ON THE SUBJECT OF INTRA-THECAL PHARMACEUTICALS…
Over the years, I’ve received numerous calls and questions regarding the chemical characteristics of intra-thecal medications. In answer to these queries, I’ve decided to get the ball rolling by sharing some published information with you – on solubility and syringe composition limits – information that I believe will prove of some value.
Maximum Solubility of Common Intraspinal Drugs at Room Temperature (21° C):
Baclofen: 5.0 mg/ml
Bupivacaine HCL: 40.0 mg/ml
Clonidine HCL: 76.0 mg/ml
Fentanyl Citrate: 25.0 mg/ml
Hydromorphone HCL: 250.0 mg/ml
Morphine Sulf.: 64.5 mg/ml
Sufentanil Citrate: 25.0 mg/ml
As most of you out there are aware, the drugs noted above are maintained in the pump’s reservoir at 37° C. Solubility of IT meds is affected by additional drugs contained within the mixture.
OUR TAKE: Poly pharmaceutical solutions will interact and thereby alter certain chemical states of the combined drugs. For that reason, we do not recommend maximizing the drug concentration when used in combination with other agents.
Obviously, the maximum concentrations of these pharmaceuticals exceed clinical applications. The chart below shows the lipid solubility and equal analgesic conversions when drug alternation is required. Please keep in mind, this is a guide – and that thorough understanding of each drug is necessary prior to dosage change.
Intra-thecal Analgesic Properties / Dosing Conversions
| Drug |
Opioid Solubility |
Equal Analgesic Dosing (mg) |
| Morphine |
1 |
1 |
| Hydromorphone |
1.4 |
0.25 |
| Fentanyl Cit |
580 |
0.01 |
| Sufentanil Cit |
1270 |
0.001 |
Questions? We’re happy to address them. Just contact me at wstuart@hartleymedical.com or call our office at 562.595.7548.