Can I use paracetamol (acetaminophen) with hyoscine (scopolamine) for an adult patient with a history of kidney stones and no impaired renal function?

Yes, paracetamol and hyoscine can be used together in patients with normal renal function

In patients without renal impairment, paracetamol (acetaminophen) and hyoscine can be safely combined, as there are no documented drug-drug interactions between these medications and both are considered appropriate analgesic/antispasmodic options in this clinical context. 1

Paracetamol Safety in Normal Renal Function

• Paracetamol is the analgesic of choice in patients with normal renal function and does not require dose adjustment even when clearance is slightly reduced. 2
• The standard adult dosing is 1000 mg per dose, with a maximum daily dose of 4000 mg (or 3000 mg for chronic use to minimize hepatotoxicity risk). 3
• Regular paracetamol administration should be prescribed routinely for pain management unless specifically contraindicated. 1

Hyoscine Considerations

• Hyoscine (hyoscine butylbromide/Buscopan) is an antimuscarinic agent commonly used for smooth muscle spasm, which is particularly relevant in the context of kidney stones. 4
• While one case report documented acute kidney injury with a medazepam-hyoscine combination in an elderly patient with hepatitis C, this was in the context of polypharmacy and advanced age, not in patients with normal baseline renal function. 5
• In patients with normal renal function, hyoscine does not carry specific contraindications related to kidney function. 4

Specific Context: Kidney Stones Without Renal Impairment

• For patients with kidney stones (renal colic) and normal renal function, both medications are appropriate choices. 4
• NSAIDs should be avoided or used with extreme caution in patients with any degree of renal dysfunction, making paracetamol the preferred analgesic. 1
• Approximately 40% of hip fracture patients present with at least moderate renal dysfunction, highlighting the importance of verifying normal renal function before medication selection. 1

Important Caveats

• Always verify actual renal function with urea and electrolyte biochemistry results before finalizing the analgesic regimen. 1
• Paracetamol nephrotoxicity can occur with overdose even in the absence of hepatotoxicity, so adherence to maximum dosing limits is critical. 6, 7
• The combination carries no documented drug-drug interaction risk, unlike combinations involving opioids with benzodiazepines or gabapentinoids, which should be avoided. 1