Overview Of Pharmaceutical Lozenges And Trouches

Lozenges are solid preparations that are intended to dissolve or disintegrate slowly in the mouth. They are flavored medicated dosage forms intended to be sucked and held in the mouth or pharynx. They contain one or more medications usually in a flavored, sweetened base. Lozenges are most often used for localized effects in the mouth. They can also be used for systemic effect if the drug is well absorbed through the buccal lining or is swallowed.

Lozenges and Trouches

Advantages Of Lozenges And Trouches

1. Being easy to administer to pediatric and geriatric patients.

2. Having formulas that are easy to change and can be patient specific

3. Keeping the drug in contact with the oral cavity for an extended period of time

4. Pleasant taste

5. It extends the time of drug in the oral cavity to elicit a specific effect

6. Easy to prepare, with minimum amount of equipment and time

7. Do not require water intake for administration

8. Technique is non invasive, as is the case with parenterals, hence painless

9. They are economical and safe to the patient

10. Self administration is possible

11. Their toxicity is delayed due to the onset of action which permits easier recovery than in case of other dosage forms

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Disadvantages Of Lozenges And Trouches

1. Children may think it is candy

2. Not suitable for patient with nausea and vomiting, unconscious patient

3. Drugs destroyed by gastric enzyme will not survive

4. Drug variability between different dose and patient due to different sucking patterns

Classification Of Lozenges And Trouches

There are different classifications of lozenges. They are;

a. According to site if action: local and systemic

b. According to texture and composition:

i. Chewy or Caramel Based Medicated Lozenges

Ii. Compressed tablet lozenges

iii. Soft Lozenges

iv. Hard Candy Lozenges

Lozenges can be made by molding (pastilles) or by compression (trouches). Commercial lozenges are made by compression. Compounded lozenges can be prepared by molding mixtures of ingredients containing: sugars to form a hard lozenge, polyethylene glycol (PEG) to form a soft lozenge and gelatin to form a chewable lozenge.

Chewy or Caramel Based Medicated Lozenges

Chewy or caramel based medicated lozenges are the dosage form in which medicament is incorporated into a caramel base which is chewed instead of being dissolved in mouth. Most formulations are based on the glycerinated gelatin suppository formula which consists of glycerin, gelatin, and water. These lozenges are often highly fruit flavored and may have a slightly acidic taste to cover the acrid taste of the glycerin Its constituent ingredients are the candy base, whipping agent, humectants, lubricants, flavor and of course medicaments incorporated into the lozenges. The candy base consists of a mixture of sugar and corn syrup in a ratio of 50:50 to 75:25 sugar to corn syrup. Medicaments up to 35- 40% can be incorporated.

These lozenges are often highly fruit flavored and may have a slightly acidic taste to cover the acrid taste of the glycerin. Most formulations are based on the glycerinated gelatin suppository formula which consists of glycerin, gelatin, and water. Another method is to buy gummy candy, melt it with little heat and add the drug. The resulting mixture is cooled.

Compressed Tablet Lozenges (Trouches)

The lozenge is made using heavy compression equipment to make a tablet that is harder than usual, as it is desirable for the troche to dissolve slowly in the mouth. They are usually flat faced with sizes, weight, hardness, and erosion time ranging between, 5/8-3/4 inch, 1.5-4 g, 30-50 kg inch2 and 5-10 min, respectively. The ingredients for compressed tablet lozenges are tablet based or vehicles which are sugar such as dextrose, sucrose. Other vehicles are sugar free vehicles such as mannitol, sorbitol, polyethylene glycol (PEG) 6000 and 8000. Excipients include binders, colours and lubricants. The key difference between a troche and a standard pill is the way they’re processed by the body. A trouches bypasses the gastric enzyme. Essentially, lozenge tablets differ from conventional tablets only in their organoleptic and non-disintegrating properties and slower dissolution rate.

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Soft Lozenges

Soft lozenges are easily compounded and can be colored and flavored. They can either be chewed or allowed to slowly dissolve in the mouth. They are typically made of ingredients such as polyethylene glycol (PEG) 1000 or 1450, chocolate, or a sugar-acacia base. These are mixtures of sugar and other carbohydrates in an amorphous (non crystalline) or glassy state. They can also be regarded as solid syrups of sugars. The moisture content and weight of hard candy lozenge should be in between, 0.5 - 1.5% and 1.5-4.5 g respectively. These should undergo a slow and uniform dissolution or erosion over 5 - 10 minutes and they should not disintegrate. Suitable for only heat resistant drugs.

Hard Lozenges

These dosage forms are made by heating sugars and other ingredients together and then pouring the mixture into a mold. The molds can shape the mixture to look like a sucker or a lollipop. The hard lozenge will not disintegrate in the mouth but will erode or dissolve over a 5 - 10 minutes period. The dosage form needs a low moisture content (0.5 - 1.5%) so water is evaporated off by boiling the sugar mixture during the compounding process. The weight should be between 1.5-4.5g. The sugar content should be 55 - 65% sucrose and about 35 - 45% corn syrup. Medicaments up to 2-4% can be incorporated.

Read Also: Difference Between Dry Granulation And Direct Compression

Other ingredients include sweetening agents, acidulants, colours and flavours. Disadvantages of this form is that heat labile drugs cannot be used in this formulation because of the high temperatures required for preparation. Also, hard lozenges become grainy.

Note On Lozenges

A soft variety of lozenge, called a pastille, consists of medicament in a gelatin or glycero- gelatin or in a base of acacia, sucrose and water. No disintegrant is included in compressed lozenges composition. Other additives (binder and filler) must have pleasant taste or feeling during dissolution. Common binder used in compressed lozenges is gelatin, common fillers are sorbitol, mannitol and glucose.

If the lozenge is to be used to enhance buccal or sublingual absorption, then a gelatin soft lozenge would be a good base since it dissolves slower than the polyethylene glycol bases. More drugs would be absorbed from the buccal cavity and less would be swallowed and lost in the GI tract. But the long contact time would limit gelatin's usefulness if the drug is extremely bitter or if the taste is hard to mask. The polyethylene glycol bases are more palatable for the patient and should be used if buccal or sublingual absorption is not a therapeutic goal.