Famotidine Nursing Pharmacology and Implications
Famotidine treats stomach and intestine ulcers and prevents intestinal ulcers from returning after they healed. This medicine also addresses issues with the stomach and throat (esophagus), such as erosive esophagitis, gastroesophageal reflux disease-GERD, and Zollinger-Ellison syndrome.
Famotidine functions by reducing the quantity of acid produced by the stomach. It alleviates symptoms such as persistent coughing, stomach cramps, heartburn, and difficulties in swallowing. Famotidine belongs to the H2 blocker or histamine H2 receptor antagonists.
Famotidine reduces stomach acid production, acid concentration, pepsin content, and the volume of gastric output. Famotidine suppresses baseline and nocturnal stomach acid production and acid secretion induced by meals, coffee, insulin, and pentagastrin.
Famotidine could also be classified as either prescription or over-the-counter medication. The prescription type of famotidine is available as a tablet and a suspension (liquid) taken orally. It is typically taken once daily at bedtime or two to four times per day.
In contrast, over-the-counter famotidine is marketed as a chewable tablet and an oral capsule. It is usually taken once or twice a day, 15 to 60 minutes before eating or drinking foods or beverages that may induce heartburn, for better results.
Famotidine’s therapeutic effectiveness is dose-dependent, with the highest dose having the most extended duration of action and the most significant inhibitory effect on gastric acid output. The beginning of action after oral administration is within one hour, and the maximal effect is obtained within 1-3 hours. The impact lasts approximately 10-12 hours.
Indications of Famotidine
Famotidine is approved for treating active duodenal ulcers, active gastric ulcers, symptomatic non-erosive gastroesophageal reflux disease (GERD), and erosive esophagitis associated with GERD in pediatric and adult patients with bodyweight 40 kg and above.
Another famotidine’s indications are managing pathological hypersecretory disorders such as Zollinger-Ellison Syndrome, multiple endocrine neoplasias, and preventing duodenal ulcer recurrence in adults.
Famotidine in the intravenous formulation is offered for some hospitalized patients with pathologic hypersecretory disorders or persistent ulcers or as a short-term substitute to oral dose form in individuals incapable of taking oral medication.
Over-the-counter famotidine is used to alleviate and prevent heartburn caused by reflux disease in both children and adults. Off-label indications of famotidine include the reduction of NSAID-associated gastrointestinal symptoms, therapy of refractory urticarial, avoidance of stress ulcers in terminally ill patients, and symptomatic alleviation of gastritis.
Mechanism of Action of Famotidine
Proton pumps leak acid into the stomach lumen when H2 receptors on parietal cells are activated. Famotidine is a histamine H-receptor antagonist (H2RA) that adheres to the H-receptors on the basolateral membrane of the parietal cell in the stomach, thereby suppressing histamine activities.
Its pharmacologic effect suppresses gastric acid volume and concentration, resulting in gastric secretion regulation. Famotidine lowers stomach volume, acidity, and secretion triggered by food, coffee, insulin, and pentagastrin.
Pharmacokinetics of Famotidine
Famotidine has a prolonged onset of action that begins 90 minutes after administration. Famotidine, on the other hand, has a half-life of at least 540 minutes. Famotidine lowers acid secretion by 7.3 mmol per 30 minutes at its maximal effect, which occurs 210 minutes (3.5 hours) after ingestion.
- Absorption. Peak plasma concentrations of famotidine are reached within 2 to 4 hours of oral treatment; oral bioavailability ranges from 40 to 50%, owing primarily to inadequate absorption. The famotidine’s oral absorption is dose-independent between 5 and 40 mg.
- Bioavailability. Famotidine has an absolute bioavailability of 40-45% following oral administration, with absorption occurring primarily in the initial portion of the small intestine due to minimal intestinal permeability.
- Distribution. The distribution of famotidine in human body fluids and tissues has yet to be well studied. Famotidine is present in breast milk at the lowest amounts compared to other H2 receptor antagonists, with a steady-state distribution ranging from 1.0 to 1.3 L/kg.
- Metabolism. Famotidine has a minimal chance of undergoing first-pass metabolism. Hepatic metabolism eliminates 25-30% of the medication. The S-oxide metabolite is the only one found in humans.
- Elimination. About 65-70% of the entire administered dose of famotidine is eliminated via the kidneys, whereas 30-35% is eliminated by metabolism. Within 24 hours of oral or intravenous administration, famotidine is excreted significantly, 25-30% or 65-80% unaltered, via the renal pathway, mainly via active tubular secretion and glomerular filtration. The residual substance is eliminated through metabolic processes.
- Half-life. The elimination half-life of famotidine is approximately 2 to 4 hours. However, the half-life of famotidine in patients with impaired renal function is anticipated to increase nonlinearly.
- Renal Clearance. Renal clearance ranges between 250 and 450 mL/min, implying some tubular excretion. Famotidine is assumed to be primarily removed via both glomerular filtration and renal tubular secretion since the renal clearance rate surpasses the glomerular filtration rate.
