Dosage Forms and Administration

Routes of Administration

As the name suggests, the route of administration refers to the method or pathway through which a medication or drug is introduced into the body. It describes how a drug is delivered to its intended site of action or absorption.

A prescriber must take into account the route of administration when prescribing the medication as this influences the speed of drug absorption, the extent of systemic or localized effect, and the potential for adverse effects.

Dosage Forms

The physical display of a drug that is designed to deliver the medication by a specific route of administration.Dosage forms are adapted to different routes of administration depending on their intended uses.The dosage form selected is the one best suited to produce the desired systemic or localized effect in either an immediate or time-delayed manner,

  • Tablet

  • Capsule

  • Patch

  • Ointment

  • Drops

  • Paste

  • Cream

  • Gel

  • Solution

  • Suspension

  • Suppository

  • Troche

Local Routes of Administration

Advantages: 

  • Targeted effect

  • Reduced systemic side effects

  • Higher local drug concentration

  • Minimized drug interactions 

Disadvantages:

  • Limited systemic effect

  • Can be Invasive 

  • Local irritation or side effects

  • Limited duration of action

When a drug produces a LOCAL effect, it primarily acts at the site of administration or in the immediate vicinity. The drug's action is confined to a specific area, such as the skin, mucous membranes, or a particular organ. 

For example:

  • Topical creams or ointments are often used for skin conditions, and their effect is localized to the area where they are applied.

  • Eye drops are primarily used for treating eye conditions and have a local effect on the eyes.

Systemic Routes of Administration

When a drug produces a SYSTEMIC effect, it is absorbed into the bloodstream and distributed throughout the body, affecting various organs and tissues. It produces effects beyond the site of administration. Examples include:

  • Oral medications are absorbed through the gastrointestinal tract and enter the bloodstream, allowing them to exert systemic effects on different organs.

  • Intravenous injections deliver drugs directly into the bloodstream, resulting in rapid distribution and systemic effects throughout the body.

Various Routes of Administration

  • By mouth

  • Transdermal

  • Intravenous

  • Intramuscular

  • Intradermal

  • Intrathecal

  • Rectal

  • Vaginal

  • Sublingual

  • Buccal

You will notice that there are two different types of systemic routes: parenteral and enteral.

The main difference between the parenteral and enteral routes of administration is how the medications or substances are introduced into the body.

Parenteral: The parenteral route involves administering medications or substances outside the gastrointestinal tract, bypassing the digestive system

Enteral: The enteral route involves administering medications or substances through the gastrointestinal tract

A dosage form is the physical manifestation of a drug—such as a tablet, capsule, suspension, ointment, cream, patch, or injection—that is designed to deliver the medication by a specific route of administration.

The dosage form selected is the one best suited to produce the desired systemic or localized effect in either an immediate or time-delayed manner. 


The routes of administration for drugs intended to have a systemic effect are:

Oral enteral, which means into mouth and swallowed. Dosage forms include Tablets, capsules, syrups, and suspensions

Transmucosal, or through mucous of inner linings. Dosage forms include Lozenges, sprays, troche tablets, and effervescent tablets.

Topical transdermal, or absorbed through the skin. Dosage forms include Creams, ointments, pastes, patches, plasters.

Inhalation/intrarespiratory,  or breathed in. Dosage forms include Dry powder inhalers, metered-dose inhalers, and nebulizer solutionss

Parenteral/injection, or injected into muscle, skin, or under the skin. Dosage forms include Injection shots, injectable pen solutions, and IV solutions.

Rectal and vaginal, which may be transdermal and/or transmucosal. Dosage forms include Rings, suppositories,  and solutions.

And implants. Dosage forms include Pumps, radiation seeds, stents, and wound dressings.


The routes of administration for drugs intended to have a localized effect are:


Topical dermal, which means on or in the skin. Dosage forms include Creams, lotions, ointments, powders, and solutions.

Inhalation, or breathed in. Dosage forms include Dry powder inhalers, metered-dose inhalers, and nebulizer solutions.

Transmucosal, or through mucous membranes which may be through the nose, eyes, or ears. Dosage forms include Sprays, solutions, and suspensions

And vaginal and rectal, which may be transdermal and/or transmucosal. Dosage forms include: Suppositories, solutions, creams, gels, and ointments.

