Pharmaceutical dosageforms

Pharmaceutical dosageforms

o Pharmaceutical dosage forms are drug delivery systems: they are means of getting drugs into the body in a safe, effective and reproducible manner

o Drug substance are seldom administered alone, but rather as part of a formulation in combination with one or more non-medical agents (pharmaceutical ingredients) to give a practical dosage form : in other words the drugs must be formulated.

oIn addition to facilitate administration of     the drug, the dosage forms are needed for;           1-The protection of a drug substance from destructive influence of atmospheric oxygen or humidity (e.g.coated tablets and sealed ampoules)                                                                                                       
2-Protection of the drug from gastric acid after oral administration (e.g. enteric coated tablets).                                                                                                                                                                       
3-To mask the bitter, salty, or offensive taste or odor (capsules, flavoured syrup, coated tablets).                  

 4-To provide different  routes of drug administratione.g., oral, rectal, vaginal, topical, parenteral         lungs,  nasal, eye and ear.
  5-To provide time-controlled drug action (e.g., various controlled release tablet, capsule and    suspension).                                                                                                                                     

Before a drug substance can besuccessfully formulated into a dosage form manyfactors must be considered

1.Biopharmaceutical considerations, including factors affecting the absorption of the drug from different administration routes.
2.Drug factors, such as the physical and chemical properties of the drug.
3.Therapeutic factors including consideration of the disease to be treated and patient factors.

PHARMACEUTICA SOLUTION

Are liquid dosage forms that prepared by dissolving the active ingredients in an aqueous  or non-aqueous solvents.

Solution for different routes of administration:

1.Orally (syrups, elixirs, drops)
2.In mouth and throat (mouth washes, gargles, throat sprays)
3.In body orifices (enemas, ear drops)
4.In body surfaces (collodions, lotions, paints).

Advantages of solutions:

1. Young children and some adults have difficulty  in swallowing tablets and capsules.

2-They are more quickly effective than tablets  and capsules (solution > suspension > capsules  >tablets >coated tablets)

3-They give uniform dose than suspension due  to no need for shaking.

4-They dilute the irritant action of some drugs like I, KBr.        

•Disadvantages of solutions:

1. They are bulky to carry around

2. Difficult to mask bad taste or odor.

3. Need accurate spoon to measure the dose.

4. Less stable than solid dosage forms (precipitation, chemical and microbiological gasformation, color changes are major signs of solution instability). 

Capsules

                                   Capsules

•Are solid dosage forms that are more commonly composed of gelatin and are designed to contain a drug containing formulation.

•Types of capsules:

1-Hard gelatin capsules.

2-soft gelatin capsules

•-Hard gelatin capsulesare less flexible and composed of two pieces the cap and the bottom.

•-Soft gelatin capsulesare flexible and are composed of one piece of capsule shell.

•Many formulation type can be added interior of the capsules. For example:

–powders, tablets,semisolids and non aqueous liquids / gels may be filled in the hard capsules.

–Soft gelatin capsules are usually filled with various liquids containing AC either dispersed or dissolved within the carrier.

2 Advantages of capsules formulations:

1) The use of capsules avoids many operations associated with tablet manufacture such as compression, granulation, drying.

2) Capsules may be formulated to increase oral bioavailability of poorly soluble therapeutic agents.

3) It is a convenient method where orally administered liquid in a single dosage forms.

4) The stability of the drug may be improved in capsule formulation.

Disadvantages of capsules formulation:

1. Requirement of specialized manufacturing equipments.

2. Stability problems are associated with capsule containing liquid fills.

3. Problems regarding the homogeneity of fill weight and content may are associated with capsule formulations.
3.Gelatin as the main material in manufacturing capsules Shell:

Gelatin is a mixture from animal collagen extracted from animal skin or bones by either partial acid extraction (type A )or partial alkaline hydrolysis (type B).

The use of gelatin as a capsule material is due excellent physicochemical and biological properties and has the advantages:

1.Non toxic material.

2.Soluble in biological fluids at room temperature.

3.Excellent mechanical properties.

4.Excellent rheological properties at elevated temperature.

5.Undergoes a gel-sol transition at relatively low temperature.