Routes Of Administration & The Absorption of Drugs Flashcards by Gen Parkinson

Why are synthetic drugs often better than medicine obtained from nature? (e.g. plants, animals, microorganisms or the body itself (biologics))

They are widely available and more specific.

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What are the 5 rights associated with drug administration?

Right Patient
Right Dose
Right Route
Right Time
Right Documentation

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List 2 benefits of oral administration:

Convenient for patient

Absorption from small intestine (large surface area)

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Name 6 disadvantages of oral administration:

Not appropriate for all patients.
Absorption is variable (must be lipid soluble)
Absorption can depend on the stomach contents (acid/alkali)
Rate of gastric emptying
Degradation in stomach
First pass metabolism

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What is drug disposition?

Comparing what the body does to the drug with what the drug does to the body.
After intake, absorption and distribution, drug-cell interaction competes with metabolism and excretion.

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How are drugs degraded in the stomach and what effect does this have on bioavailability?

Parietal cells in the stomach secrete HCl (hydrochloric acid) whilst chief cells secrete digestive enzymes.
This gastric acid breaks down the drug, reducing in a low bioavailability - a low dose of drug reaching the circulation

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What is first pass metabolism? What effect does this have on bioavailability?

Otherwise known as the hepatic first-pass effect, this refers to the extent to which the liver can metabolise the drug. If the drug can be rapidly metabolised this decreases bioavailability.

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List the steps of how the drug gets into the circulation via oral administration:

Oral/enteral Administration.
Absorption via stomach and intestine (subject to degradation in stomach)
Portal vein to liver (subject to first pass metabolism)
Hepatic vein then Vena Cava

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Name 2 benefits of topical administration:

Convenient for patient
Poorly absorbed (minimising overdose risk)

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What is the main disadvantage of topical administration?

Negative effect on the skin e.g. hydrocortisone thins the skin

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What is a good way to remember what topical administration is?

TOPical - creams and lotions go on ‘top’ of the skin.

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Name 3 advantages of Transdermal administration:

Long acting
Useful when want low blood levels for long periods of time
Suitable for many patient groups

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What are 4 disadvantages of transdermal administration?

Potential adverse skin effects
Variable absorption
Drug must be very lipid soluble
Drug must be very potent

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What are 2 advantages of rectal administration?

Local or systemic effect

Useful for patients who are vomiting or unable to swallow

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Name 4 examples of drugs that can be administered rectally:

Analgesics
Diazepam
Prednisolone
Anti-fungals

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What is a drawback of rectal administration? (Other than discomfort)

Trained staff are needed to administer the drug

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List 2 advantages of the inhalation method of administering drugs:

Rapid changes in the plasma concentration of the drug
(due to large surface area of lungs and good blood flow in this area)

Local/systemic effect

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What is the main disadvantage of the inhalation route?

Difficulty in ensuring the drug reaches site of action

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Give 4 examples of drugs that can be administered via inhalation:

halothane
nitrous oxide
GTN
salbutamol

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What are the 6 routes of parenteral administration?

Give an example for each route.

Intravenous: vein - heparin          
Intramuscular: muscle - pre-meds
Intradermal: skin - local anaesthetic
Subcutaneous: lower in skin - insulin
Intrathecal (into subarachnoid space) - chemotherapy
Epidural - nerve blockers

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What is transdermal administration?

ACROSS the skin - e.g. nicotine or HRT patches

A reservoir of drug diffuses across the skin

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Name 4 advantages of the parenteral route of administration:

Rapid action
Bypasses stomach and liver
Lower dose is required
Allows for patient controlled analgesia through syringe drivers

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What are 4 disadvantages of the parenteral route?

A trained person is required to administer the drug this way
Extreme care is required
Accidental overdose can be easy
Painful (I.M. injections)

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What is an excipient?

An additional ingredient added to a drug that allows it to spread and transport in the body

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What 2 things is a medicine made up of?

An active drug and excipients

Name 3 types of drug formulation:

Tablet, capsule, granule, powder, gel, emulsion, implant, gas, spray etc...

What 2 things can the formulation of a drug affect?