Oral Routes of Administration:
Enteral (oral) route of administration

  • Gastrointestinal tract

  • Metabolized

  • System effect

  • Slow onset of action (30min)

Solid dosage forms and oral liquids are swallowed and absorbed through the gastrointestinal tract.

Any medication administration that passes through the gastrointestinal tract for systemic circulation is referred to as an enteral route of administration. 

Enteral administration by drinking, swallowing whole, or chewing and swallowing is also known as the oral route of administration.

The term oral can also refer to a medication applied topically to the mouth or to other dosage forms that are put into the mouth cavity. 

Oral dosage forms pass through the mouth and throat into the stomach; dissolve in the stomach or small intestine; metabolize, which is the transformation of food into energy, in the liver; and distribute to the tissue or target organ.

ORAL: It is the most convenient and most commonly used route of administration.

Advantages: 

  • Ease of administration.

  • Patient compliance

  • Absorption control

  • Flexibility in formulation

  • Cost-effectiveness

Disadvantages

  • Variable absorption… factors such as gastrointestinal pH, food intake, and interactions with other substances can affect the rate and extent of drug absorption. 

  • First-pass effect (when drugs are taken orally, they pass through the liver this can significantly alter the concentration and bioavailability of drugs)

  • Gastrointestinal irritation: 

  • Patient adherence and swallowing difficulties:

  • Slow onset of action

Oral Formulations: Oral administration is the most frequently used enteral route of administration.

  • Oral meds are primarily absorbed in the stomach and/or intestine.

  • Oral meds go into the stomach first which is very acidic (pH 1-2).

  • Absorption can be affected by presence of food.

Gastrointestinal Action:

Disintegration and dissolution begins in the stomach. Continues when the stomach contents empties into the intestine.

  • Disintegration: tablet breaking into smaller pieces

  • Dissolution: when smaller pieces of disintegrated tablet dissolve into solution

  • pH: acidity or alkalinity of substance. Neutral pH is 7. Below 7 is acidic above 7 is alkaline.

Types of Oral Formulations:

  • Solid Formulations

    • Tablets, Capsules, Bulk Powders

  • Modified Release Formulations

    • SR, ER, XR, LA

  • Liquid Formulations

    • Solution, syrup, elixir, gels, tincture, suspension, emulsion

What Pills are Made of:

  • Tablets are made by compressing active and inactive ingredients into a solid form.

  • The inactive ingredients are called excipients.

    These inactive ingredients, or “excipients” are used to help manufacture the formulation and to help the dosage form disintegrate & dissolve when administered. 

Oral drug compounds contain one or more active ingredients along with inert ingredients. Inert ingredients have no therapeutic effect but they fulfill functions of the compound that are not directly related to the medicinal purpose.

A binder promotes adhesion of the materials in the tablet. An example would be methylcellulose.

A coating Assists the patient’s swallowing of the tablet and may improves the flavor. An example of a coating that would improve the flavor is saccharine.

Coloring provides tablet identification. Only FDA-approved coloring agents and dyes are allowed.

A diluent Allows for appropriate concentration of the medication in the tablet. An example would be lactose. 

A disintegrant helps break up the ingredients once the tablet has been consumed. An example would be starch.

A lubricating agent gives the tablet a slippery sheen. An example would be talc.

And a solubilizer maintains the ingredients in solution. An example would be cyclodextrin.

Tablets: Tablets are one of the most common forms of oral administration. The tablet is a solid dosage form produced by compressing dry drug ingredients of either powder or granules (small particles or crystals).

On the whole, tablets are easier and less costly to produce in bulk than other forms, so they are often cheaper. For patients, tablets offer low cost, more precise dosing, and increased usability due to specialized coatings.

Sugar coated tablets mask the bitter taste of some drugs. Film coated tablets are used to protect the stomach lining. 

A chewable tablet contains a base that is flavored and/or colored. The dosage form is designed to be chewed and absorbed quickly for a slightly faster onset of action. Chewing is preferred for antacids, antiflatulents commercial vitamins, and tablets designed for children.

Large pharmaceutical manufacturers use heavy tool and die machinery to make compression tablets. In the process, the powder or granular ingredients are compressed to produce a tablet as the end product.

  • Sugar-coated and film-coated

  • Chewable tablets must be masticated

  • Buffered tablets

  • Compression tablets

  • Can be delayed release

  • Orally disintegrating tablet (ODT)

  • Enteric coated

  • Scored

  • Enteric coated tablets are used to prevent drugs from degrading in the stomach acid.

