Part 6 Flashcards by amanda kastel

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Explain why suspensions have a higher dissolution and absorption rate than powders

suspensions are FINE particles suspended in a liquid vehicle. Therefore, the surface area is higher increasing the dissolution rate

POWDERS are GRANULES. They are larger and have a smaller surface area than fine particles

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rank the following according to dissolution rate:

tablet
capsule
suspension
powder

highest: suspension>powder>cap>tab

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IN ORDER FOR ABSORPTION TO TAKE PLACE….

the drug must be in solution

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What is the term for a tablet becoming granules

disintegration

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what is the term for granules becoming fine particles

deaggragation

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Absorption of drugs via oral route can occur anywhere between….

the mouth and the rectum

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The highest absorption occurs in…..

the alimentary tract (small intestine)

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What are the parameters affecting absorption

-gastric emptying time

-large volume of water

-degree of drug ionization

-drug’s interaction

-controlled release

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explain how gastric emptying time affects absorption via the oral route

-the presence of fatty foods SLOWS gastric emptying. fatty foods have the most slowing effect, then proteins, then carbohydrates

-if you lie on the right side when bedridden, the pylorus will sit right on top of the stomach, raising gastric emptying time

-some drugs such as morphine have a quieting effect on the GI tract and can slow movement, increasing gastric emptying time

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the higher the gastric emptying time, the _____ the absorption

slower

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Explain how large volume of water affects the absorption rate

If a medicine is taken with a large volume of water (8 oz = 1 glass), gastric emptying is facilitated and absorption is increased

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explain how the degree of ionization affects absorption

the pH of the GI tract increases progressively along its length from pH 1 in the stomach to pH 8 at the far end of the intestines.

pH has a definite bearing on the degree of ionization of most drugs, and this affects:

-lipid solubility
-membrane permeability
-absorption

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As a general rule, weak acids are largely ________ (ionized or unionized) in the stomach

unionized

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Since weak acids are largely unionized in the stomach, what can you say about their absorption here?

weak acids are absorbed fairly well from here

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Are weak bases ionized in the stomach? what can you conclude about the absorption of weak bases in the stomach?

weak bases ionize in the stomach, and are NOT readily absorbed there

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if an antacid drug is taken, what would occur?

alkalinization would occur.
this would decrease the gastric absorption of weak acids and increase the gastric absorption of weak bases

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Do strong acids and strong bases readily absorb? explain

NO — due to their high degree of ionization

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WHY does the small intestine serve as the major absorption pathway for drugs?

because of the suitable pH and the large surface area available along its 20 foot length
pH is about 6.5, thus weak acids and weak bases are well absorbed from the intestinal surface

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most drugs are…

weak acids or weak bases

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Explain how the drug’s interaction can affect absorption

if a tetracycline is taken with milk, a complex will be formed. this will reduce solubility of the drug and bioavailability

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What is the measure of a degree of ionization

the hendersen hasselbach equation

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A drug has to be (ionized or unionized) to cross the cell membrane

UNIONIZED

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What can you say about the solubility of sublingual drugs

they are EXTREMELY SOLUBLE and rapidly dissolving

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what can you say about the concentration of sublingual drugs

they have a HIGH drug concentration and avoid the first pass effectr

Does swallowing have to occur for a sublingual drug

What is a major advantage of the rectal route

~50% avoids the first pass effect (bypasses hepatic vein and the liver enzymes --- metabolization) liver enzymes destroy the drug before it reaches circulation

are drugs given rectally for their local effects or systemic effects?

both ointments for local effect suppositories for systemic effect or local effect (hemrrhoids)

soluble drugs given rectally are usually absorbed by...

rectum and the colon

What are some advantaged of the parenteral route

-rapid absorption in case of emergency -more predictable -smaller doses -- bc it's put directly into circulation -useful for uncooperative or unconscious patients -pts who are unable to take oral meds

What are some disadvantages of the parenteral route

-once injected, there is no retreat (concern if toxic, overdose) -frequent dosing -more expensive (must be sterile, trained personnel usually do it)

Name 3 dosage forms for parenteral route

MUST BE STERILE (no bacteria): solutions suspensions pellets

explain how solutions given by parenteral route can vary

-vegetable oil or water -vegetable oil is likely to be more slowly absorbed than a solution with water --control of absorption

Name 4 routes of administration for the parenteral route

-intravenous -subcutaneous (administered to fat layer) -intramuscular -intradermal (administered to dermis)

What are the 2 types of intravenous injections and explain them

bolus ---- single, small volume injection infusion --- slow, large volume

Intravenous injections are _____ solutions. WHY

aqueous. there can be NO PRECIPITATION within the circulatory system. this could produce emboli (blocked artery)

Why might a fat emulsion be used in an intravenous injection?

for caloric sources. Glucose doesn't cut it for some patients

Can a suspension be used for an intravenous injection? Why or why not

NO The particle size of the drug CANNOT BE BIGGER THAN AN RBC. (7 micrometers). They are larger than that in a suspension

Subcutaneous injections are injected into..... and what volume

loose subcutaneous tissue at a volume of 2mL or less

what are some sites of subcutaneous injection

forearm, upper arm, thigh

Do subcutaneous injections HAVE to be aqueous solutions?

no! they can also be suspensions or pellets

Where are intramuscular injections given? Why?

