Drug Dosage Forms Notes

Drug Dosage Forms

Drugs can be administered to a patient in various forms. They are available as solid,
semisolid and liquid dosage forms.

Solid Dosage Forms

Solid dosage forms of a drug are tablets, capsules, powders, suppositories, troche, lozenge, etc.

1. Tablet: It is the commonly used solid dosage form. A tablet may be scored and can be easily broken along the line if required, for example paracetamol. Tablets can be uncoated or coated (covered with a thin film of another substance) to improve the taste, delay absorption, prevent its degradation in the stomach, etc. The sugar coating of a tablet helps to improve its taste, for example, metronidazole.

Read And Learn More: Pharmacology for Dentistry Notes

1. • Solid Dosage Forms
     • Tablet
     • Capsule
     • Troche
     • Lozenge
     • Suppository
     • Powder
   • Enteric-coated tablet: It is coated with a material that delays the release of medication till it reaches the intestine. Enteric coating of a drug prevents the destruction of the drug by gastric acid, for example, enteric-coated tablet of erythromycin, or decreases the gastric irritation by the drug, for example, enteric-coated tablet of diclofenac.
   • Sustained-release preparation: It helps to prolong the duration of action of a drug, thereby decreasing the frequency of drug administration and improving patient compliance, for example, sustained-release tablets of diclofenac (for pain).
   • Chewable tablet: It should be chewed and swallowed. This helps to increase the effectiveness of the drug, for example, a chewable antacid tablet used for gastritis and a chewable albendazole tablet for worm infestation.
   • Dispersible tablet: It is a tablet that has to be dispersed in water or milk before administration, for example, a dispersible aspirin tablet.
   • Mouth-dissolving tablet: It is placed on the tongue— disintegrates rapidly within few seconds, for example, a mouth-dissolving tablet of ondansetron, an oral disintegrating strip of methylcobalamin, etc. It is easy to administer, convenient for the patient and does not require water for swallowing. The tablet/strip should be handled carefully. It is not suitable for patients with dry mouth (for example, those on anticholinergics).
   • Capsule: It is a solid dosage form where the drug is enclosed within a soluble sheath. Capsules can be oval, cylindrical or spherical, for example, amoxicillin. Sustained-release and enteric-coated capsules are also available. Spansules and Timesules are sustained-release forms. Time-release forms may have suffixes like SR (sustained release), CR (controlled release), ER (extended-release), SA (sustained action), Contin (continuous) and retard.
2. Troche: It is a solid dosage form to be placed in the mouth where it dissolves slowly to liberate the active ingredient. For example, clotrimazole troche is used for oral candidiasis (oral thrush).
3. Lozenge: It is a solid dosage form placed in the mouth and sucked; it dissolves slowly to liberate the active ingredient. It soothes the irritated mucosa of the throat. Some lozenges have systemic effects, for example, nicotine lozenges to reduce withdrawal symptoms and craving associated with cessation of smoking; dyclonine (local anaesthetic) lozenges for sore throat. Nystatin lozenge is used for oral and oropharyngeal candidiasis.
4. Suppository: A solid dosage form that is inserted into the rectum, for example, a bisacodyl suppository for constipation.
5. Powder: It is the finely divided form of a drug for internal or external use, for example, oral rehydration salt (ORS) powder for dehydration, tooth powder for cleaning the teeth, etc.

Semisolid Dosage Forms

Different types of semisolid dosage forms are as follows:

1. Ointment: It is a semisolid preparation with a greasy base usually meant for application to skin or mucosa, for example, lignocaine ointment for local anaesthesia, acyclovir ointment for herpetic infections and hamycin ointment for oral thrush.
2. Cream: It is a semisolid emulsion for local application, for example, antifungal agents (nystatin and clotrimazole cream) for oropharyngeal candidiasis; antiviral agents (acyclovir and penciclovir cream) for herpetic labialis; glucocorticoid (betamethasone and clobetasol) intraoral cream for severe aphthous stomatitis.
3. Paste: It is a semisolid preparation with a less-greasy base generally meant for topical use, for example, triamcinolone acetonide paste for oral inflammatory conditions and toothpaste for oral hygiene. Pastes are stiffer and easily washable than ointments.
4. Gel: It is a jelly-like substance formed by the aqueous suspension of insoluble drugs, for example, diclofenac gel for pain, lignocaine gel as a local anaesthetic, povidone iodine gel for sore throat, glucocorticoid (betamethasone and clobetasol) gel for severe aphthous stomatitis.