  • The enteric coating prevents the tablet from disintegrating in the acidic environment of the stomach.

Delayed Release Tablets: Release is slower to provide longer duration

  • Fewer side effects

  • Patient compliance

  • Do not cut, crush or chew

  • ER, DR, XL, XR, SA, LA, SR

  • If a patient has a hard time swallowing tablets

    • Coated tablets

    • ODT

    • Switch to liquid or capsule

    • Use a thick beverage

    • Never attempt to swallow dry

  • Never cut, crush, or chew a delayed release tablet

  • If the tablet is scored it can be cut

  • If you need to cut a tablet that isn't scored, use a pill cutter

Capsules:

  • Granular powder or liquid gel enclosed in a gelatin shell

  • Sprinkle caps

  • Longer portion is body and shorter portion is cap

  • Caplet – capsule shaped tablet

  • (+): easier to swallow, have a more rapid dissolution and faster onset of action

Time- Released Capsule: designed to deliver a dose of drug over an extended period of time

Advantage: decreased frequency of administration

Liquid Dosage Forms:

  • Solutions 

  • Suspensions

  • Emulsions

  • Colloids

  • Advantages: faster onset of action than solid dosage forms, easy to administer, individualized dosing; can be flavored.

  • Disadvantages: often less stable

Solutions: Liquid with active ingredients completely dissolved. 

  • Liquid base is a solvent

    • Aqueous solutions

    • Alcoholic solutions

    • Hydroalcoholic solutions

  • Prepared by dissolving the solute (the active drug) in a liquid solvent; water and alcohol are used to dissolve some solutes

  • Coloring and flavoring may be added to solutions

Elixir: liquid drug forms with alcohol base; should NOT be availiable to those with an alcohol addiction

  • Syrups - sugary solution 

    • Sucrose

    • Sorbitol

    • Propylene glycol

    • Preferred for children (no alcohol content)

    • Because of high sugar content use with caution with diabetic patients

    Emulsions

  • Dispersion of two unblendable substances 

  • Must shake well

  • Emulsifying agent helps make stable

Suspensions:

  • Solid particles remain undissolved in the liquid after mixing

  • Also called a dispersion; must have suspendability

  • Must shake well

  • Often contain coloring or flavoring

  • Some antibiotics come as a powder that you reconstitute with sterile water. 

    • Stable 7-10 days at room temperature; 14 days if stored in refrigerator; depending on storage requirements

    • Most stored in refrigerator (14 days)

    • Azithromycin (Zithromax) and cefdinir (Omnicef) are stored at room temperature

Colloids:

  • Mixture have physical properties between those of a solution and fine suspension

  • Magma is a milk-like colloid (MOM)

  • Microemulsion is a liquid in another liquid but is clear

Liquid Medications:

  • Always use dosing spoon, oral syringe, dosing cup, or medication dropper

  • Suspensions must be shaken well

  • If you mix it in another liquid, be sure the whole amount is consumed

Powders and Effervescent Salts

  • Effervescent salt mixtures contain a drug and sodium bicarbonate with citric acid, tartaric acid or sodium biphosphate and carbon dioxide  is release when water is added.

Transmucosal Routes of Administration
A transmucosal route allows for absorption of the drug through or across the permeable mucous membranes of the eyes, ears, nose, vagina, rectum, and urethra.  Used primarily in patients who need immediate relief of symptoms.

Advantages: rapid onset of action and increased effectiveness of drug with lower incidence of unpleasant side effects; bypasses digestive system

Disadvantages: difficult to reverse negative effects of drug

Oral Transmucosal Forms: (tablets, gum, troches and lozenges)

Sublingual: the drug is placed under the tongue (not swallowed) and absorbed thru the blood vessels.


Advantages: rapid onset for immediate relief; avoidance gastrointestinal irritation; ease of administration

Disadvantages:  short duration of action (less than 30 to 60 minutes); taste and tolerability; saliva interference:  irritation of oral mucosa

Buccal: drug is placed between the gums and the inner lining of the cheek. 

ex) nicotine gum, lollipop-like lozenge, also known as troche.

Used commonly for local therapeutic effects.