Bioavailability - to absorb quicker | Duration of therapeutic effect (sustained release - lots of layers)

List the 4 types of oral formulation of drug in the order of dissolution rate (fastest to slowest):

``` Solutions Suspensions Powders Capsules Tablets ```

From where are orally administered drugs absorbed?

Stomach | Small intestine

Can water soluble drugs cross the cell membrane in the gut?

What types of drugs can diffuse across the cell membrane in the gut?

Lipid-soluble

List the 4 ways lipid soluble drugs can diffuse from the gut into the blood:

Passage through water channels (this is passive) Endocytosis Passive diffusion Facilitated or Active Transport

What is endocytosis?

An energy using process where cells absorb the drug molecules by engulfing them

Outline facilitated transport

The drug moves DOWN the concentration gradient Proteins provide channels NO ENERGY is expended Saturable and selective Competitive inhibition by other substrates

Outline Active Transport

Drug moves AGAINST the concentration gradient ENERGY is expended Saturable and selective Competitive inhibition

Name one drug that passes across the membrane using active transport:

Levodopa Methyldopa Lithium

What types of tablet are available?

Orodispersible, effervescent and dispersible

How are tablets, capsules, elixirs/syrups, emulsions and linctus administered?

Orally

What are the two different routes of oral administration? (other than swallowing)

Sublingual | Buccal

What type of oral medicine is: convenient to use, can provide an accurate dose, can be enteric-coated or have sustained release and Must not be bitten or chewed, not be broken, caution to what liquid it should be taken with?

Tablets

How are drugs administered orally that are bitter, but end up being large and coated with a hard gelatin coat?

Capsules

Sprays (such as GTN) and uncoated tablets can be rapidly absorbed through mucosa (under the tongue). What is this route called?

Sublingual route

What is the name of the route where tablets are placed between the gums and the cheek (upper lip), for rapid absorption? It is good for antiemetics but increased risk of dental caries.

Buccal Route

What is a compound tablet?

A tablet containing two or more medicines

What are elixirs and syrups examples of?

Liquid medicine

Why may elixir medicines not be suitable for kids?

Alcohol base

What is an emulsion?

A mixture of two liquids. It must be shaken well to ensure patient gets the right amount of both.

You have to shake emulsions well before dispensing them. What problems may occur however even after doing this?

Inaccuracy and danger of liquids separating out

What is a linctus?

A sweet, syrupy liquid, often mixed with aromatics as a soothing medication. e.g. cough medicine

What type of liquid medicine can be difficult to measure due to its viscosity and can have a sticky bottle?

Linctus'

Why must you always pour liquid medicine AWAY from the label?

So if it spills you can tell what the drug is - the label isn't damaged.

Should you shake or agitate all liquid medicines?

Yes

How should medicines be stored? | 5 answers

``` original packaging locked cupboard or meds trolley if belong to the patient - bedside locker locked fridge room temperature away from sunlight ```

When administering a drug to a patient, where should you document this and where can it be found?

Prescribing and recording sheet at patient bedside or document trolley

When administering medicine, your hands should be clean, the patient should be upright and you should witness the medicine being taken. What else should you try to get the patient to do?

Put the medicine in mouth themselves

What should you do with rejected medicine?

Retain it

What does 'para' and 'enteral' mean in the word paraenteral?

``` Para = around Enteral = the gut ``` AVOIDING THE GUT - not oral

What are the 6 routes of parenteral administration?

``` Percutaneous Inhalation Subcutaneous Intraarticular/synovial Intramuscular Intravenous ```

What is the method called where drugs are absorbed through intact skin, body cavities or mucous membranes? (other than topical etc - begins with p)

Percutaneous

What is the route of admin that involves infusion via the lungs?

Inhalation

What is the route of admin that involves an injection under the skin?

Subcutaneous

What is the intra articular/synovial route of admin?

Injection into a joint

Define intramuscular:

Injection into muscle

Define intravenous

Injection into a vein

What 5 reasons would you use parenteral administration for?

``` Faster onset of action Nil by mouth Drug digestible Long term release (depot injection) Other routes impaired/contraindicated ```

Intramuscular and subcutaneous routes provide a more ............. release?

controlled

What can localised routes of administration minimise?

Unwanted effects

Name 5 disadvantages of parenteral routes of admin:

Additional training and competence required Costly Painful Aseptic Technique required for protection Additional tech/professional support often needed

What are topical and transdermal routes of admin examples of?

Percutaneous routes

What are drops, creams, ointments, pastes, gels and lotions examples of? (how are they applied)

Topical routes of admin

What are patches that allow the slowed absorption of drug to the blood supply below the dermis called? (in terms of route of admin)

Transdermal

Inhalational, sublingual/buccal, suppositories (low end), enemas (liquid in lower bowel) and pessaries (vagina) are administered through b.......... c........... They are not the most absorbable places but what do they avoid?

body cavities | avoid first pass effect

Where is a subcutaneous injection placed?

Under skin - in the fat layer before the muscle

Which injection risks hitting a nerve or important vessel?

Intramuscular

Which injection is the most risky/irreversible?

Intravenous

What do you call the name of the injection into joints to relieve arthritic pain?

Intra articular/synovial

What is an intrathecal injection?

Into CSF

What is an intracardiac injection?

Into the heart

Obvious disadvantages of me include fear, pain and bruising. | I can also cause abscess, tissue necrosis, cellulitis, granuloma and lipohypertophy. What am I?

An injection

What things can minimise the disadvantages of injections?

The Rs Handwashing/infection control Protocols Talking to patient to distract

What holds a single dose of parenteral medication that may be a plastic or glass container?

Ampoule

What may hold single or multi doses of parenteral medication that will have a sealed rubber cap to allow multiple doses to be withdrawn? (change needle in between uses to keep it sharp)

Vial

What is the process whereby a drug comes as a powder and needs a solvent such as sterile water or a normal saline solution to be mixed with it? What should you do if there are no instructions?

Reconstitution | Contact pharmacy - must use right solvent

Where might we withdraw small amounts of fluid, allergy testing and do TB screening?

Inner lower arm

When doing TB screening, allergy tests or withdrawing small amounts of fluid from the inner lower arm, what do we call this route?

Intradermal injection/in the skin - second layer

What site are we likely to inject 0.5ml-1ml of medications such as insulin, heparin and vaccines?

Subcutaneous

When injecting the IM Deltoid, which part should we inject and what is its limitation?

Upper 1/3 to avoid nerve | Only up to 1ml before really painful

What is the IM Dorsogluteal? | What is its advantage to injecting here?

Upper outer bit of bottom | Avoid nerve and major blood vessels here

Other than the deltoid and dorsogluteal, name to other IM injection sites:

top of leg - vastus lateralis or rectus femoris (often after surgery but it is painful) side of hip - ventogluteal

What should we try and do when using needles in regard to size?

Use smallest possible. | No bigger than 2ml

Which type of injection uses a: 25 to 27 gauge needle less than 0.5ml of drug

Intradermal | smallest gauge range

Which type of injection uses a: 23 to 28 gauge needle 0.5ml to 1ml of drug

Subcutaneous

Which type of injection uses a: 18 to 23 gauge needle 0.5ml to 3ml of drug

Intramuscular LOW in depth so lowest gauge in teens

What are the 4 main objectives of I.V. therapy?

Maintenance and restoration of fluid and electrolyte balance (some can't take by mouth) Delivery of parenteral nutrition Transfusion of blood products Medication and chemotherapy

In I.V. therapy, what type of infusion is continuous over 12-24 hours, and may use isotonic, hypotonic or hypertonic fluid?

Large Volume Infusions (e.g. for hydration)

What type of I.V. is for a short period of time (2-3minutes)?

Rapid injection - e.g. antibiotics

What type of I.V. lasts for a period of 30-60minutes and is done every 4 hours?

Intermittent Infusions e.g. antibiotics that need to be delivered slowly

What is the name of a short catheter that is inserted through the skin into a peripheral vein? Where are these usually inserted?

Peripheral Cannula Usually the arm and hand. Extreme cases foot and children sometimes scalp

What is the name of a catheter placed in a large vein?

Central Venous Catheter

Where is the internal jugular vein?

Neck

Where is the subclavian vein?

Chest

Where is the femoral vein?

Groin

Name 3 types of catheter: | TIP

Tunnelled Catheter (Hickman Line) Implanted Port Peripheral Inserted Central Catheter (PIC)

Is the jugular (neck) or tunnelled catheter (chest) used more now? Why?

Tunnelled. | Can cover with clothes, leave for months, safer

Where is the connector of an implanted port?

Under the skin, so not loose like a Hickman/Tunnelled catheter. Special needles are used for these to go straight into blood stream

Where is the PIC close to?

The heart. It can irritate the atrium and it is important to check for inflammation.

What do we flush I.V. lines with to prevent blood clots on the end of the catheter?

Saline

Name 4 I.V. fluids: | BIGS

Isotonic saline Balanced Crystalloid solutions Glucose and glucose salines Synthetic colloids

What 2 bits of equipment (other than the catheter and bag) can be used to administer I.V. fluids?

Tubing with special chambers | Electronic Pump

Name 3 complications of I.V. Therapy:

Infection (break to skin, organisms into site = swelling, fever, septicaemia) Phlebitis - irritation of the vein caused by infection Tissue Infiltration - fluid ends up in surrounding tissue rather than vein