Routes & Formulations Flashcards
Formulations or Dosage Forms
Drugs are contained in dosing units
Route of Administration
A way of getting a drug into or onto the body.
- Enteral
- Parenteral
Enteral
Refers to anything involving the stomach from the mouth to the rectum
Parenteral
Routes other than enteral
Enteral Formulations
- oral (po)
- sublingual (sl)
- buccal
- rectal (pr)
Parenteral Formulations
- intravenous (IV)
- intramuscular (IM)
- ophthalmic
- intranasal
- inhalation
- dermal
- vaginal
Factors Affecting Selection of Route & Method of Administration
- Drug characteristics
- Ease of administration
- Site of action
- Onset of action
- Duration of action
- Quantity of drug administered
- Liver or kidney diseases
- Drug Characteristics
pH Scale
- measures the acidity of the alkalinity of a substance
- pH 7 is neutral (water)
- stomach is very acidic (pH 1-2)
- certain drugs are degraded or destroyed by stomach acids
- absorption of many drugs is affected by the presence of food in the stomach
- Drug Characteristics
pH Level
- stomach if very acidic (pH 1-2)
- duodenal pH is higher (closer is neutral)
- colonic pH is neutral to slightly alkaline
- Drug Characteristics
Drug Research Process
The influence of drug characteristics is examined and the formulations approved will have compensated for this
- Ease of Administration
- prescribers assess patient characteristics to determine route of administration
- difficulty in swallowing?
- consider liquid dose forms or non-oral routes of administration
- PO route may be inadvisable for patients w/ nausea and vomiting
- Site of Action
- route of administration may be influenced by desired site of action
- local effect
- systemic effect
- Site of Action
Local Effect
Site of drug activity and administration are one in the same
e.g. eyes, ears, nose, skin
- Site of Action
Systemic Effect
The drug is introduced into the circulatory system by any route of administration and carried by the blood to the site of action
- Onset of Action
Oral Medication
Since oral medications for systemic use need to go into solution to exert their effect, solutions or suspensions may work faster than oral tablets or capsules
- Onset of Action
Buccal or Sublingual (SL)
Medications placed under tongue or between cheek and gums work quickly because they bypass stomach and liver and go directly into bloodstream
- Onset of Action
IV
Drugs given IV directly are carried immediately throughout the body
- Onset of Action
Localized Therapeutic Effects
Those applied to the skin, inhaled into the lungs or instilled into eye
- Duration of Action
Length of time a drug gives the desired effect or is at the therapeutic level
- Duration of Action
Controlled or Extended Release
Drug effect lasts longer
e.g. 12 to 24 hrs
- Duration of Action
Transdermal Patches
Delivers small amounts of a drug steadily over many hours or even days
- Duration of Action
IV
Sustained duration effect can be achieved by means of intravenous infusion
- Duration of Action
IM and SQ
Injections into the muscle and skin last longer than injections directly into the bloodstream
- Quantity of Drug
- sometimes route of administration is chosen because of the amount of a drug
- IV infusion is an excellent method for systemic delivery of large quantities of material
- IV injections and infusions can deliver a higher dose of medication to the target site
- Metabolism by the Liver or Excretion by the Kidney
Liver Metabolism
Breaks down active drug to inactive metabolites for elimination and prevents drug accumulation
- Metabolism by the Liver or Excretion by the Kidney
First-pass Effect
- is the extent to which a drug is metabolized by the liver before reaching systemic circulation
- influences activity of some drugs
- such drugs have to be given in larger oral doses or by different route to bypass metabolism by the liver
- Metabolism by the Liver or Excretion by the Kidney
Effects of Age or Disease-related Change
- age or disease-related changes in liver or kidney function can cause:
- drug accumulation
- and potential toxicity
- drug dosage often needs adjustment in the elderly
- Metabolism by the Liver or Excretion by the Kidney
Multiple Potent Prescription
If patients are on multiple potent prescription drugs, there is a risk of a drug-drug interaction
- drug accumulation
- toxic blood levels increases
Oral Dosage Forms
Disintegration
The breaking apart of a tablet into smaller pieces
Oral Dosage Forms
Dissolution
When the smaller pieces of a disintegrated tablet dissolve in solution
Inactive Ingredients
- include binders, lubricants, fillers, diluents, and disintegrates
- added to help manufacture the formulation & to help the dosage form disintegrate & dissolve when administered
Most Frequent Route of Administration
- is PO
- oral refers to two method
- applying topically to the mouth for local effect
- swallowing for absorption through the GI tract into systemic circulation
Common Dose Form for Enteral
Solid Formation