Advantages: rapid drug absorption, ease of administration; Bypasses first-pass metabolism

Disadvantages: unpleasant taste, local mouth irritation; eating drinking and smoking can affect the absorption of the drug; inconvenience; small dose limit; advantages lost if swallowed

Ophthalmic, Otic and Nasal Transmucosals
Ocular Route of Administration: 

  • Formulations are called ophthalmics. 

  • Often used for localized effect 

  • Only use sterile solutions, suspension and ointments. 

  • If used repeatedly they must contain a preservative.

Solutions have a more rapid onset of action than suspensions but suspensions have a longer duration of action. They are NOT interchangeable. 

Ophthalmic formulations can be used in the ear, however, ear formulations cannot be used in the eyes because they are not sterile

Ophthalmic Administration

  • Eye drops

  • Eye suspensions (shake)

  • Eye ointments

  • Wash hands

  1. If it is a suspension, shake it

  2. Tilt head back

  3. Make a pouch in lower lid by gently pinching and pulling downward

  4. Instill drop or ointment. Do not touch tip of applicator to eye

  5. Close eye for 1 – 3 minutes while applying gentle pressure to lacrimal gland

    Eye drops can go in the ear, but ear drops can NEVER go in the eye!!!!

    Otic Route of Administration:

    • Solution or suspension, not interchangeable 


    Intranasal Route of Administration:

    • Spray: dosage form that consists of a container with

     a valve assembly unit that when activated emits a 

    fine dispersion of liquid.

    Rectal, Vaginal and Urethral Transmucosal Routes of Administration

    Rectal Route of Administration: used to deliver drugs in the rectum. Rich supply of blood vessels for absorption and local and systemic action

    • Suppositories, solutions, ointments, creams and foams.

    • Uses: hemorrhoids, bowel cleansing, constipation


    Advantages: 

    • can be used if an oral drug is diluted or destroyed by acidic fluids in the 

    stomach

    • If an oral drug is too readily metabolized by the liver and eliminated from 

    the body

    • Patient is unconscious and needs medications

    • Patient is experiencing nausea and vomiting or severe acute disorders of 

    the GI tract

    • Use in young children: glycerin supp, APAP, and promethazine


    Disadvantages:

    • Inconvenience

    • Discomfort

    • Premature expulsion


    Enema: a water-based solution administered rectally for evacuating the bowel 

    or administering a drug


    Vaginal Route of Administration:

    • Vaginal tablets, suppositories, creams, 

    • foams, inserts, rings, solutions and sponges

    • Used for cleansing, contraception, hormone replacement therapy, and to treat bacterial and yeast infections, 

      Urethral Route of Administration: application of the drug within the urethra, the duct that delivers urine out of the body. 

      Often used to treat cancer, incontinence, and impotence in men.

    • Dosage Forms: implants, tablets and suppositories. 

      Topical Routes of Administration

      1. Dermal: topical applications that provide a localized effect on the skin layers.


      1. Transdermal: topical drug applied to a specific area on the skin that is absorbed systemically through the dermal and muscle layers into the bloodstream; faster onset of action than oral dosage form; no first-pass metabolism

The topical route of administration typically refers to applying a drug directly to a specific area on the skin surface. 

There are two routes of topical administration: dermal and transdermal. 

Dermal routes of administration refer to those topical applications that provide a localized effect on the skin layers. The transdermal routes of administration refer to drugs applied to a specific place on the skin and absorbed through both the dermal and muscle layers into the bloodstream.

DERMAL DOSAGE FORMS

OINTMENTS :

  • An ointment is a dosage form that's a water-in-oil emulsion.

  • Ointments may be more therapeutically effective due to their skin adherence, but they aren't as cosmetically acceptable as creams.

  • May be non-medicated or medicated, prescription or OTC.

  • Especially good for extremely dry areas of the skin where moisture needs to be retained as well as for areas prone to friction from clothing or other body parts

  • Generally have a longer contact time with the skin = ointments have a longer duration of action than creams, lotions, and gels

  • Disadvantage: longer time to absorb and often a greasy residue on the skin.

PASTES:

  • A paste is a water-in-oil emulsion containing more solid material than an ointment, creating a denser consistency, making the application of a paste thicker than that of an ointment.

  • Ex: zinc oxide paste (astringent and sunscreen) and triamcinolone acetonide paste (anti-inflammatory dental preparation).

