Current Scheduling Status
None
Year(s) and type of review / ECDD meetings
Drug Class
Recommendation (from TRS)
Substance identification
Proxibarbal (INN, CAS-2537-29-3), chemically 5-allyl-5-(2-hydroxypropyl)barbituric acid, is also known as vasalgin. It is a racemic mixture.
Similarity to known substances and effects on the CNS
The pharmacological profile of proxibarbal differs from that of the classical barbiturates. The hydroxyl side-chain is reported to decrease lipid solubility and abolish hy pnotic activity. In human performance tests, proxibarbal did not impair the subjects’ ability to discriminate, nor did it prolong the reaction time; also, no effect on the potentiation of the effects of alcohol was demonstrated. It is metabolized to the corresponding lactone, valofane, or alphaallophanyl-alpha-allyl-gamma-valerolactone. Proxibarbal is not similar to any of the already scheduled substances. In subchronic, chronic, and toxicological studies, proxibarbal did not reveal any unusual toxicity and was well tolerated. Slight drowsiness or dizziness were the main symptoms observed in some patients. It has no hypnotic effects.
Dependence potential
In rhesus. monkeys, proxibarbal did not induce physical dependence. Valofane (proxibarbal’s transformation product) did not appear to possess reinforcing properties in rhesus monkeys
administering the drug intravenously.
Actual abuse and or/evidence of likelihood of abuse
There are no data available on abuse, except for reports of isolated cases of abuse from Austria. It is under national control in six countries.
Therapeutic usefulness
Proxibarbal is used for long-term treatment of migraine and other types of vascular headache. It is also recommended in menopausal symptoms, especially for headaches and hot flushes and other premenstrual symptoms. It is approved for marketing in sixteen countries but is available only in twelve. The volume of production is large. The Committee rated the therapeutic usefulness of proxibarbal as moderate.
Recommendation
The Committee found that there was insufficient evidence that
proxibarbal is being, or is likely to be, abused so as to constitute a
public health and social problem warranting the placing of the
substance under international control. ~
On the basis of the data concerning its pharmacological profile, dependence potential, and actual abuse, the Committee rated the likelihood of abuse of propallylonal as low. The degree of the public health and social problems associated with the drug was also found to be low and its therapeutic usefulness moderate. In the light of this assessment, the Committee recommended against scheduling of the drug.
Proxibarbal (INN, CAS-2537-29-3), chemically 5-allyl-5-(2-hydroxypropyl)barbituric acid, is also known as vasalgin. It is a racemic mixture.
Similarity to known substances and effects on the CNS
The pharmacological profile of proxibarbal differs from that of the classical barbiturates. The hydroxyl side-chain is reported to decrease lipid solubility and abolish hy pnotic activity. In human performance tests, proxibarbal did not impair the subjects’ ability to discriminate, nor did it prolong the reaction time; also, no effect on the potentiation of the effects of alcohol was demonstrated. It is metabolized to the corresponding lactone, valofane, or alphaallophanyl-alpha-allyl-gamma-valerolactone. Proxibarbal is not similar to any of the already scheduled substances. In subchronic, chronic, and toxicological studies, proxibarbal did not reveal any unusual toxicity and was well tolerated. Slight drowsiness or dizziness were the main symptoms observed in some patients. It has no hypnotic effects.
Dependence potential
In rhesus. monkeys, proxibarbal did not induce physical dependence. Valofane (proxibarbal’s transformation product) did not appear to possess reinforcing properties in rhesus monkeys
administering the drug intravenously.
Actual abuse and or/evidence of likelihood of abuse
There are no data available on abuse, except for reports of isolated cases of abuse from Austria. It is under national control in six countries.
Therapeutic usefulness
Proxibarbal is used for long-term treatment of migraine and other types of vascular headache. It is also recommended in menopausal symptoms, especially for headaches and hot flushes and other premenstrual symptoms. It is approved for marketing in sixteen countries but is available only in twelve. The volume of production is large. The Committee rated the therapeutic usefulness of proxibarbal as moderate.
Recommendation
The Committee found that there was insufficient evidence that
proxibarbal is being, or is likely to be, abused so as to constitute a
public health and social problem warranting the placing of the
substance under international control. ~
On the basis of the data concerning its pharmacological profile, dependence potential, and actual abuse, the Committee rated the likelihood of abuse of propallylonal as low. The degree of the public health and social problems associated with the drug was also found to be low and its therapeutic usefulness moderate. In the light of this assessment, the Committee recommended against scheduling of the drug.
ECDD Recommendation
Scheduling/control not currently recommended
Link to full TRS
who_trs_741.pdf2.21 MB