A Nurse Is Preparing To Administer Phenytoin 5 Mg/kg/day

A Nurse Preparing to Administer Phenytoin: A Comprehensive Guide

Phenytoin, a potent anticonvulsant, requires meticulous preparation and administration due to its narrow therapeutic index and potential for adverse effects. This comprehensive guide explores the multifaceted process a nurse undertakes when preparing to administer phenytoin 5mg/kg/day, emphasizing safety, accuracy, and patient well-being.

Understanding Phenytoin and its Administration

Phenytoin (also known as Dilantin) is a hydantoin derivative used primarily to treat seizures and prevent their recurrence. Its mechanism of action involves stabilizing neuronal membranes, reducing the excitability of neurons, and suppressing the spread of epileptic discharges. However, its effectiveness is intricately linked to its plasma concentration; maintaining therapeutic levels is crucial while avoiding toxicity. The dosage of 5mg/kg/day is a common starting point, often adjusted based on individual patient response and therapeutic drug monitoring (TDM).

Crucial Considerations Before Administration

Before administering any medication, particularly a drug like phenytoin, a nurse must follow a rigorous checklist:

Verify the Doctor's Order: Double-checking the prescription for accuracy – dose, frequency, route, and patient identification – is paramount. Any discrepancies should be immediately clarified with the prescribing physician.
Patient Identification: Utilize two patient identifiers (e.g., name and date of birth) to confirm the correct patient before administering any medication. This critical step helps prevent medication errors.
Allergies and Medication History: A thorough review of the patient's medical history, including allergies and current medications, is essential. Phenytoin interactions with other drugs can significantly impact efficacy and safety. For example, concurrent use with certain antibiotics or anticoagulants may alter phenytoin metabolism and necessitate dose adjustments.
Assessment of Patient Condition: Before administering phenytoin, the nurse should assess the patient's vital signs (heart rate, blood pressure, respiratory rate), level of consciousness, and any existing neurological symptoms. This baseline assessment allows for comparison post-administration and detection of potential adverse reactions.
Preparation of the Medication: The specific preparation method depends on the formulation (e.g., intravenous, oral). Intravenous phenytoin requires special attention due to its potential for causing vein irritation and cardiac complications. Oral administration demands careful consideration of the patient's ability to swallow and potential for medication interactions with food.

Calculating the Phenytoin Dose

Accurately calculating the dose is crucial. The order is 5mg/kg/day. This calculation requires the patient's weight in kilograms.

Example:

Let's assume the patient weighs 70kg.

Step 1: Convert the weight to kilograms (if necessary). In this case, it's already in kilograms.
Step 2: Calculate the daily dose: 5mg/kg/day * 70kg = 350mg/day
Step 3: Determine the frequency of administration based on the physician's order. The daily dose might be given in one dose, divided into two doses, or even three smaller doses depending on the patient's needs and the preparation chosen. For example, 350mg/day might be given as two 175mg doses, once every 12 hours.

Important Note: Always double-check the calculations with a colleague before administering the medication. Medication errors can have severe consequences.

Administering Phenytoin: Intravenous vs. Oral

The method of administration significantly impacts the preparation and nursing considerations.

Intravenous (IV) Administration of Phenytoin

IV administration requires specialized knowledge and strict adherence to protocols. The following points are critical:

Compatibility: Phenytoin is incompatible with many intravenous solutions. Consult a drug compatibility chart before mixing. Typically, it is administered through a dedicated IV line.
Rate of Infusion: Fast administration can lead to cardiac arrhythmias. The medication should be infused slowly, at a maximum rate of 50mg per minute. Close monitoring of the patient's ECG is essential during and after the infusion.
Dilution: Phenytoin for IV administration needs to be diluted appropriately. The concentration should be carefully checked to avoid precipitation and ensure proper delivery.
Monitoring for Adverse Effects: Close monitoring for hypotension, bradycardia, and other cardiovascular complications is mandatory during and after IV administration.

Oral Administration of Phenytoin

Oral administration, while simpler than IV administration, also necessitates careful attention to detail.

Absorption: Phenytoin absorption can be affected by food intake. Following the physician's instructions regarding administration with or without food is vital.
Extended-Release Preparations: If an extended-release formulation is prescribed, it should not be crushed or broken. This can lead to unpredictable drug release and increased risk of side effects.
Monitoring for Side Effects: Regular monitoring for gingival hyperplasia (gum overgrowth), which is a common side effect of long-term phenytoin use, is important. Other potential side effects include nystagmus, ataxia, and cognitive impairment.

Post-Administration Monitoring and Nursing Considerations

After administering phenytoin, the nurse's responsibilities continue.

Vital Signs: Close monitoring of vital signs (heart rate, blood pressure, respiratory rate) is crucial to detect any adverse reactions promptly.
Neurological Assessment: Observe the patient for signs of neurological changes such as drowsiness, dizziness, confusion, or seizures.
Therapeutic Drug Monitoring (TDM): Blood samples are usually taken to monitor the plasma concentration of phenytoin. This helps ensure that the medication is within the therapeutic range (typically 10-20 mcg/mL) and that the dose is adjusted accordingly to maximize therapeutic benefit while minimizing toxicity.
Patient Education: Provide clear and concise patient education regarding medication administration, potential side effects, and the importance of regular follow-up appointments.
Documentation: Accurate and complete documentation of medication administration, including the dose, route, time, and any observed side effects, is essential.

Addressing Potential Complications and Adverse Effects

Phenytoin, like many medications, can cause adverse effects. Prompt recognition and appropriate interventions are crucial.

Cardiovascular effects: Hypotension, bradycardia, and cardiac arrhythmias are potential cardiovascular complications, especially with IV administration. Careful monitoring and prompt intervention are essential.
Neurological effects: Drowsiness, dizziness, ataxia, nystagmus, and cognitive impairment are common neurological side effects. Dose adjustment or alternative medications may be necessary.
Skin reactions: Skin rashes, including Stevens-Johnson syndrome, are rare but serious side effects. The medication should be stopped immediately if a skin rash develops.
Gingival hyperplasia: This is a common side effect of long-term phenytoin use, characterized by gum overgrowth. Good oral hygiene and regular dental check-ups can help manage this complication.
Hepatotoxicity: Rarely, phenytoin can cause liver damage. Liver function tests should be monitored regularly.
Blood dyscrasias: Phenytoin can affect blood cell production, leading to anemia, leukopenia, or thrombocytopenia. Blood counts should be monitored regularly.
Interactions with other medications: Phenytoin interacts with many other drugs, potentially altering their metabolism and efficacy. Careful consideration of potential drug interactions is essential.

Conclusion

Administering phenytoin requires a high level of nursing competence, attention to detail, and a strong understanding of the medication's properties and potential adverse effects. By following strict protocols, accurately calculating dosages, meticulously monitoring the patient, and promptly addressing any complications, nurses can ensure safe and effective phenytoin therapy, contributing significantly to patient well-being and seizure control. Continuous professional development and staying updated on the latest guidelines are essential for optimal patient care. This comprehensive guide emphasizes the importance of proactive safety measures and patient-centered care, ultimately fostering the best possible outcomes for individuals receiving phenytoin. Remember, always consult the latest drug information resources and institutional protocols for the most up-to-date and accurate guidelines.