Drug Formulations & Routes of Administration Ma. Minda Luz M. Manuguid, M.D.
Pharmaceutics – branch of Pharmacy that deals with drug formulations
Pharmaceutical products need to be presented in a form that can be administered to an organism
Formulation takes into consideration easy delivery as well as guaranteed desired action (drug reaches target, achieves therapeutic action)
Pill – round or ovoid solid body; may be coated with sugar or other substance
Tablet – granulated powder containing one or more medications, compressed into a disc; must disintegrate in the GIT, so starch is often incorporated; + sugar-/film- coating;
Dragees – chewable tablets
Enteric-coated tablets – coated with a substance that is stable at acidic pH (will not disintegrate in the stomach) but breaks down rapidly at higher pH (small intestines)
Capsule – an outer “shell” holds the drug inside
Hard gelatin capsule – contains solid drug in powder form; may be opened
Soft gelatin capsule – contains the drug in liquid or semi-liquid form; cannot be opened; useful for drugs that are insoluble in water
Sustained/Slow-release preparations – drug is formulated in such a way that it releases very slowly in the GIT; a single dose suffices for delivery of the drug over a period of hours, ensuring sustained action.
Liquid preparations – for children & for adults who have difficulty swallowing pills; usually flavored to make them palatable;
Elixirs – drugs insoluble in water are dissolved in Alcohol
Syrups – sugared liquid preparations
Suspension – drug in solid form, not dissolved in Alcohol
Emulsion – drug in liquid form, not dissolved in Alcohol
Topical – application of a drug to the skin/ mucosa overlying the area to be treated
Drops – isotonic solutions – ophthalmic, nasal, otic (eardrops – formulated as oily solutions for adherence to the aural cavity)
Creams – water-based, poorly absorbed; drug is left on skin surface as water evaporates
Ointments – lipid-based, greasy appearance & feel; drug penetrates deeply into tissues, especially if with “occlusive” dressing
Pastes – have a very high powder content; water-repellent.
Gels & Lotions – used on hairy parts of the body.
Intranasal sprays – often metered to deliver precise doses of the drug; can be absorbed systemically
Transdermal patches – useful for administering lipophilic drugs & those that are active in very small amounts
Suppositories – useful in nauseous or vomiting patients, unconscious patients, patients with difficulty of swallowing; may be administered rectally or vaginally ( Pessaries )
Routes of Administration
Routes of Administration
most convenient, most economical
rate & extent of absorption determines onset of drug action/effect
usual site of absorption: small intestines
nonionized lipid-soluble forms favor absorption
weak acids are highly ionized in small intestinal alkaline pH
weak acids are readily absorbed in the stomach
First pass effect:
Drugs absorbed from the GIT passes through the portal venous system, then through the liver before finally reaching the systemic circulation, to the receptors & target tissues
Extensive hepatic metabolism/extraction results in minimal drug delivery to the systemic circulation (e.g.propranolol,Demerol, INH)
poor liver extraction, ↑bioavailability e.g. diazepam, warfarin
emesis due to GIT irritation
destruction of drug by gastric acid/ GI enzymes
unreliable or inconsistent absorption
metabolism of drug by intestinal flora
Sublingual literally means 'under the tongue'. It is a method of administering substances by placing the medication under the tongue to gain rapid and direct entry into the blood vessels rather than via the digestive tract. Medically, sublingual drug administration is applied in the field of cardiovascular drugs.
comes in contact with the mucous membrane, or buccal mucosa, it diffuses into the epithelium beneath the tongue, the sublingual areas act like a blotting paper, readily soaking up the substance. This region contains a high density of blood vessels, and as a result, via osmosis, the substance quickly enters the blood stream at the sublingual artery and thereafter, polypeptide-k ® is carried by blood flow to the connected lingual artery.
Can all substances be administered sublingually? Not all substances are permeable and accessible to the buccal mucosa. In order for a nutrient to be effectively absorbed sublingually, it needs to be able to travel accross the buccal mucous membranes; by a process of diffusion known as osmosis and factors, such as pH, molecular weight, and lipid solubility of a substance may determine whether the route is possible.