McKenna's Pharmacology for Nursing, 2e

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P A R T 4  Drugs acting on the central and peripheral nervous systems

ANTIMANIC DRUGS Mania, at the opposite pole from depression, occurs in individuals with bipolar disorder, who experience a period of depression followed by a period of mania. The cause of mania is not understood, but it is thought to be an overstimulation of certain neurons in the brain. The mainstay for treatment of mania has always been lithium ( Lithicarb , Quilonum ). Today, many other drugs are used successfully in treating bipolar disorders, including aripiprazole ( Abilify ), olanzapine ( Zyprexa , Zyprexa Zydis ), quetiapine ( Seroquel ) and ziprasidone ( Zeldox ), which are atypical antipsychotics; and lam- otrigine ( Lamictal ), an antiepileptic agent discussed in greater detail in Chapter 23. These new approvals were the first advances since the 1970s in the treatment of bipolar disorder (see Table 22.2). Lithium salts ( Lithicarb , Quilonum ) are taken orally for the management of manic episodes and prevention of future episodes. These very toxic drugs can cause severe CNS, renal and pulmonary problems that may lead to death. Despite the potential for serious adverse effects, lithium is used with caution because it is consistently effective in the treatment of mania. The therapeutically effective serum level is 0.6 to 1.2 mEq/L. Therapeutic actions and indications Lithium functions in several ways. It alters sodium transport in nerve and muscle cells; inhibits the release of noradrenaline and dopamine, but not serotonin, from stimulated neurons; increases the intraneuronal stores • Drugs in this group should be taken exactly as prescribed. Because these drugs affect many body systems, it is important that you have medical checkups regularly. • Common effects of these drugs include: • Dizziness, drowsiness and fainting: Avoid driving or performing hazardous or delicate tasks that require concentration if these occur. Change position slowly. The dizziness usually passes after 1 to 2 weeks of drug use. • Pink or reddish urine (with phenothiazines): These drugs sometimes cause urine to change colour. Do not be alarmed by this change; it does not mean that your urine contains blood. • Sensitivity to light: Bright light might hurt your eyes and sunlight might burn your skin more easily. Wear sunglasses and protective clothing when you must be out in the sun. • Constipation: Consult with your healthcare provider if this becomes a problem. • Report any of the following conditions to your healthcare provider: sore throat, fever, rash, tremors, weakness and vision changes.

of noradrenaline and dopamine slightly; and decreases intraneuronal content of second messengers. This last mode of action may allow it to selectively modulate the responsiveness of hyperactive neurons that might con- tribute to the manic state. Although the biochemical actions of lithium are known, the exact mechanism of action in decreasing the manifestations of mania are not understood. Pharmacokinetics Lithium is readily absorbed from the GI tract, reaching peak levels in 30 minutes to 3 hours. It follows the same distribution pattern in the body as water. It slowly crosses the blood–brain barrier. Lithium is excreted from the kidney, although about 80% is reabsorbed. During periods of sodium depletion or dehydration, the kidney reabsorbs more lithium into the serum, often leading to toxic levels. Therefore, people must be encouraged to maintain hydration while taking this drug. Lithium crosses the placenta and enters breast milk, and has been associated with congenital abnormalities (see Contra­ indications and cautions). Contraindications and cautions Lithium is contraindicated in the presence of hyper­ sensitivity to lithium. In addition, it is contraindicated in the following conditions: significant renal or cardiac disease that could be exacerbated by the toxic effects of the drug ; a history of leukaemia; metabolic disorders, including sodium depletion; dehydration; and diuretic use because lithium depletes sodium reabsorption and • Tell any doctor, nurse, midwife or other healthcare provider that you are taking this drug. • Keep this drug and all medications out of the reach of children. • Avoid the use of alcohol or other depressants while you are taking this drug. You also may want to limit your use of caffeine if you feel very tense or cannot sleep. • Avoid the use of over-the-counter drugs while you are on this drug. Many of them contain ingredients that could interfere with the effectiveness of your drug. If you feel that you need one of these preparations, consult with your healthcare provider about the most appropriate choice. • Take this drug exactly as prescribed. If you run out of medicine or find that you cannot take your drug for any reason, consult your healthcare provider. After this drug has been used for a period of time, additional adverse effects may occur if it is suddenly stopped. This drug dosage will need to be tapered over time.