McKenna's Pharmacology for Nursing, 2e

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C H A P T E R 3 6 Adrenocortical agents

M ineralocorticoids Mineralocorticoids (Table 36.3) affect electrolyte levels and homeostasis. These steroid hormones, such as aldosterone, directly affect the levels of electrolytes in the system. The classic mineralocorticoid is aldosterone. Aldosterone holds sodium—and with it, water—in the body and causes the excretion of potassium by acting on the renal tubule. Aldosterone is no longer available for pharmacological use. Mineralocorticoids that are available include cortisone ( Cortate ), fludrocortisone ( Florinef ) and hydrocortisone ( Solu-Cortef ). Therapeutic actions and indications The mineralocorticoids increase sodium reabsorption in renal tubules, leading to sodium and water reten- tion, and increase potassium excretion (see Figure 36.2). Fludrocortisone is a powerful mineralocorticoid and is preferred for replacement therapy over cortisone and hydrocortisone; it is used in combination with a glucocorticoid. Hydrocortisone and cortisone also exert mineralocorticoid effects at high doses; however, this effect is not usually enough to maintain electro- lyte balance in adrenal insufficiency. These drugs are indicated (in combination with a glucocorticoid) for replacement therapy in primary and secondary adrenal insufficiency. They are also indicated for the treatment of salt-wasting adrenogenital syndrome when taken with appropriate glucocorticoids. See Table 36.3 for usual indications for each mineralocorticoid. Pharmacokinetics These drugs are absorbed slowly and distributed throughout the body. They undergo hepatic metabolism to inactive forms. They are known to cross the placenta and to enter breast milk. They should be avoided during pregnancy and breastfeeding because of the potential for adverse effects in the fetus or baby. Contraindications and cautions These drugs are contraindicated in the presence of any known allergy to the drug to avoid hypersensitiv- ity reactions ; with severe hypertension, heart failure or cardiac disease because of the resultant increased • Because this drug affects your body’s natural defences, you will need special care during any stressful situations. You may want to wear or carry medical identification showing that you are taking this medication. This identification alerts any medical personnel taking care of you in an emergency to the fact that you are taking this drug.

blood pressure ; and with breastfeeding due to potential adverse effects on the baby . Caution should be used in pregnancy because of the potential for adverse effects to the fetus , in the presence of any infection, which will alter adrenal response , and with high sodium intake because severe hypernatraemia could occur . Adverse effects Adverse effects commonly associated with the use of mineralocorticoids are related to the increased fluid volume seen with sodium and water retention (e.g. headache, oedema, hypertension, heart failure, arrhythmias, weakness) and possible hypokalaemia. Allergic reactions, ranging from skin rash to anaphy- laxis, have also been reported. Clinically important drug–drug interactions Decreased effectiveness of salicylates, barbiturates, hydantoins, rifampicin and anticholinesterases has been reported when these drugs are combined with miner- alocorticoids. Such combinations should be avoided if possible, but if they are necessary, the person should be monitored closely and the dose increased as needed. • It is important to have regular medical follow-up. If your drug dose is being tapered, notify your healthcare provider if any of the following occurs: fatigue, nausea, vomiting, diarrhoea, weight loss, weakness or dizziness. • Keep this drug out of the reach of children. Do not give this medication to anyone else or take any similar medication that has not been prescribed for you. Prototype summary: Fludrocortisone Indications: Partial replacement therapy in cortical insufficiency conditions, treatment of salt-losing adrenogenital syndrome; off-label use: treatment of hypotension. Actions: Increases sodium reabsorption in the renal tubules and increases potassium and hydrogen excretion, leading to water and sodium retention. Pharmacokinetics: Route Onset Peak Duration PO Gradual 1.7 hours 18–36 hours T 1/2 : 3.5 hours; metabolised in the liver and excreted in the urine. Adverse effects: Frontal and occipital headaches, arthralgia, weakness, increased blood volume, oedema, hypertension, heart failure, rash, anaphylaxis.