Diabetes Lecture 3: Parenteral Drug Delivery Flashcards Preview

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Flashcards in Diabetes Lecture 3: Parenteral Drug Delivery Deck (36):

What does parenteral mean

Method to deliver the drug directly to the blood outside of GI tract


What does Ka, Kd, Km and Ke stand for

Ka- absorption

Kd- distribution

Km- Metabolism

Ke- excretion


What are the advantages of injection

Rapid and complete absorption

Able to predict the pharmacokinetic profile of drug: control drug and frequency

Useful in unconscious patient, uncooperative patient, nausea and vomiting patient, unable to swallow

Useful for giving small dose


What are the disadvantages of injection

Aseptic precautions must be followed

Expensive to manufacture

Once administered, impossible to remove from blood stream

Pain and infection at site of injection


What are the different angles for the intramuscular, subcutaneous and intradermal

Intramuscular: 72 or 90 degrees

Subcutaneous: 45 or 90 degrees

Intradermal: 15 degrees


Why shouldn't you administer larger volume intravenous route into the vein at a fast rate

Can lead to sudden osmotic pressure and electrolytes can lead to risk of shock or acute renal failure


What complications are associated with IV delivery and describe them

Air embolism- injection of air bubble to vessel can prove fatal if it reaches brain

Thrombosis- formation of clot in blood vessel

Haemolysis- breakdown of red cells lead to relate of haemoglobin

Phlebitis- inflammation of vein wall due to irritation from formulation

Extravasation- leakage of the injection from the vein into surrounding tissue


What are the typical areas of intramuscular injection and advantage it has

Vastus lateralis

Quick onset of action


What is subcutaneous injection route

Used into the fat layer
Beneath dermis and epidermis and above muscle tissue: typically at arm, abdomen or legs


Give examples of subcutaneous injection use

Local anaesthetics: lidocaine 5% with adrenaline

Used to administer antigens or vaccines (small pox)


How does the administer subcutaneous drug gain assess to the blood stream

Absorbed into the blood vessels directly, but subcutaneous tissues often adipose and poorly perfused

Interstital fluid is collected by lymphatic capillaries and these drain into the regional lymph nodes and into bloodstream


What are the four insulin delivery methods available (devices)

Insulin syringe- vial

Insulin Pen- can carry insulin discreetly with cartridges and a fine needle

Insulin pump or pod- worn on belt, has needle inserted under skin, pump provides basal insulin throughout day and bolus doses at meal times

Jet Injector- sends spray of insulin through skin by high pressure


Describe the use of rapid acting insulin and give examples

Acts within 10 to 15 minutes, used to treat high blood sugar level to match or cover a rise in food glucose levels following intake of food

Referred to as bolus insulin

Examples: Homolog, Novolog, Apidra


Describe the use of short acting insulin (regular)

Used like rapid acting insulin- used to treat high blood sugar level or cover a rise in food glucose levels following intake of food

Has a longer duration of acting and delayed peak

Referred to as bolus insulin


Describe the use of intermediate and long acting insulin and provide examples

Provides basal insulin concentrations and doses that are adjusted based on pattern of blood glucose

Not used for acute treatment of high blood glucose and generally not given before meals

Referred to as basal insulin

Controls the blood glucose in a fasted state

Intermediate example: NPH

Long acting example: Glargine (lantus) and Deter (Lever)


What are the types of insulin normally used in pumps

Aspart (Novolog)

Lisper (Homolog)

Glulisine (Apidra)


Describe what basal insulin is

Steady drip of insulin that matches glucose release by liver

Meets body's basic energy needs


Describe what bolus insulin is

Given to cover carbohydrates consumed in meals and snacks

Used to correct high blood glucose levels


What is Intrathecal delivery

Injection into the subarachnoid space to reach cerebrospinal fluid


What is epidural delivery

Delivery of drug into the dural membrane surrounding the spinal cord


What are the three requirements for parenteral drug delivery


Pyrogen free- endotoxin that induces fever (produced by deactivation of bacteria)

Homogenous- delivers reproducible dose, physically and chemically stable


What must you consider when formulating an intravenously delivered drug


Small fragments of dust and glass or rubber excluded

Small volume (100ml or below) must be formulated at range of 4 to 10 (considerably hypo/hypertonic)

Large volume- closely matched to properties of blood- pH rarely outside 6 to 8 limit


Define plasma extender

IV parenteral infused via peripheral vein with closely matched tonicity


What are suitable vehicles for injection

Water- has to be pure and sterile

Non aqueous vehicles:
Used for non water soluble APIS
Typically are oils


State some co-solvents that can be used in formulation

Soybean Oil
Castor oil


State some surfactants that can be used

Tween 80
Sorbitan monooleate
Tween 20


Which parenteral drug delivery should preservatives be avoided and give an example of preservatives

AVOIDED IN: single dose IV

Phenol (0.25 to 0.5% w/v)
Chlorocrasol (0.1 to 0.3% w/v)


How do you correct hypotonicity



Give examples of commonly used buffers

Acetic acid/sodium acetate

Citric acid/sodium citrate

Sodium phosphate and disodium phosphate


How do you render a solution isotonic

Addition of Dextrose or sodium chloride solution to increase osmotic pressure of solution


How do you change viscosity and what do you add

Change when adding polymeric stabiliser

example: PVP or aluminimum stearate


What are the advantages of increasing viscosity in a dosage form


Steric hinderance

Decrease flocculation of suspensions



What are the steps involved in intramuscular deliver

release of the drug from the dosage form into intracellular fluids

Absorption from intracellular fluids into the blood and lymphatic system

transport from the local blood volume into the general circulation



What are the advantages of injection in general capillary membrane

It is highly permeable and not rate limiting


What are the key points you have to know for release rate: hydrophobic/phillic, ionisation and protein bound

Highly hydrophobic will not dissolve in the intracellular fluid

Strongly ionised or very water soluble- will not cross capillary membrane

Strongly protein bound will be slowly absurd as activity in solution is reduced


What is intramuscular delivery contraindicated in patients with cardiac failure

Absorption will be extremely slow as muscle perfusion will be small