Side Effects of Famotidine
A drug may have specific unwanted side effects in addition to its intended benefits. Not all of the listed side effects may happen at the same time, but they may necessitate medical treatment if they occur. The following are some of the rare side effects that may occur while taking famotidine:
- fussiness (applicable for infants who take famotidine)
The following are some of the possible severe side effects of famotidine:
- a rash on the skin
- Face, neck, tongue, lips, eyes, hands, feet, calves, or lower legs swelling
- breathing or swallowing difficulties
Some adverse effects may occur that might not necessitate medical treatment. These adverse effects may subside as the body responds to the medication. The doctor may also be able to advise the patient on how to avoid or mitigate some of these adverse effects. Consult the doctor if the following side effects persist or become bothersome.
Adverse Reactions of Famotidine
If the patient experiences symptoms of an allergic response to famotidine: hives; difficulty breathing; swelling of the face, lips, tongue, or neck, get emergency medical attention.
These are some of the other adverse reactions of famotidine:
- confusion, hallucinations, agitation, and exhaustion
- fast or hammering heartbeats, dizziness
- inexplicable muscle soreness, tenderness, or weakness, particularly if the patient has a fever, unusual weariness, or black urine.
Toxicity of Famotidine
Since famotidine is mainly eliminated via the kidney, patients with poor renal function may be at a higher risk of adverse effects. Dose adjustment is required in individuals who have moderate to severe renal impairment.
According to the product label for famotidine, oral doses up to 640 mg per day outside of FDA-approved doses have been given to adult patients with pathological hypersecretory states with no serious adverse outcomes.
Overdose cases are comparable to those observed in routine clinical practice. Overdose treatment should include eliminating unabsorbed medicines from the intestinal system, monitoring the patient, and providing supportive therapy.
Famotidine is categorized as pregnancy category B and should only be used if necessary during pregnancy. Famotidine is found in breast milk. A mother’s decision to breastfeed throughout therapy should be determined by balancing the risk to the infants and treatment advantages to the mother. Famotidine has one of the lowest quantities in break milk compared to other Histamine H2-receptor antagonists (H2RAs), making it one of the preferred medications for gastric acid disorders.
Contraindications Against Famotidine
Patients with severe hypersensitivity to famotidine or any formulation component should avoid using it. Given the cross-sensitivity of H2RAs, famotidine should not be prescribed to patients with a history of hypersensitivity to H2 blockers.
Furthermore, if the patient has difficulty and pain swallowing food, vomiting with blood, or black or bloody stools, the over-the-counter form of famotidine should not be utilized. Patients allergic to other acid reducers, have renal impairment, or are currently on other acid reducers should not take the over-the-counter famotidine.
Drug Interactions of Famotidine
Anticoagulants. These medications, when taken concomitantly, may increase the risk of severe and possibly fatal stomach or intestinal disorders such as ulcers or bleeding. The risk is higher in the elderly and those who have previously experienced stomach or intestinal ulcers or bleeding. These issues may emerge without warning.
Inotropic Agents. Famotidine increases the effect and blood level of inotropic agents by increasing gastric pH. However, these interactions only happen if both medications are taken in tablet form.
Protease Inhibitors. If these two medications are co-administered, the famotidine will most likely decrease the solubility of protease inhibitors. It is advisable to take these two medications at least 10 hours apart.
Biguanides. If these two medications are taken concomitantly, the effect or level of biguanides increases due to decreased renal clearance.
Antimalarials. Antimalarials increase the toxicity of famotidine when taken together. Antimalarials and famotidine may increase the risk of experiencing abnormal heart rhythm. These interactions apply to the IV form of the medications.
- Food Interactions
- Avoid consuming alcohol in excess or regularly while taking famotidine. Alcohol raises the likelihood of stomach discomfort.
- Caffeine use should be kept to a minimum while taking famotidine. Caffeine and other acidic beverages can cause gastric irritation.
- Consume famotidine with or without food. Food enhances bioavailability marginally but is not clinically significant.
- Disease Interactions
- Famotidine and GI bleeding have a significant relationship. Histamine H2 receptor antagonists should not be taken if there is bloody vomit or bloody or black feces. These are potentially dangerous conditions, and the diagnosis must be ruled out first.
- Patients with renal impairment should have dosage adjustment if he or she needs to take famotidine.
Nursing Considerations for Patients on Famotidine
- Assess if the patient has a history of allergy to H2 antagonists to avoid a possible adverse reaction.
- Evaluate if the patient has impaired renal or hepatic function, which could significantly affect the drug’s metabolism and excretion.
- Have a detailed description of the GI problem, including the length of time the disorder has been present.
- Conduct a medical evaluation to determine the appropriate use of the drug and the possibility of underlying medical problems.
- Confirm the patient’s current pregnancy and lactation status.
- Perform a physical examination before initiating therapy to establish baseline information, evaluate therapy effectiveness, and assess any side effects related to drug therapy.
- To detect unfavorable responses, inspect the patient’s skin for lesions or rashes.
