Medications for antidiuretic hormone (ADH) disorders: Nursing pharmacology

Antidiuretic hormone, or ADH for short, is the primary hormone that regulates fluid balance in the body, and is normally produced by the hypothalamus and stored in the posterior pituitary, which are both located within the brain.

Now, ADH disorders arise when the pituitary releases too much or too little of it. These disorders include diabetes insipidus, which results from a decrease in ADH; and syndrome of inappropriate ADH secretion, or SIADH for short, which results from an increased secretion of ADH.Okay, so on one end of the spectrum, there’s ADH deficiency, which causes diabetes insipidus.

This disorder is treated with ADH replacement therapy, which involves medications like vasopressin, which is a synthetic form of ADH, and desmopressin, which is a vasopressin analogue.Both medications can be administered subcutaneously.

In addition, vasopressin can be administered intramuscularly, and desmopressin can be administered orally, intranasally, or intravenously.

Once administered, these medications act on the kidneys by mimicking the actions of ADH, ultimately promoting the reabsorption of water at the distal convoluted tubule and collecting duct.Now, these medications may cause side effects like headache, lethargy, and flushing.

Other important side effects include nausea, vomiting, heartburn, and abdominal cramps. In addition, clients who take vasopressin may present with urticaria and vertigo.

These medications also cause vasoconstriction, resulting in cardiovascular side effects. Clients on vasopressin may experience chest pain, and even myocardial infarction.

On the other hand, clients taking desmopressin may develop hypertension, tachycardia, and palpitations. In addition, desmopressin may cause anaphylactic reactions.

Finally, desmopressin can lead to water intoxication and hyponatremia, which can cause seizures and fatal brain dysfunction.

Alright, now these medications are contraindicated in hyponatremia, and that’s a boxed warning, since it can lead to seizures!

In addition, they should be used with caution in clients with severe renal disease, and those with coronary artery disease, since they may cause vasoconstriction.

In addition, vasopressin should be used with caution in clients who experience migraines, seizures, or asthma. On the other hand, desmopressin is also used with caution in those with nephrogenic diabetes insipidus, as well as in clients with cystic fibrosis, hypertension, and electrolyte imbalances.On the opposite end of the spectrum, there’s ADH excess, which causes syndrome of inappropriate antidiuretic hormone secretion, or SIADH for short.

This disorder is treated with vasopressin receptor antagonists, such as conivaptan, which is administered intravenously, and tolvaptan, which is given orally.

Once administered, these medications inhibit the action of ADH, ultimately promoting water excretion in urine.Side effects of vasopressin receptor antagonists include nausea, vomiting, constipation, as well as polyuria and dehydration.

In addition, clients taking conivaptan may experience headache, confusion, insomnia, and increased thirst. Some clients may also develop injection site reactions, orthostatic hypotension, and electrolyte abnormalities, such as hypokalemia, hypomagnesemia, and hyponatremia.

On the other hand, clients taking tolvaptan may present with dizziness and fever, as well as electrolyte abnormalities like hyperkalemia and hypernatremia, and may develop hyperglycemia.

Finally, tolvaptan may cause strokes, ventricular fibrillation, disseminated intravascular coagulation or DIC, and bleeding, as well as pulmonary embolism, respiratory depression, and rhabdomyolysis.

Lastly, tolvaptan has a boxed warning for hepatotoxicity and for osmotic demyelination syndrome, especially if the hyponatremia from SIADH is corrected too quickly.Finally, vasopressin receptor antagonists are contraindicated in clients presenting with hypovolemia, and should be used with caution during pregnancy and breastfeeding.

Additional precautions for conivaptan include orthostatic hypertension, heart failure, and renal disease. On the other hand, tolvaptan is also contraindicated in clients with anuria or autosomal dominant polycystic kidney disease, and should be used with caution also in children and elderly clients.

In addition, tolvaptan should be administered in specialized care settings, where blood sodium levels can be carefully monitored during treatment.

Finally, caution should be taken in clients with dehydration, hyperkalemia, malnutrition, alcoholism, or hepatic disease.Okay, when caring for a client prescribed either ADH replacement therapy or a vasopressin receptor antagonist, first assess their vital signs and weight, and evaluate their hydration status, noting signs of dehydration or edema and fluid overload, as well as signs and symptoms of either hypo- or hypernatremia.

Next review their current laboratory test results, including BUN, creatinine, as well as electrolytes like sodium and potassium, hepatic function, and blood glucose, as well as blood and urine osmolality.Now, on the one hand, if your client is diagnosed with central diabetes insipidus and is prescribed desmopressin, explain how the medication replaces a missing hormone called ADH, which normally promotes water reabsorption in the kidneys, and thus regulates and decreases the amount of urine they produce.

For clients using the nasal spray, instruct them to first gently blow their nose before administering the medication. Then, show your client how to prime the bottle before administering the medication.

Ask them to tilt their head back slightly, and insert the tip of the nose piece into one nostril, while closing the other nostril by pressing lightly with their finger; next, instruct them to breathe in gently through their nose while spraying once.

Remind them to keep the nosepiece clean by wiping it with a clean tissue, and to avoid blowing their nose afterwards. Teach them to monitor their daily fluid intake and urine output, and stress the importance of contacting their healthcare provider right away if their urine output is not within the recommended daily amount.

Also, let them know that the medication may cause side effects like irritation to their nasal passages, as well as nausea and abdominal cramps, and advise them to report these if they persist.

Lastly, teach them to recognize and immediately report symptoms of water intoxication and low sodium, such as headache, weakness, and confusion.Now, on the other hand, if your client is diagnosed with SIADH and is prescribed tolvaptan, explain how the medication inhibits water reabsorption in the kidneys, which increases the amount of urine they produce.

Stress the importance of taking the medication once daily with or without food, but to avoid consuming grapefruit or drinking grapefruit juice while taking this medication.

Stress the importance of contacting their healthcare provider right away if they experience symptoms of liver damage, such as fatigue, anorexia, abdominal pain, dark urine, or yellowing of the eyes or skin.

Also, teach them to monitor their fluid intake and urine output, as well as to adhere to prescribed fluid restrictions, and to recognize and report symptoms of elevated sodium, such as muscle pain or weakness, mood changes, or a fast heartbeat, and to seek immediate medical attention if they are unable to pass urine.Finally, during treatment, continue to monitor your client’s weight, vital signs, fluid intake and output, blood osmolality, sodium, BUN, and creatinine.

Finally, be sure to closely monitor for side effects and for the therapeutic effect of normalized fluid and electrolyte balance.Alright, as a quick recap… ADH deficiency causes diabetes insipidus, and is treated with ADH replacement therapy like vasopressin and desmopressin, which increase water reabsorption in the kidneys, ultimately decreasing water excretion.

Side effects include nausea and abdominal cramps, irritation to their nasal passages, as well as water intoxication and hyponatremia.

On the other hand, too much ADH causes SIADH, and is treated with vasopressin receptor antagonists like conivaptan and tolvaptan, which decrease water reabsorption in the kidneys, ultimately increasing water excretion.

Side effects include dehydration, increased thirst, and hypernatremia. When caring for a client receiving medications for ADH disorders, nursing considerations include monitoring for side effects and evaluating the therapeutic response of normalized fluid and electrolyte balance.

Client teaching centers around client understanding of the medication’s actions and safe self-administration, as well as self-monitoring, and learning to recognize side effects that need to be immediately reported to their healthcare provider.