LD50 values

The LD50 values of carisoprodol for rats are 450 mg/kg for intravenous (IV) and intraperitoneal injection, and 1,320 mg/kg for gavage dosing. In mice, the LD50 values are 165 mg/kg for intravenous injection, 980 mg/kg for intraperitoneal injection, and 2,340 mg/kg for gavage dosing. The LD50 value for rabbits given carisoprodol by intravenous injection is 124 mg/kg ^F4078.

Overdose

An overdose of carisoprodol leads to CNS depression, and in severe cases, induction of a coma. Shock, depression of respiratory function, seizures and death have also been reported in rare cases. Several symptoms may be associated with carisoprodol overdose, such as horizontal and vertical nystagmus, blurred vision, mydriasis, mild tachycardia and hypotension, respiratory depression, euphoria, CNS stimulation, muscular incoordination, and/or rigidity, confusion, headache, hallucinations, and dystonic reactions. Alcohol or other CNS depressants or psychotropic agents can exert additive effects on carisoprodol even when one of the agents has been ingested at the normal, therapeutic dose. Fatal accidental and non-accidental overdoses have both been reported with carisoprodol ingestion alone or ingestion of carisoprodol in combination with alcohol or psychotropic drugs ^F4057.

A note on dependence and withdrawal

In the postmarketing reports after carisoprodol use, cases of dependence, withdrawal, and abuse have been reported with long-term use. The majority of dependence and withdrawal cases, as well as abuse, have occurred in patients with a history of addiction or who have used this drug in combination with other drugs having abuse potential. However, multiple post-marketing adverse event reports have been made of carisodopril-associated abuse when used without other drugs possessing abuse potential. Withdrawal symptoms have been observed and reported following sudden abrupt cessation after long-term carisodoprol use. To reduce the chance of carisodopril dependence, withdrawal, or abuse, carisodopril should be used with caution in addiction-prone patients and in patients taking other CNS depressants including alcohol. This drug should not be taken for longer than 2 to 3 weeks for symptomatic relief of acute musculoskeletal discomfort ^{FDA label}.

Use in pregnancy

This drug has been classified as Pregnancy Category C. There are no clinical trial data on the use of carisoprodol during human pregnancy. Animal studies show that carisoprodol crosses the placenta and leads to adverse effects on fetal growth and postnatal survival. In postmarketing reports, the main metabolite, meprobamate, has not demonstrated a consistent association between maternal use and an increased risk for specific congenital malformations ^{FDA label}.

Use in nursing

Limited data in humans demonstrate that this is found excreted in breast milk and may reach concentrations in breast milk of 2-4 times the maternal plasma concentrations ^{FDA label}. It is therefore advisable to exercise caution when this drug is used during breastfeeding ^{FDA label}.