Liquid Dosage Forms

Different types of liquid dosage forms are as follows:

1. Mixture: It is a liquid containing two or more ingredients for oral use. For example, sodium salicylate mixture as an analgesic and antipyretic; gripe water mixture used in infants to reduce griping; carminative mixture to expel gas from the stomach and intestine.
2. Emulsion: It is a mixture of two immiscible liquids (for example, oil and water) made miscible by using an emulsifying agent, for example, cod-liver-oil emulsion for vitamin D deficiency.
3. Suspension: It contains one or more insoluble ingredients suspended in a liquid, for example, antacid suspension and amoxicillin suspension. Suspension is also available for topical use, for example, hamycin suspension for oral thrush. It should be shaken well before use.
4. Syrup: It is a concentrated solution of sugar-containing the drug to mask the bitter taste of the drug, for example, cough syrup.
5. Elixir: It is a clear, pleasantly flavoured liquid dosage form that contains a drug dissolved in water and alcohol, for example, promethazine elixir for suppressing dry cough.
6. Linctus: It is a viscous liquid preparation that should be sipped slowly to allow it to trickle down the throat. It is usually used for the relief of cough, for example, linctus codeine.
7. Gargle: An aqueous solution used to prevent or treat throat infections, for example, saline gargle for sore throat.
8. Mouth rinses: An aqueous solution used for rinsing the mouth for oral hygiene, for example,
   • Antiseptic mouth rinse (chlorhexidine or povidone-iodine) is used in gingivitis.
   • Astringent mouth rinse (tannic acid) is used for gingivitis and aphthous ulcers.
   • Anticaries mouth rinse (sodium fluoride) to prevent dental caries.
     • Liquid Dosage Forms
       1. Mixture
       2. Emulsion
       3. Suspension
       4. Syrup
       5. Elixir
       6. Linctus
       7. Gargle
       8. Mouth rinses
       9. Tincture
       10. Paint
       11. Lotion
       12. Irrigation solutions
       13. Drops
       14. Spray
9. Tincture: It is an alcoholic preparation of a drug, for example, a tincture of iodine used as an antiseptic.
10. Paint: It is a liquid preparation of a drug for application to the skin or mucosa, for example, Mandl’s paint (iodine in potassium iodide) for sore throat, tonsillitis and pharyngitis; clotrimazole mouth paint for candidiasis; astringent gum paint (tannic acid) for gingivitis; and antiseptic gum paint (tincture iodine with phenol) for gingivitis and after scaling.
11. Lotion: It is a liquid preparation meant for topical application, for example, mometasone furoate lotion for aphthous ulcer.
12. Irrigation solutions: They are used for washing out a body cavity or wound and the procedure is known as irrigation. Water, saline and antiseptic solutions can be used as irrigants. Oral irrigation can be done for preventing and treating inflammatory conditions of the oral cavity.
13. Drops: They are liquid preparations meant for oral (vitamin drops, paracetamol drops) or local (eye, ear and nose) administration.
14. Spray: It discharges the drug in droplet form for topical application, for example, lignocaine spray for local anaesthesia, nitroglycerin lingual spray for acute attack of angina and beclomethasone spray for oral inflammatory lesions.

Injectable Dosage Forms

The drugs to be administered as injections are available as follows:

1. Powder for injection: The powder is mixed (reconstituted) with a diluent, for example, sterile water or normal saline before administration to a patient. The drug should dissolve completely before administration, for example, benzylpenicillin G.
2. Suspension for injection: Insoluble or sparingly soluble drugs are suspended in oily or aqueous vehicles, for example, procaine penicillin G.
3. Solution for injection: It is administered as such, for example, adrenaline.

New Drug-Delivery Systems

1. Orodental patch, for example, lignocaine patch for local anaesthesia.
2. Microspheres, for example, minocycline microspheres for periodontitis.
3. Computer-controlled local anaesthetic delivery devices.
4. Iontophoresis, for example, delivers salicylates for deep-seated pain.
5. Nanoparticles, for example, are nanoparticles loaded with chlorhexidine for antibacterial action.

Commonly used topical agents in dentistry are listed in Table.

Commonly Used Topical Agents in Dentistry