Linctuses, Syrups and Elixirs: The Practical

Three sweet liquids

All three are oral liquids and are measured with a 5 mL spoon or an oral syringe.

Linctuses

A linctus is thick and sweet so that it coats the throat and soothes it. The patient takes it in small sips.

Practical points:

• Do not dilute a linctus. Dilution makes it thin and ruins its soothing action.
• Do not drink water straight after the dose, as it washes the coating away.
• The usual dose is 5 mL, taken slowly. The dose for children depends on age, so follow the prescription.
• A linctus is a symptom reliever. A cough that lasts more than a few days needs a doctor.
• Some linctuses contain drugs that cause drowsiness, so the label may warn the patient not to drive.

Syrups

A syrup is a concentrated solution of sugar (sucrose) in water. The sugar:

• makes the preparation sweet and pleasant;
• makes it thick;
• resists germs, because the concentrated sugar holds the water tightly so germs cannot grow.

A plain syrup with no drug is the base for many medicated syrups and is called simple syrup. Many commercial syrups use other sweeteners instead of sugar. A sugar-free syrup is thickened with other agents, so check the label.

Why dilution matters

If a syrup is diluted, the sugar becomes weaker and germs can grow. A diluted syrup should be freshly prepared, kept for a short time, and given a short discard date. A dilution is also a new product, so it should be done only on the pharmacist's instruction and with a suitable diluent.

Elixirs

An elixir is a clear, sweetened and flavoured liquid. Its vehicle contains alcohol and water. The alcohol helps dissolve drugs that dissolve poorly in water alone.

Practical points:

• Elixirs are clear. If one turns cloudy, an ingredient has come out of solution, so tell the pharmacist.
• Do not dilute an elixir with too much water without advice, as the drug may come out of solution.
• The alcohol content matters for children, for people who avoid alcohol for health or religious reasons, and for people taking medicines that react with alcohol. Always check the label and advise the patient.

Handling thick liquids

• Pour slowly, to avoid air bubbles and spills.
• Allow extra time for the liquid to drain from the measure. Otherwise some stays behind and the dose is short.
• Wipe the neck of the bottle so the closure does not stick.
• Use measuring spoons or oral syringes supplied with the medicine. Kitchen spoons vary in size.
• Keep the cap tight, and store as the label says.

Worked examples

Dose volume. A syrup contains 125 mg in 5 mL. The dose is 250 mg.

• Volume = 250 ÷ 125 × 5 = 10 mL

Volume to supply. The dose is 5 mL four times a day for 5 days.

• 5 × 4 × 5 = 100 mL

Alcohol in a dose. An elixir contains 10% v/v alcohol. The dose is 5 mL.

• 5 × 10 ÷ 100 = 0.5 mL of alcohol per dose

Doses in a bottle. A bottle holds 100 mL and the dose is 5 mL.

• 100 ÷ 5 = 20 doses

Labelling and advice

Label each preparation with the patient's name, the directions, the date and the discard date, and add advice that suits it:

Also tell the patient to keep the bottle tightly closed, away from children, and to finish the course if it is an antibiotic.

Safety and records

• Check the name and strength on the bottle, and compare it with the prescription.
• Check the expiry date and the discard date of any opened bottle.
• Record any dilution, with the diluent, the amount and the discard date.
• Do not give a syrup that has crystals, mould or a changed smell. Tell the pharmacist.