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Linctuses: Monophasic Liquid Dosage Form

 LINCTUSES

What is a Linctus?

  • Linctuses are sweet, viscous liquid oral preparations containing medicinal substances which have demulscent, expectorant or sedative properties.
  • These contain high proportions of syrup and glycerin which exert demulscent effect on the mucous membrane of throat.
  • In order to obtain prolonged local action, linctuses should be administered slowly in undiluted form.

Formulation of Linctus

 1. Vehicle:

  • Syrups are mostly used as vehicles in the linctuses.
  • Tolu syrup is preferred in cough preparations due to its aromatic odor and flavour.
  • Glycerol syrup and invert syrup are also used as vehicles.
  • Linctus preparation for diabetic patients contain sorbitol syrup (vehicle).
  • Medicament is first dissolved in little amount of water and then added into vehicle. Syrups are viscous and contain less amount of water, this limits (affects) the dissolution of medicament in syrup.

2. Additives:

  • Colouring agents: Amaranth, Erythrosin, Tartrazine.
  • Flavouring agents: Lemon syrup, black currant syrup.
  • Preservatives: Chloroform spirit, Benzoic acid.

Preparation of Linctuses

Medicament is dissolved in water then additives are added with continuous agitation. In this mixture syrup is slowly added up to the mark.


Instruction for administration:

To be sipped and swallowed slowly without adding water.

EXAMPLE:

Ammonium chloride linctus (ammonium chloride, chlorpheniramine maleate, sodium citrate, compound tartrazine and syrup)



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