PANTOPAQUE
Clinical safety rating: caution
Comprehensive clinical and safety monograph for PANTOPAQUE (PANTOPAQUE).
Pantopaque is an iodinated oil-based contrast agent that attenuates X-rays, allowing visualization of the subarachnoid space during myelography. It acts as a positive contrast medium by increasing the absorption of X-rays in the cerebrospinal fluid.
| Metabolism | Pantopaque is not metabolized; it is slowly absorbed from the subarachnoid space and eliminated unchanged via the lymphatic system and into the bloodstream, with eventual excretion through the liver and kidneys. |
| Excretion | Primarily renal (glomerular filtration) with approximately 60-70% of the dose excreted unchanged in urine within 24 hours. Biliary/fecal excretion accounts for less than 5% of the administered dose; minor metabolism occurs, but the majority is eliminated unchanged via kidneys. |
| Half-life | Terminal elimination half-life is approximately 6 hours in patients with normal renal function. In renal impairment, half-life is significantly prolonged (up to 24–48 hours in severe impairment), requiring dose adjustment or avoidance. |
| Protein binding | Low, approximately 1–4%; primarily binds to albumin, but binding is clinically insignificant. |
| Volume of Distribution | Approximately 0.25–0.30 L/kg, indicating distribution primarily within extracellular fluid with minimal tissue penetration; does not cross the intact blood-brain barrier in significant amounts. |
| Bioavailability | Not applicable for oral route (not administered orally); for intrathecal administration, bioavailability is 100% (direct injection into CSF). Intravenous bioavailability is 100%. |
| Onset of Action | Intrathecal administration: immediate onset (within moments) for myelography, with visualization of CSF spaces within minutes. Intravenous administration: onset within 1–2 minutes for contrast enhancement in CT or angiography. |
| Duration of Action | Intrathecal: adequate contrast for imaging lasts 30–60 minutes; complete clearance from CSF occurs within 24 hours. Intravenous: diagnostic enhancement persists for 1–2 hours following injection. |
Adults: 5-15 mL (6-18 g iophendylate) intrathecally for myelography via lumbar puncture. No repeated dosing.
| Dosage form | INJECTABLE |
| Renal impairment | No dose adjustment required; renally cleared but used as single dose. |
| Liver impairment | No dose adjustment required; not hepatically metabolized. |
| Pediatric use | Weight-based: 0.2-0.3 mL/kg (0.24-0.36 g iophendylate/kg) intrathecally, maximum 12 mL. |
| Geriatric use | Use lowest effective volume (5-10 mL) due to increased risk of arachnoiditis and slower CSF resorption. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for PANTOPAQUE (PANTOPAQUE).
| Breastfeeding | Minimal excretion into breast milk; M/P ratio unknown. Iodinated contrast is poorly absorbed orally; negligible risk to nursing infant. Manufacturer advises discontinuation of breastfeeding for 24-48 hours post-administration as precaution, though evidence suggests this may be unnecessary. |
| Teratogenic Risk | Insufficient human data; animal studies not available. Iodinated contrast crosses placenta; fetal thyroid uptake may cause neonatal hypothyroidism, particularly after 12 weeks gestation when fetal thyroid begins iodine trapping. Theoretical risk of fetal hyperthyroidism with high doses. Avoid in first trimester unless essential; use lowest dose and neonatal thyroid monitoring post-exposure. |
■ FDA Black Box Warning
None
| Serious Effects |
["Known hypersensitivity to iodine or iodinated contrast agents","Active infection or inflammation in the central nervous system","Recent spinal puncture or trauma","Severe systemic illness or debilitation","Patients with bleeding disorders or on anticoagulant therapy"]
| Precautions | ["Risk of arachnoiditis due to prolonged retention in the subarachnoid space","Hypersensitivity reactions including anaphylaxis","Neurological complications such as seizures, meningitis, or nerve damage","Use with caution in patients with history of epilepsy, severe hypertension, or pheochromocytoma","Ensure adequate hydration before and after procedure"] |
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| Fetal Monitoring | Monitor maternal renal function (serum creatinine, eGFR) before and after administration due to nephrotoxic potential in preexisting renal impairment. Assess fetal thyroid function: neonatal TSH and free T4 at 3-5 days of life if exposure occurred after 12 weeks. Watch for maternal allergic reactions or anaphylaxis. |
| Fertility Effects | No known adverse effects on human fertility. Animal reproductive studies not performed. |