- tablets
- capsule
- bulk powders
- rectal formulations
Tablet - Bulk Powders
Contain the active drug in a small powder paper or foil envelop. The patient empties the envelop into glass of water or juice and drinks the contents
Tablet - Chewable Tablets
Are flavored and are designed to be chewed
Tablet - Effervescent Tablets
Are granular salts that release gas and the active ingredient into solution when placed in water or juice
Capsules
- a solid dosage form consisting of a gelatin shell that encloses the drug
- usually swallowed whole
- tasteless and are easier to swallow than tablets
- contains powders, granules, liquids, or some combo w/ one or more active ingredients
- flavorings are not common for this dose form
Capsule - Soft or Soft-gel
Are capsules that contain liquid instead of powders inside the gelatin shell
Buccal Tablets and Gum
- placed in the buccal pouch
- between the cheek and the gum
- dissolved and absorbed by the buccal mucosa
Oral Dose Form
Delayed-release
- does not release the active drug immediately after administration
- avoid destruction in the stomach
- reduce GI upset
Oral Dose Form
Extended-release
Allows reduced frequency of dosing
Oral Dose Form
Modified Release Formulation
- delayed-release medication is not the same as extended- or controlled-release medication of the same drug
- modified-release dose forms should not be split
Oral Dose Form
Other Formulation
- long-acting, timed-release, and sustained-release dose forms
- sustained release (SR)
- extended release (XR, ER)
- continuous release (CR)
- long acting (LA)
Liquid Formulation
Solutions
A clear liquid
Liquid Formulation
Solvent
A liquid that can dissolve another substance to form a solution
Liquid Formulation
Aqueous Solution
Water is the solvent
Liquid Formulation
Suspensions
- are formulations in which the drug is not dissolved in the liquid
- suspensions should be shaken well before dispensing or administration
Liquid Formulation
Syrups
Are concentrated solutions of sucrose (sugar) in water and are thicker than water
Non-aqueous Liquid Formulations
Solutions that contain solvent other than water
- elixirs
- spirits
- tinctures
Non-aqueous Liquid Formulations
Elixirs
- are sweetened liquids that contain alcohol (5-40%)
- they are less sweet and less effective in masking taste than syrup
Non-aqueous Liquid Formulations
Spirits
Are alcoholic solutions that contain volatile oils (alcohol 62-85%)
Non-aqueous Liquid Formulations
Tinctures
Are alcoholic solutions (like spirits) but of nonvolatile substances
Liquid Formulation
Emulsions
Are solutions of oil and water based substances
- emulsifier
- creaming
- coalescence
Liquid Formulation - Emulsions
Emulsifier
Is a substance that disperses the oil in to water (w/o emulsion) or water into oil (w/o emulsion)
Liquid Formulation - Emulsions
Creaming
Occurs when dispersed droplets merge together; can be dispersed by shaking
Liquid Formulation - Emulsions
Coalescence
Is irreversible separation of the dispersed phase
Liquid Formulation
Gels
- made using a substance called gelling agents
- usually takes 12-24 hours to reach maximum viscosity
- add the active drug before the gel is formed
Unit Dose Disposable Syringes
Prefilled syringes that contain a single premeasured dose of medication and are thrown away after use
Oral Syringe
A device without a needle to administer medication to pediatric or elderly patients unable to swallow tablets or capsules
Effervescent Salts
Contain one or more medicinal agents and
- some combination of sodium bicarbonate w/ citric acid, tartaric acid, or sodium biphosphate
- release carbon dioxide gas when dissolved
Lozenges
Contain active ingredients and flavorings that are dissolved in the mouth
- also known as troches or pastilles
- generally have local effects
Dropper
- contains a small, squeezable bulb at one end and a hollow glass or plastic tube with a tapering point
- frequently incorporated into the cap of a vial or other container
- often used for otic or ophthalmic administration
gtt
Abbreviation for drops
Sublingual Administration
- designed to dissolve under the tongue and very quickly
- nitroglycerin (NTG) is the best known example of SL formulation
- advise patients to take a sip of water first and not to eat food or beverages until the drug is fully absorbed
Oral Dose Form
- capsules are preferred over tablets for patients with difficulty swallowing
- water preferred over beverages to aid in swallowing
- some dose forms are designed to be sprinkled on food when swallowing a solid is difficult
- liquid doses are swallowed more easily and are suitable for
- patients with swallowing difficulties
- small children
Advantages of Oral Route
- ease and safety of administration
- active ingredient is generally contained in powders or granules which dissolve in GI tract
- sublingual (and buccal) administration has a rapid onset (less than 5 minutes)
Disadvantages of Oral Route
- delayed onset, dose form must disintegrate before absorption
