Placidyl Information Distributed by Abbot Laboratories to Physicians, Circa 1971:

Patients who are taking PLACIDYL or other [central nervous system]-acting drugs should be cautioned about the possible combined exaggerated effects with alcohol, barbiturates, tranquilizers or other central nervous system depressants [that] might result in blurring of vision, paralysis of accommodation and profound hypnosis.

Patients also should be cautioned concerning driving a motor vehicle, operating machinery, or other hazardous operations requiring alertness shortly after taking PLACIDYL.

PLACIDYL should be administered with caution [to] patients with suicidal tendencies and large quantities of the drug should not be prescribed.

Psychological and Physical Dependence: PLACIDYL, LIKE OTHER SEDATIVE-HYPNOTIC DRUGS, HAS THE POTENTIAL. … FOR THE DEVELOPMENT OF PSYCHOLOGICAL AND PHYSICAL DEPENDENCE. INSTANCES OF SEVERE WITHDRAWAL SYMPTOMS, INCLUDING CONVULSIONS AND [DELIRIUM] CLINICALLY SIMILAR TO THOSE SEEN WITH BARBITURATES, HAVE BEEN REPORTED IN PATIENTS TAKING REGULAR DOSES AS LOW AS 1000 MG. PER DAY OVER A PERIOD OF TIME WHEN THE DRUG WAS SUDDENLY DISCONTINUED. [Capitals in original.]

In view of the potential of PLACIDYL (ethchlorvynol) for inducing dependence, prolonged administration of the drug is not recommended.

Patients, particularly those known to be addiction-prone, or those who are likely to increase dosage Of PLACIDYL on their own initiative, should be observed for evidence of signs or symptoms which may indicate possible early withdrawal or abstinence symptoms. Signs and symptoms associated with withdrawal and abstinence include unusual anxiety, tremor, ataxia [muscular incoordination], slurring of speech, memory loss, perceptual distortions, irritability, agitation and delirium. Other less well defined signs and symptoms, not necessarily due to withdrawal and abstinence [,] may include anorexia, nausea, or vomiting, weakness, dizziness, sweating, muscle twitching and weight loss. Abrupt discontinuance Of PLACIDYL following prolonged overdosage may result in convulsions and [delirium].

Treatment of a patient who manifests withdrawal symptoms from PLACIDYL abuse involves readministration of the drug to approximate the same level of chronic intoxication which existed before the abrupt discontinuance. … A gradual, stepwise reduction of dosage may then be made over a period of days or weeks. The patient must be hospitalized or closely observed and gives general supportive care as indicated.

PRECAUTIONS: … Patients who respond unpredictably to barbiturates or alcohol, or who exhibit excitement and release of inhibitions in association with such agents may also react in this way to PLACIDYL.

Rarely, patients may exhibit symptoms suggestive of an unusual susceptibility to the drug: prolonged hypnosis, profound muscular weakness, excitement, hysteria, or syncope [fainting] without marked hypotension.

In occasional patients the drug appears to be absorbed very rapidly and may produce transient giddiness or ataxia. Should this occur, a glass of milk or other food should be given with subsequent doses of the drug, or the drug discontinued.

ADVERSE REACTIONS: Hypotension [low blood pressure], nausea or vomiting, gastric upset, aftertaste, blurring of vision, dizziness, facial numbness, and allergic reaction typified by urticaria [hives] have been reported following PLACIDYL (ethchlorvynol) administration. Mild "hangover" and symptoms of mild excitation have occurred in some patients. …