Drug Delivery Flashcards by Adam Moughal

What does a drug formulaton involve

Drug delivery system formulated
Allows immediate or delayed onset
Avoid pre/systemic metabolism
Allows selective targeting of tissue

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What determines the drug delivery system we use?

dose of the drug
frequency of administration
timing of administration

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What factors do we consider to determine the dose?

Renal function
Hepatic function
Consider age and weight
Consider disease to be treated
Consider drug toxicity
Give a starting dose and increase dose to achieve the desired effect

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What is the most frequently used dosage route

Oral medication

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What determines the speed of absorption of solutions and suspensions?

Gastric emptying - most rapid from the small intestine

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What is the benefit of Solutions and Suspensions?

Easier for patients with swallowing difficulties

absorbed rapidly

Given via a naso-gastric or PEG tube

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What is a suspension?

Dispersions of coarse drug particles in a liquid phase

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What are suspensions useful for?

Drugs which are insoluble/unpalatable

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What is the most commonly used formulation?

Tablets and capsules

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What is the rate limiting step for capsules and tablets?

Tablet breakdown (dissolution)

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What are the advantages of the tablets and capsules?

Convenience
Accuracy of dose
Reproducibility
Drug stability
Ease of mass production

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What is the effect of the enteric coated tablets?

Delays disintegration of tablet until it reaches small intestine
Protects drug from stomach acid
Protects stomach from drug

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What is the benefit of Prolonged or Delayed Release Formulations?

Most disorders required prolonged therapy
Maintains drug levels within a therapeutic range
Reduces the need for frequent dosing
Compliance is improved
Improved nursing and doctor compliance

Longer time course of drug in body

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What are the advantages of prodrugs?

Prolonged duration of action

Avoidance of drug degradation in the gut

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What is a prodrug reliant on?

Liver function - metabolism activates the drug

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What is Buccal and Sublingual Administration ideal for?

Ideal method for drugs which have extensive pre-systemic or first pass metabolism

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How would you take sub-lingual drugs?

Sublingual tablets are small and dissolve slowly under the tongue or in the buccal cavity(behind lips in front of teeth)

What is the rectal route useful for?

Useful in the young or old
Patients who are unable to swallow
Bypass pre-systemic metabolism

What is the vaginal route used for?

Local disease

What are the advantages of injection based drug delivery?

Provide fast systemic effects bypassing first-pass metabolism
Drugs administered in unconscious or comatose patients
Drugs having short half-life can be infused continuously

When is intravenous administration used?

When:

A rapid onset of action is required
careful control of Plasma levels is required

A drug has a short half-life

How may IV formulations be given?

Rapidly
Slowly to prevent toxic effects
Continuous infusion to ensure accurate control of blood levels especially when a drug has a narrow therapeutic index

Describe what an Intramuscular Injection is?

An injection of the drug is given into the muscle mass

Describe the type of solution given in intramuscular injection

The drug may be insoluble
Formulated in an oil base

What is the benefit of intramuscular injection?

Allows a more sustained duration of action up to months

What are the advantages of subcutaneous injection?

Easy to use and bypasses need for venous access

How does transdermal drug delivery enter the systemic circulation?

The drug crosses skin surface by diffusion by percutaneous absorption

What does transdermal drug delivery avoid?

Bypasses first-pass hepatic metabolism

What is percutaneous drug administration?

Creams, Ointments and Skin patches Drugs can be administered to the skin to achieve a local effect i.e steroids or a systemic effect i.e HRT or nitroglycerin

What is the benefit of skin patches?

Possible to obtain controlled, sustained blood levels of the administered drug such as nicotine, nitroglycerin, opiates, HRT, contraception

When are drugs administered by inhalation?

Delivers drugs directly to the lung for local effect To achieve a systemic effect I.e anaesthetics

What are the advantages of inhalation?

``` Drug delivered directly to site of action Rapid effect Small doses used Little systemic absorption Reduced adverse effects ```

What are the disadvantages of inhalation?

Patient education is essential

How do monoclonal antibodies act?

Bind to cancer specific antigen and induce an immunological response to cancer cells

What can Monoclonal antibodies be used to deliver?

Toxin, cytokine or other active drugs

What is the purpose of liposomal drug delivery?

Altered pharmacokinetics results in reduced toxicity with enhanced efficiency There is reduced distribution of drug to sensitive tissue

What is another method of increasing the precision in targeting of a drug as well as reducing the toxicity?

Nanoparticle based drug delivery - makes the drug more effective and reduces the chances of possible side-effects

What are nano erythrosomes and what are their applications?

Erythrocytes that can carry, proteins, enzymes and macromolecules Used in the treatment of liver tumour, parasitic disease and enzyme disease

What is the vector for the genetic transfer system involving the delivery of therapeutic genes to target cells?

Viruses

What are antibody drug conjugates

Monoclonal antibodies attached to an active drug with a linker