- destruction or dilution of drug by GI fluids and acid or food or drink in stomach or intestines
- not indicated in patients who have N&V or are comatose, sedated, or unable to swallow
- unpleasant taste of some liquid dose forms, must be masked by flavorings to promote compliance
- some drugs given SL or buccally have a short duration of action
- buccal route may have medicinal taste or local mouth irritation
Dispensing Oral Medications - NTG
- patients need instruction on proper storage of NTG
- SL NTG tablets should be stored in their original container (brown glass bottle)
- lid screwed on tightly to prevent loss of potency
- pillboxes should be discouraged
- refill NTG with a fresh bottle every 6 months
Rectal Medication - Suppository
- remove suppository from its package
- insert tapered end first w/ index finger for the full length of the finger
- may need to be lubricated w/ a water soluble gel to ease insertion
- refrigeration may make insertion of rectal medications easier in warm climates
Rectal Formulations
Is preferred when
- oral drug might be destroyed by acidic fluids in the stomach
- oral drug might be too readily metabolized by the liver and eliminated from the body
- patient is unconscious and needs medication
- N&V or severe acute illness in the GI tract make patient unable to take oral drugs
- the site of action is local to the rectum
Parenteral Routes of Administration
- an injection or infusion by means of a needle or catheter inserted into the body
- parenteral forms deserve special attention, complexity, potential for therapeutic benefit and danger including risk of infection
- this route of administration bypasses the GI tract
Parenteral Routes of Administration
Injection Independent
- ophthalmic
- intranasal
- inhalation
- dermal
- vaginal
- otic
Parenteral Routes of Administration
Injection Dependent
- intravenous
- intramuscular
- intradermal
- subcutaneous
- epidural
- intrathecal
Parenteral Forms for Injection
- parenteral preparations must be sterile
- parenterals are prepared using
- aseptic techniques
- special clothing (gowns, masks, hair net, gloves)
- laminar flow hoods placed in special rooms
Parenteral Dosage Forms
- IV route directly into a vein
- prepared in hospitals and home healthcare pharmacies
- antibiotics
- chemotherapy
- analgesics
- nutrition
- critical care medications
Needle Size Recommendation
- Intravenous 16-20 gauge, 1-1.5” length
- Intramuscular 19-22 gauge, 1-1.5” length
- Subcutaneous 24-27 gauge, 3/8-1” length
- Intradermal 25-26 gauge, 3/8” length
Parenteral Route
- disposable syringes and needles are used to administer drugs by injection
- different sizes are available depending on the type of medication and injection needed
- IV infusion can provide a continuous amount of needed medication without fluctuation in blood levels of other routes
- infusion rate can be adjusted, provides more or less medication as the situation dictates
Intravenous Formulation
- administered directly into a vein
- takes about 20 seconds to circulate throughout the body
- aqueous solutions are the most common formulation
- syringeability
- injectibility
Syringeability
The ease with which a material can be drawn from container into a syringe
Injectibility
The ease of flow when a material is injected into patient
Intravenous Injections or Infusions
Intravenous injections are injected directly into veins and are administered at a 15-20 degree angle
Intravenous Administration Devices
Infusion
- gradual IV injection of a volume, usually 500-1000ml, of fluid into a patient
- e.g. dextrose in water 5% (D5W), 0.9% sodium chloride in water (NS)
- solution bag has two ports: an administration set port and a medication port
Intravenous Administration Devices
Infusion Pump
- ensures consistent and controlled delivery rate
- patient controlled analgesia (PCA) are pumps for self administration or pain medication
Parenteral Route Advantages
- IV route is the fastest method for delivering systemic drugs, preferred route in an emergency situation
- can provide fluids, electrolytes, and nutrition; patients who cannot take food or have serious problems w/ GI tract
- provides higher concentration of drug to bloodstream or tissues; advantageous in serious bacterial infection
Parenteral Route Disadvantages
- formulation is limited to solutions, suspensions, and emulsions
- has to be sterile (bacteria free)
- pH must match body fluid’s using buffer system
- limited volume should be used to avoid pain and necrosis
- higher cost, drug and auxiliary devices
- required skilled personnel to administer them
- most difficult to remove once administered if there is an adverse or toxic reaction
- requires a needle for injection
- potential for additional adverse events, e.g. infection or clots
IV Formulation Complications
- thrombus formation
- phlebitis
- air emboli
- particulate material can include small pieces of glass that chip from the product’s vial or rubber pieces from the stopper
