Lecture 3: Solid Dosage Forms & Delivery Systems PDF

III. Solid Dosage Forms a. Powders Powders (pulvis, in Latin) represent a mixture of finely divided drugs and/or chemicals in dry form. They may be used internally or externally. “Powders” is one of the dosage forms. “Powder" is the physical state of a singl...

III. Solid Dosage Forms a. Powders Powders (pulvis, in Latin) represent a mixture of finely divided drugs and/or chemicals in dry form. They may be used internally or externally. “Powders” is one of the dosage forms. “Powder" is the physical state of a single chemical or drug. The powders may contain: 1. Small proportions of liquids dispersed uniformly over the solid components of the mixture. 2. Solid materials only. Dean. Prof. Mina Tadros  b. Granules They are irregular shaped agglomerates of smaller particles and behave as single larger particles. They can be prepared by many methods. Of these methods, the wet method involves: 1. The desired powder or powder mixture is moistened. 2. The moistened mass pass through the mesh screen that will produce the desired size granules. 3. The granules are then dried (by air or heat according to drug sensitivity to heat). 4. Occasionally, they are moved on the drying trays to prevent their adhesion. Effervescent Granules: Are special granules that can be used to provide a pleasant vehicle for selected drugs especially those with either a bitter or salty taste. → They cause a numbness sensation to the taste buds of the tongue. It may consist of mixtures of: Citric acid, tartaric acid combined with sodium bicarbonate. A good effervescent blend consists of citric acid and tartaric acid (1:2 ratio).  c. Capsules Are solid dosage forms in which one or more medicinal substances are enclosed within a small shell. They are generally prepared from a suitable form of gelatin. The gelatin capsule shells may be hard or soft. Soft gelatin capsules Hard gelatin capsules  d. Tablets Are solid dosage forms of medicinal substances that are usually prepared with the aid of suitable pharmaceutical additives. They may vary in size, shape, weight, hardness, thickness, disintegration depending upon their intended use and method of manufacture. The majority of tablets are used for the oral administration of drugs. Other tablets such as those intended to be administered via sublingual, buccal, or vaginal delivery do not contain the same additives or be prepared to possess the same properties of oral tablets.  Sterile dosage forms a. Parenteral Preparations The injections are sterile, pyrogen-free preparations intended to be administered parenterally. The term “parenteral” refers to the injectable routes of administration. It is derived from the Greek words “para” and “enteron” meaning outside of the intestine “other than oral route”. “Pyrogens” are fever-producing organic substances arising from microbial contamination. The parenteral routes of administration are preferable when… 1. Rapid drug action is desired, as in emergency situations with IV injections, 2. When the patient is uncooperative, unconscious, or unable to accept or tolerate oral medication, 3. When the drug itself is ineffective by other routes. Insulin injections are self-administered by diabetic patients. Other injections are administered by a physician, or a nurse.  b. Ophthalmic Drug Delivery Drug delivery systems applied topically to the eye include: solutions, suspensions, gels, ointments and inserts. The normal volume of tear fluid retained in the cul-de-sac of the human eye is ≈ 7 - 8 μL. A single drop of an ophthalmic solution or suspension measures about 50 μL → much of the administered drop will be lost. Excessive amounts of liquids, “if normally produced or are externally delivered”, are rapidly drained from eye. Recently, micro-liter single dosing eye droppers were introduced so that an optimal volume of 5 to 10 μL is administered. However, larger volumes of liquid preparations may be used to flush or bathe the eye during examinations and/ or operations.  Due to the dynamics of the lacrimal system, 1. The retention time of an ophthalmic solution on the eye surface is short, 2. The amount of drug absorbed is usually only a small fraction of the quantity administered. Formulations like gels are needed to: 1. Extend corneal contact time. 2. Decrease frequency of dosing. 3. Increase ocular drug absorption.  c. Inhalations Aerosol drug delivery has been used for the local modulation of the respiratory functions as in the treatment of asthma and local infections of lung, as pneumonia. The systemic delivery is possible due to the rapid drug absorption in lung into the blood circulation. Advantages: Minimizes drug loss. Enhances drug absorption leading to systemic absorption of drugs with comparatively low bioavailability. Targeted delivery systems, avoid toxic effects following systemic administration.  Inhalation delivery systems Metered dose inhalers Dry powder inhalers Nebulizers (MDIs) (DPIs) Ultrasonic Air jet Multi dose Single dose Multi dose