CREAMS:

  • Emulsions of oil and water 

  • Creams that are water-in-oil emulsions contain a small amount of water dispersed in an oil base, which are moisturizing

  • Others are oil-in-water emulsions, which is less greasy

  • Most are considered “vanishing” which means they’re invisible once applied and rubbed into skin, making creams cosmetically acceptable to most patients 

GELS:

  • Like a suspension, a gel contains solid particles in a liquid, but the particles are fine or ultrafine.

  • Topically, gels apply evenly and leave a dry coat of the medication in contact with the area. 

  • Example: prescription drug diclofenac (Voltaren), a topical medication used to treat arthritis providing relief to an aching knee without the risk of GI effects associated with the oral formulation.

  • Ultrafine gel dispersion dosage form is a jelly

  • gel that contains a higher proportion of water in combination with a drug substance and a thickening agent. 

LOTION:

  • A lotion is another o/w emulsion for topical application

  • Are easily absorbed and can cover large areas of the skin and are especially effective for hairy areas of the body, such as the scalp. 

  • Examples: calamine lotion, used for the relief of itching, and benzoyl peroxide lotion, used to control acne.

WHAT IS TRANSDERMAL?
Refers to drugs applied to specific places on the skin and absorbed through both the dermal and muscle layers into the bloodstream, resulting in systemic absorption

  • Transdermal medications have a slower onset of action than dermal medications, because of the longer time to reach the bloodstream. Transdermals, though, usually have longer-lasting effects, the therapeutic effects can last from 24 hours to one week

  • Can be affected by skin thickness and blood flow, which vary with age.

  • Commonly used for cessation of smoking (nicotine); chest pain (NTG); pain relief; lower BP (clonidine); motion sickness (scopolamine); birth control or hormone replacement ( estrogen. Progestin, testosterone)

Patch and Disk 

  • Transdermal patches or disks consist of adhesive fabric backing holding a drug reservoir with a rate-controlling membrane.

The chemicals in the patch or disk force the drug across the membranes of the skin and into the deepest layer of skin and fat where optimal absorption into the bloodstream will occur.

  • Adhesives should not be placed on the following areas: scar tissue or damaged skin 

Because it can increase or decrease the release of the drug and alter its therapeutic effect.

  • Patches and disks are most typically placed on the upper arms or wrists.

    Lidoderm

    • A transdermal patch of lidocaine and nitroglycerin that provides 24 hours of relief from Postherpetic neuralgia*

    • Physicians advise patients to remove the lidoderm patch at bedtime to prevent the development of drug tolerance.

  • Fentanyl Patch

    • A transdermal patch of fentanyl that relieves chronic pain for up to three days.

    • What Schedule and class does fentanyl belong to?

Schedule II opiate analgesic

  • When using fentanyl patches, patients should avoid:

Sun exposure, heating pads, electric blankets, heat lamps, saunas, hot tubs, and heated water beds

  • Why is this important?

Heat can speed up the movement of fentanyl from the patch into the body, creating a higher risk for a serious drug overdose

Gels, Lotions and Sprays

  • Have less of a time release mechanism than patches and disks and less long-lasting

  • Can be washed off

PARENTERAL ROUTES

Eye & ear drops

  • Intranasal

  • Inhalers (oral)

  • Topical

  • Vaginal

  • Injectables

Why would parenteral meds sometimes be preferred over oral meds?

  • Absorptions limits

  • Time of onset of action

  • Patient limitations

Disadvantages:

  • Cost

  • Administration

  • Once administered cannot reverse

  • Risk of needle use with injectables.

Preperation:

Sterile preparations:

  • Injectables

  • Ophthalmic

  • Intranasal

  • Inhalation

  • Otic

  • The injectable route is used often for immediate systemic effect (IV bolus and infusions)

  • Most injectable preparations are dissolved or reconstituted in sterile solutions like dextrose in water or normal saline

  • Products are often in single-use vials or ampoules that do not contain preservatives or a multi-dose vial with preservatives.

Subcutaneous: 

  • Absorbed faster than oral but not as fast as IM.

  • Subcutaneous route can be used for short term and very long term therapies.

  • Injection is made into the fat layer, or subcutaneous tissue, just under the skin

  • Examples: insulin, heparin, enoxaparin, immunizations, epinephrine 

  • Insulin

  • 5/8 inch