Many analgesics are excreted by the kidneys and any degree of renal impairment can reduce drug clearance, and therefore the dose of drug required. Glomerular filtration rate (GFR) gives an indication of how much drug clearance will be affected by renal impairment. Renal dysfunction can also influence the absorption, metabolism, distribution and pharmacodynamics of many drugs.
End Stage Renal Disease (ESRD) correlates to:
- GFR of less than 15mL/min or
- Stage 5 (UK CKD Guidelines 2005)
Patients with GFR 15-29mls/min (Stage 4) will also be more safely managed with medication dose reductions recommended for Stage 5 disease.
In general when prescribing analgesics in ESRD:
- immediate release preparations are safer than sustained/ modified/ controlled release preparations
- p.r.n. (as required) prescriptions are safer than regular prescriptions
- extended dose intervals are better tolerated