Accurately converting amlodipine dosage from oral to intravenous administration requires careful attention to individual patient characteristics. Dosage adjustments are frequently necessary.
Hepatic Function
Patients with impaired liver function metabolize amlodipine slower. Therefore, reduce the IV dose to avoid amlodipine accumulation and potential toxicity. Consider a reduction of 50% or more depending on the severity of hepatic impairment, as determined by Child-Pugh score. Always consult liver function tests (LFTs) before initiating IV amlodipine.
Renal Function
Renal excretion plays a significant role in amlodipine elimination. Compromised kidney function necessitates dose adjustment. Creatinine clearance (CrCl) is the key indicator. Use a validated formula like the Cockcroft-Gault equation to estimate CrCl. Lower CrCl values necessitate lower amlodipine doses. Consult renal function tests before administration.
Age and Body Weight
- Age: Older adults (≥65 years) often exhibit reduced clearance of amlodipine, necessitating a lower initial dose. Body weight: While not as significant as hepatic and renal function, body weight can influence drug distribution. Consider this when determining the appropriate dose for notably heavier or lighter individuals.
Concomitant Medications
Certain medications interact with amlodipine, potentially altering its metabolism and efficacy. Examples include strong CYP3A4 inhibitors (e. g., ketoconazole, ritonavir) and inducers (e. g., rifampin). Review the patient’s medication history thoroughly to identify potential drug interactions and adjust the amlodipine dose accordingly. Consult drug interaction databases.
Underlying Conditions
Heart failure: Patients with heart failure may require careful titration of amlodipine IV to avoid excessive hypotension. Hypertension: Severely hypertensive patients might necessitate slower titration to prevent a sudden drop in blood pressure.
Monitoring
Continuous monitoring of blood pressure and heart rate is paramount during IV amlodipine administration. Regularly assess for adverse effects such as hypotension, edema, and dizziness. Adjust the dosage based on the patient’s response.
