Bupivacaine
Bupivacaine. Long-acting amide local anesthetic — Na+ channel blocker with ~4× duration of lidocaine. Used for epidurals, spinal… Subcutaneous half-life 1.8 h.
Long-acting amide local anesthetic — Na+ channel blocker with ~4× duration of lidocaine. Used for epidurals, spinal anesthesia, nerve blocks. Cardiotoxicity (intractable VT/VF on accidental IV injection) is the dose-limiting concern; lipid emulsion is the rescue therapy.
PK: KEEP THE PLASMA CURVE — THIS IS NOT A LOCAL-ACTING RECORD — BUT THE ROUTES WERE WRONG AND THE CITATION WAS AN INTRAVENOUS STUDY. Two sibling records were stripped to local-acting in this same batch on the grounds that plasma concentration is not what drives effect; bupivacaine differs, and its own citation says why: "All subjects experienced mild CNS toxicity ... associated with peak venous plasma concentrations of 0.81 to 2.7 micrograms/ml". That is a dose-limiting, CONCENTRATION-DEFINED toxicity, which is exactly what a plasma curve is for, and stripping the record would delete the only quantitative safety signal in it. What was broken is the route declaration: it listed intramuscular, subcutaneous and transdermal with parameters on the intramuscular one, AND BUPIVACAINE HAS NO INTRAMUSCULAR AND NO TRANSDERMAL PRODUCT — its own mechanism text says epidural, spinal and nerve block. That paper administered the drug INTRAVENOUSLY, so the row was also a route mismatch. THE VOCABULARY HAS NO EPIDURAL OR INTRATHECAL ROUTE, so the record still cannot be filed exactly right; subcutaneous is kept because infiltration block genuinely is subcutaneous, and the values move to a real human epidural dataset. TWO CAUTIONS ARE RECORDED: that source reports lidocaine and bupivacaine as PAIRS in every sentence and the FIRST value is lidocaine, and its population is parturients, whose free fraction is higher. The row over-predicts exposure about 15% by construction, being below the one-compartment floor. ITS OCCUPANCY ROW IS IN THE WRONG COMPARTMENT: the affinity is a frog sciatic nerve block, and at therapeutic plasma levels it reads about ten percent, which is neither the anaesthetic effect at the nerve nor a calibrated cardiotoxicity metric.
Pharmacokinetics
- Subcutaneous — t½ 1.8 h · F 100% · ka 3.8 h⁻¹ · Vd 117 L
Sources: PMID:3800032, PMID:8368546, PMID:9768788, PMID:2024561, PMID:9052295