Intramuscular Injections
- care must be taken with deep IM injections to avoid hitting a vein, artery, or nerve
- in adults, IM injections are given into upper, outer portion of the gluteus maximus
- for children and some adults, IM injections are given into the deltoid muscles of the shoulders
- depot - the area in the muscle where the formulation is injected
Intramuscular Injections Needle
- typical needle is 22 to 25 gauge, 1/2 to 1 in needle
- IM injections are administered at a 90 degree angle
- volume limited to less than 3 ml
Advantages and Disadvantages of the IM Route
- IM and subcutaneous routes of administration are convenient ways to deliver medications compared with IV route
- onset of response of medication may be slower
- duration of action can be longer
- practical for use outside hospital
- used for drugs which are not active orally
- injection site needs to be “prepped” using alcohol wipe
- correct syringe, needle, and technique must be used
- rotation of injection site with long-term use to prevent scarring and other skin changes and can influence drug absorption
Subcutaneous Injection
- administer medications below the skin into the subcutaneous fat
- outside of the upper arm
- top of the thigh
- lower portion of each side of the abdomen
- not into grossly adipose, hardened, inflamed or swollen tissue
- often have a longer onset of action and a longer duration of action when compared w/ IM or IV
Subcutaneous Injection Needle
- given at a 45 degree angle
- 25-26 gauge needle, 3/8 to 5/8 in length
- no more than 1.5 ml should be injected into the site; avoids pressure on sensory nerves causing pain and discomfort
Subcutaneous Injection Insulin
- given using 30-32 gauge short needles, special syringe that measures in units
- keep insulin refrigerated
- check expiration dates frequently, open vials should be discarded after 28 days
- vial of insulin is mixed by rolling between the hands and never shaken
- rubber stopper should be wiped w/ an alcohol wipe
Intradermal Injection
- given into capillary-rich layer just below epidermis for
- local anesthesia
- diagnostic tests
- immunizations
Examples of Intradermal Injections
- skin test for TB, typical site is upper forearm, below area where IV injections are given
- allergy skin testing
- small amounts of various allergens are administered to detect allergies
- usually on the back
Implants (or Pellets)
- are dosage forms placed under the skin by means of minor surgery
- used for long-term, controlled release of medications
- enhanced patient compliance and convenience
- complications at the site of insertion have limited use
- e.g. viadur, duros, supperlin LA
Plasters
Are solid or semisolid preparations that adhere to the body
Topical Routes of Administration
- the application of a drug directly to the surface of the skin
- includes administration of drugs to any mucous membrane:
- nose
- ears
- vagina
- urethra
- colon
- lungs
Ophthalmic Medication
- administered for local treatment
- must be at room temperature or body temperature before application
- have to be sterile; only preparations w/ preservatives can be repeatedly used
- major problem is the immediate loss of dose by natural spillage from eye and about 80% of a dose will be lost from the eye overflow
- unused ophthalmic mediations should be discarded 30 days after container is opened
- manufacturer expirations do not apply once opened
Ophthalmic Ointments Formulation
- tend to keep the drug in contact with the eye longer than solutions
- most ointments are made of mineral oil and white petroleum and have a melting point close to body temperature
- ointment cause blurring of vision and should be applied at night
Ophthalmic Administration (Preparation)
- before application, patient should wash hands, prevents contamination of application site
- tube or dropper should not touch the application site, medication may become contaminated
- only sterile ophthalmic solutions or suspensions should be used in the eye
- ear drops can never be used in the eye, eye drops can be used in the ear
Ophthalmic Administration
- patient’s head should be tilted back
- after administration, patient should place a finger in the corner of the eye, next to the nose to close the lacrimal gently, prevents loss of medication through tear duct
- patient should also keep the eyes closed for 1-2 minutes after application
- when multiple drops of more than one medication are administered, the patient should wait 5 minutes between different medication
- if an ointment and a drop are used together, the drop is used first, wait 10 minutes before applying the ointment
Contact Lenses
-if patient is allowed to wear contact lenses, the lens should be put in the eye 5 minutes after the solution is used
Ocular Inserts
- Ocusert is an ocular insert designed to deliever pilocarpine at a controlled rate for up to 7 days
- lenses placed in a solution containing a drug and the lenses absorb the drub solution