- Maintain therapeutic levels. To achieve therapeutic levels when the medicine is most needed, take it with or before meals and bedtime (precise timing varies by product).
- To avoid significant toxicity, arrange a lower dose of the medication in hepatic or renal impairment cases.
- When delivering IV doses, constantly monitor the patient to detect potentially significant side effects, such as heart arrhythmias.
- Because of the medications’ impact on liver enzyme systems, evaluate the patient carefully for any potential drug-drug interactions if given in combination with other drugs.
- To reduce the possibility of unpleasant consequences, provide comforts, such as analgesics, ready-access restroom facilities, and ambulation help.
- Reorient the patient regularly and implement safety measures if CNS effects occur to guarantee patient safety and increase patient tolerance of the medicine and drug effects.
- Advise the patient to arrange a regular follow-up to assess drug effects and underlying issues.
- Provide patients with encouragement and assistance to help them cope with the condition and the medication regimen.
- Educate patients on the medicine name, dosage, administration schedule, the necessity of spacing administration appropriately as directed, signs and symptoms of adverse effects, and strategies to avoid or prevent them.
- Keep track of the patient’s response to the medication, such as the drug’s effectiveness in relieving GI symptoms, healing the ulcer, and preventing the progression and recurrence of the ulcer.
- Check for famotidine’s adverse effects, including dizziness, disorientation, delusions, GI changes, irregular heartbeats, hypotension, and gynecomastia.
- Assess if the patient can name the drug, the proper dosage, adverse reactions to watch for, and specific measures to prevent them.
- Keep track of the appropriateness of the comfort measures and the patient’s adherence to the regimen.
Nursing Care Plan for Patients on Famotidine
Possible Famotidine Nursing Diagnoses
- Risk for Disturbed Thought Process
- Risk for Injury related to possible adverse effects (hypotension, lightheadedness, or disorientation)
- Constipation/ Diarrhea
|Famotidine Nursing Interventions||Rationale|
|Assess the patient for signs and symptoms of heartburn, ulcer, and/or gastroesophageal reflux disease (GERD).||To confirm the indication for administering famotidine, which is prescribed for patients with peptic, duodenal and gastric ulcers, as well as GERD and esophagitis.|
|Check the patient’s allergy status.||Previous allergic reactions to famotidine or other histamine H2 receptor antagonists may render the patient unable to take them. Alternatives to famotidine should therefore be considered in case of allergy.|
|Perform a focused physical assessment of the patient’s abdomen through inspection, palpation, and auscultation of bowel sounds.||To confirm the indication for administering famotidine, and to assess the patient’s GI motility.|
|Assess the patient’s mucous membranes and their ability to swallow.||To check for any potential problems with administration, hydration, and absorption.|
Ensure that the right form of famotidine is given (usually available in oral, liquid, and intravenous forms).
|Assess the patient’s bowel pattern and consistency.||Famotidine may cause either constipation or diarrhea.|
Nursing Planning and Intervention
|Famotidine Nursing Interventions||Rationale|
|Administer famotidine 15 to 60 minutes before meals and/or at bedtime with or without food.||To ensure optimal absorption and therapeutic action by famotidine.|
|Administer famotidine about 1 hour before or 2 hours after administering other oral medications, as prescribed.||The ideal spacing of famotidine and other oral medications will ensure adequate absorption of the drugs administered.|
|Educate the patient about the action, indication, common side effects, and adverse reactions to note when taking famotidine. Instruct the patient on how to self-administer famotidine.||To inform the patient on the basics of famotidine, as well as to empower him/her to safely self-administer the medication.|
|Monitor the patient’s bowel movement and commence the stool chart.||Famotidine may cause diarrhea or constipation. Early detection of either side effect can help institute a bowel program and relieve them effectively.|
|Famotidine Nursing Interventions||Rationale|
|Ask the patient to repeat the information about famotidine.||To evaluate the effectiveness of health teaching on famotidine.|
|Monitor the patient’s renal function.||To ensure that the famotidine did not cause any renal dysfunction, as elimination of the drug happens in the kidneys.|
|Monitor the patient’s response to famotidine.||To check for the relief of GI symptoms, as well as to see if the famotidine is effective or should be shifted to other H2 receptor antagonists due to an allergic reaction, severe side effects, or adverse reactions.|
Ackley, B. J., Ladwig, G. B., Makic, M. B., Martinez-Kratz, M. R., & Zanotti, M. (2020). Nursing diagnoses handbook: An evidence-based guide to planning care. St. Louis, MO: Elsevier. Buy on Amazon
Gulanick, M., & Myers, J. L. (2022). Nursing care plans: Diagnoses, interventions, & outcomes. St. Louis, MO: Elsevier. Buy on Amazon
Ignatavicius, D. D., Workman, M. L., Rebar, C. R., & Heimgartner, N. M. (2020). Medical-surgical nursing: Concepts for interprofessional collaborative care. St. Louis, MO: Elsevier. Buy on Amazon
Silvestri, L. A. (2020). Saunders comprehensive review for the NCLEX-RN examination. St. Louis, MO: Elsevier. Buy on Amazon
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