Density matters most.
Wildsmith
J A W
JA
D000775:Anesthesia, Spinal / Q000379:methods; D000779:Anesthetics, Local / Q000493:pharmacokinetics*; D002045:Bupivacaine / Q000031:analogs & derivatives / Q000493:pharmacokinetics*; D002626:Chemistry, Pharmaceutical; D006801:Humans; D000077554:Levobupivacaine; D011187:Posture / Q000502:physiology; D013046:Specific Gravity
D000779:Anesthetics, Local; D000077554:Levobupivacaine; D002045:Bupivacaine