Premedication

Premedication refers to a drug treatment given to a patient prior to a surgical or invasive medical procedure, to obtain anxiolysis. These drugs are typically sedatives. However, premedications can also be used on occasion for other reasons, such as reducing salivary and bronchial secretions, lessening the response to painful stimuli and reducing the risk of vomiting, particularly prior to general anaesthesia.

When considering the management of anxious patients under conscious sedation, premedication is used for producing pre‐operative anxiolysis and is generally given by the oral route. Such premedication may be indicated in the following cases:

• To reduce anxiety the night before the appointment
• To reduce anxiety in the 1–2 hour period before treatment
• For patients who are needle phobic, but require intravenous sedation for treatment.

Drugs Used for Pre‐operative Anxiolysis

Several agents can be used for premedication but the benzodiazepines are the most commonly used.

Diazepam

Until recently, diazepam was the most commonly and widely used of all sedatives for premedication. It is available in tablets of 2 mg, 5 mg and 10 mg and is fairly reliably absorbed from the gut, its effects becoming apparent after about 30 minutes. The correct dosage for each individual is not easy to calculate, since several factors influence its action. In particular, it does appear to bear a relationship to the age of a patient, much higher (relative) dosages being required in children and adolescents. As with intravenous administration, the converse is true in the elderly and infirm. As a rough guide, for adults, a dose between 0.1 mg and 0.25 mg/kg of body weight will produce adequate anxiolysis and should be given 1 hour before surgery and after a light snack. Administration of a single dose of oral diazepam, does give the operator the opportunity to form a baseline assessment, on which further action may be taken. Too high a dosage will cause sleep, while inadequate dosage will result in an alert and still anxious patient. Potential side effects include dizziness, increased pain awareness, ataxia (difficulty maintaining posture) and occasional respiratory depression. Prolonged post‐operative drowsiness has also been reported.

Caution is necessary in administering diazepam to patients with obvious psychoses, neuromuscular disorders, or respiratory, liver or kidney disease. Alcohol intake must be prohibited for a period of 24 hours before and after administration. Patients should not drive or operate machinery for 24 hours post‐medication. As with intravenous diazepam, there is also a slight risk of some re‐sedation after 2–3 days due to the production of active metabolites.

Temazepam