DEEP INTO SKELETAL MUSCLES such as gluteal or lumbar muscles This is done to avoid hitting a nerve or a blood vessel

Do intramuscular injections HAVE to be aqueous solutions?

no---- they can be aqueous or oleaginous solutions or suspensions

What does oleaginous mean

oil based

What is an advantage of intramuscular injections

Certain drugs, because of their low solubility, provide sustained drug action after an intramuscular injection ex: penicillin G benzathine provides 7-10 days of effect

is dissolution slower in aqueous or oleaginous solutions

oleaginous

where are intradermal injections given and at what volume

in the corium (dermis) of the skin given at VERY SMALL VOLUMES (~0.1mL) sites: arms and back

when are intradermal injections given?

tuberculin or allergy testing

does the epicutaneous route of administration give local or systemic effects?

both

Drug absorption via the skin is enhanced if...

-it is in solution -if it has a favorable lipid/water partition coefficient -if it is a nonelectrolyte

Drugs that are applied by the epicutaneous route (on the surface of the skin) are absorbed by....

-pores -sweat glands -hair follicles -sebaceous glands

Name some drugs applied to the skin surface for percutaneous absorption and systemic action (disk or patch)

-nitroglyicerin -estradiol -clonidine -scopolamine -Fentanyl -nicotine

Are pharmaceutical preparations applied to the skin usually for systemic or local effects?

usually local (antiseptic, antifungal, antinflammatory, etc)

what are local applications used for

antiseptics antifungal anti-inflammatory local anesthetic skin emollients protectants

What are the potential dosage forms for LOCAL applications via the epicutaneous route

Semisolid dosage form (ointment, cream, paste) solid dry powder (aerosol sprays) liquid dosage form (solutions and lotions)

Ointments are a _____ dosage form

semisolid

The ointment base is either...

hydrophobic or hydrophilic

is there a universal ointment base for all drugs?

Are ointments greasy or non greasy

greasy

Creams are a ______ dosage form

semisolid

creams are _______, meaning they contain oil and water

emulsions

differentiate between creams and ointments

creams are less viscid (sticky), are lighter than ointments, and are nongreasy

Pastes are a _____ dosage form

semisolid

Which has the MOST solid substance ---- creams, ointments, or pastes?

pastes

Since pastes are more solid than ointments, what can you say about their action

pastes are stiffer and less penetrating. Therefore, they are not so much used for therapeutic effect as for protective action (absorbing discharge from skin lesions)

if therapeutic effect is the main concern which will be the preference ---- creams, ointments, or pastes

creams or ointments -- NOT PASTES

Powders are a _____ dosage form

solid

powders can be used ___ or ___

orally or locally

What can you say about the particle size of the powder

the powder should NOT BE GRITTY AND CAUSE IRRITATION ON THE SKIN

Give examples of when a local topical powder would be prescribed

for diaper rash, chafing, and athlete's foot

Lotions are a ____ dosage form

liquid --suspension of solid drug (VERY SMALL PARTICLES) in an aqueous vehicle

are lotions greasy or nongreasy

nongreasy

lotions are mainly used for.....

large skin applications

why is lotion the choice when a large skin area is concerned?

because lotions are less viscous than the other options (after all, it's a liquid dosage form) and is thus easier to spread

name 4 dosage forms for the ocular route

-sterile solutions -sterile suspensions -sterile ointments -delivery systems

between optic ointments, suspensions, and solutions, rank them according to how long they stay on the surface of the eye

longest --- ointments second --- suspensions shortest ----- solutions

for both the ocular route and nasal route, the solutions must be ___. why?

ISOTONIC to reduce irritation to the local tissue

Name 4 dosage forms via the nasal route

solutions --- decongestants sprays inhalers ----- decongestants delivery systems

Does the rectal route have predictable drug release and absorption?

NO --- parenteral route does

is there an intranasal route for nitroglycerin

NO there is.... sublingual buccal oral ointment transdermal infusion

does passive transport mean that the drug is highly lipid soluble?

Part 6 Flashcards

(82 cards)