Intracranial delivery of the nitric oxide donor diethylenetriamine/nitric oxide from a controlled-release polymer: toxicity in cynomolgus monkeys.

Abstract

OBJECTIVE:

Diethylenetriamine/nitric oxide (DETA/NO) has been shown to be an effective treatment for delayed posthemorrhagic vasospasm when released abluminally from ethylene-vinyl acetate copolymer (EVAc). However, the observed mortality associated with this drug warrants further investigation. To establish a maximum tolerable dose, this study evaluated the toxicity of DETA/NO released from EVAc in a dose-escalation series in cynomolgus monkeys (Macaca fascicularis).

METHODS:

DETA/NO was incorporated into EVAc at a 20:80 dry weight ratio (DETA/NO:EVAc). A total of 13 animals underwent a right frontotemporal craniotomy for placement of a single polymer delivering no drug (n = 3), 0.5 +/- 0.1 mg/kg (n = 3), 0.9 +/- 0.1 mg/kg (n = 3), 1.9 +/- 0.2 mg/kg (n = 3), or a 3.2 mg/kg dose (n = 1) into the subarachnoid space.

RESULTS:

The animal receiving the highest dose of DETA/NO (3.2 mg/kg) died 46 hours after surgery. The remaining animals survived for the planned duration of the study. One animal in the group receiving the 1.9 mg/kg dose experienced a seizure 25 hours after surgery and remained lethargic for 2 days before making a complete recovery. The remaining animals exhibited no adverse behavioral effects. Histopathological examination of brain tissue revealed hemorrhagic and ischemic changes at doses above 0.9 mg/kg. No evidence of vascular wall pathology or infection was observed in any animal.

CONCLUSION:

The greatest amount of DETA/NO safely delivered from EVAc copolymer to the subarachnoid space of the cynomolgus monkey is approximately 1.0 mg/kg. These findings show that continuous intracisternal delivery of DETA/NO is a safe and potentially effective strategy for prophylactic treatment of delayed cerebral vasospasm.

• Authors: Travis S Tierney, Gustavo Pradilla, Paul P Wang, Richard E Clatterbuck, Rafael J Tamargo
• Journal: Neurosurgery (Neurosurgery) Vol. 58 Issue 5 Pg. 952-60; discussion 952-60 (May 2006) ISSN: 1524-4040 [Electronic] United States
• PMID: 16639332 (Publication Type: Comparative Study, Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• 1-hydroxy-2-oxo-3,3-bis(2-aminoethyl)-1-triazene
• Delayed-Action Preparations
• Nitric Oxide Donors
• Polymers
• Triazenes

Topics

• Animals
• Brain (drug effects)
• Delayed-Action Preparations (administration & dosage)
• Drug Delivery Systems (methods)
• Macaca fascicularis
• Male
• Nitric Oxide Donors (administration & dosage)
• Polymers (administration & dosage)
• Subarachnoid Space (drug effects)
• Triazenes (administration & dosage)