CLASS GENERIC (TRADE) NAME DAILY DOSAGE RANGE (MG) Anticholinergics Benztropine (Cogentin) Biperiden (Akineton) Trihexyphenidyl 1–8 2–6 1–15
Antihistamines
Diphenhydramine (Benadryl)
25–200
Dopaminergic Agonists
Amantadine
200–300
VMAT2 inhibitor
Valbenazine Deutetrabenazine
40–80 6–48
CNS: central nervous system; GI: gastrointestinal; VMAT2: vesicular monoamine transporter type 2.
■■ Rise slowly from a sitting or lying position to pre- vent a sudden drop in blood pressure. ■■ Take frequent sips of water, chew sugarless gum, or suck on hard candy, if dry mouth is a problem. Good oral care (frequent brushing, flossing) is very important. ■■ Consult the physician regarding smoking while on antipsychotic therapy. Smoking increases the metabolism of antipsychotics, requiring an adjust- ment in dosage to achieve a therapeutic effect. ■■ Dress warmly in cold weather and avoid extended exposure to very high or low temperatures. Body tem- perature is harder to maintain with this medication. ■■ Avoid drinking alcohol while on antipsychotic ther- apy. These drugs potentiate each other’s effects. ■■ Avoid taking other medications (including over- the-counter products) without the physician’s approval. Many medications contain substances
that interact with antipsychotics in a way that may be harmful. ■■ Be aware of possible risks of taking antipsychot- ics during pregnancy. Antipsychotics are thought to cross the placental barrier; if so, a fetus could experience adverse effects of the drug. Neonates are at increased risk for EPS and withdrawal after delivery when exposed to antipsychotics in the third trimester. Inform the physician immediately if pregnancy occurs, is suspected, or is planned. ■■ Be aware of side effects of antipsychotic drugs. Refer to written materials furnished by health-care providers for safe self-administration. ■■ Continue to take the medication even if feeling well and as though it is not needed. Symptoms may return if medication is discontinued. ■■ Carry a card or other identification at all times describing medications being taken.
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