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Pharm304 > Veterinary drug delivery > Flashcards

Veterinary drug delivery Flashcards

1
Q

why is veterinary drug delivery relevant to NZ?

A
  • NZ is home to 30.8million sheep

- NZ’s dairy cattle population is more than 6.6 million (in 2013)

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2
Q

What are the differences in veterinary pharmaceutical drug development vs. drug development for humans?

A
  • The formulation design is the same quality.
  • contemporary pharmaceuticals are equal
  • the quality of veterinary pharmaceuticals are no less than humans
  • human safety is part of the development process
  • advanced veterinary pharmaceuticals can be species specific
  • companion animals are a growing market similar to paediatrics
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3
Q

What are the benefits with veterinary pharmaceutical innovation?

A
  • gastro retention of veterinary pharmaceuticals have been exploited for decades
  • long term delivery of drug provides decreased costs and improved efficiency for farmer.
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4
Q

What are the regulatory differences between veterinary pharmaceuticals and human pharmaceuticals?

A
  • phase 1 trials are considered rapid as the pre-clinical test animal is the target animal for the drug
  • In the USA, their centre for veterinary medicine is part of the FDA. In NZ, we have an NZ agricultural compounds veterinary medicines which is part of the NZ food safety authorities.
  • The NCE must address environmental conditions as human safety is important due to being part of the food chain.
  • special terms used in veterinary pharmaceuticals
  • manufactured to GMP standards
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5
Q

What are the special terms used in veterinary pharmacueticals?

A
  • there is a witholding time/period that must be met

- there is a maximum residue level of substances which must be followed

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6
Q

What are the MRLs?

A

-maximum residue levels are the upper legal levels of a concentratin for drug residues in a specific tissue for food, such as muscle or milk

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7
Q

What are MRLs also known as?

A
  • minimum levels
  • this refers to the MRLs for agricultural and veterinary chemicals in agricultrual produce, especially for produce entering the food chain
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8
Q

What is the witholding time/period?

A

-the WHT refers to the minimum period of time that must elapse between the last treatment of an animal with a veterinary medicine and the supply of products (in meat or milk) from those animals for food consumption

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9
Q

What does the WHT depend on?

A
  • drug/product dependent

- animal species/tissue dependent

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10
Q

What are the 5 major factors for the need of new drug delivery technology for animal health?

A
  1. enhance consumer convenience and compliance
  2. improve pharmacokinetics of drugs
  3. extend patent life of proprietary molecules
  4. provide product differentiation
  5. assure target animal and consumer safety.
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11
Q

What forms of veterinary pharmaceuticals are there?

A

-various devices such as tablets, capsules, gels, powders and liquids

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12
Q

What is different about veterinary injectable products?

A
  • admin is different than for human
  • it is the preferred admin route in veterinary practice
  • animal health industry has generated strong interest in long term drug delivery for both companion and farm animals
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13
Q

What long acting injectable products are there?

A

-the formulation principle is the same as for humans
-for controlled release: can be
dissolution controlled depot
adsorption type depot
partition controlled depot
esterification type depot
encapsulation type
in situ solidifying depots

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14
Q

What are two unique routes of delivery which are common for veterinary pharmaceuticals

A
  1. intraruminal (into the cow’s stomach)

2. intramammary (into the cow’s udder)

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15
Q

What are intraruminal boluses?

A

-drug delivery devices designed to provide long-term delivery of drug to the rumen compartments of ruminant animals

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16
Q

What are the results of intraruminal boluses?

A
  • long term deliver (>100 days)

- retained in the rumen by geometry or density

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17
Q

What is a rumen?

A
  • essentially one of the compartments in the stomach of grazing animals
  • their GIT reflects a diet high in fibre but low in fat and protein
  • they are known as ruminant animals
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18
Q

What is the main differences in the rumen?

A
  • the intestinal tract consists of the same structures as other animals.
  • however the stomach is large (240L in mature cattle)
  • the stomach is also complex (has 4 compartments)
19
Q

What are the different compartments of the stomach?

A
  1. reticulum (pH 6)
  2. Omasum (pH 4-5)
  3. Abomasum (pH 2-3)
  4. Rumen (pH 5-7)
20
Q

What is the function of the rumen?

A

-turn food stuffs into absorbable nutrients. using microbial fermentation via protozoa/bacteria.

21
Q

What are the conditions of the rumen?

A

pH 5-7
38-42 degrees C
long retention time

22
Q

What implications does the conditions of the rumen have?

A

-absorbable fatty acids and gases are formed

which means there will be differences in the absorption rate of drugs and the bioavailability.

23
Q

How are slow release intraruminal devices retained by geometry?

A
  • the shape of the intraruminal drug delivery device is a cylinder with polymeric wings attached
  • the wings are constrained to the side of the cylinder during administration using a water soluble tape.
  • when it meets water, the wings expand and prevent regurgitaton following administration and subsequent dissolution of the tape.
24
Q

What are the main features of the geometry-retained intraruminal device for controlled drug release?

A
  • polymeric wings attached on a cylinder which open in an aqueous medium
  • Water proof cylinder with an orfice in one end and a spring in another end
  • A spring which acts as a piston which travels longitudinally within the tube to push the formulation to the orfice
  • drug is released from the orfice (so size of orfice is important)
  • core of matrix/tabelts which is an erodible composition containing the drug or nutrients. This comes in contact with the exterior environment via the orfice
25
Q

How does matrix erosion of the geometry retained intraruminal drug delivery device occur?

A

-water in through the orfice causes matrix erosion

26
Q

in the geometry retained intra-ruminal drug delivery device, what does the matrix form once in contact with water?

A
  • it forms a gel at the orfice

- needs to form a gel to push out through the orfice

27
Q

How is pulse drug release achieved using the geometry retained intra-ruminal drug delivery device?

A

-A spacer (containin no drug) can be used to create pulse drug release

28
Q

How is the drug/nutrient release controlled in the geometry retained intra-ruminal drug delivery device?

A

-Via erosion of the matrix

29
Q

What changes can we make to the geometry retained intra-ruminal drug delivery device to achieve controlled release?

A
  • properties of erodible composition of core tablets
  • drug concentration in the tablet matrix
  • size of orfice
  • manufacturing process
30
Q

What is the effect of changing the property of the erodible composition of the core tablets?

A
  • we can change viscosity of the core tablets. Higher viscosity = slower release
  • we can change the ratio of polymers to the other soluble excipients. Higher polymer:soluble excipient ratio = slower release
31
Q

How can drug concentration in the tablet matrix achieve controlled release?

A

increasing the drug concentration in the tablet matrix can increase the time the drug is released. (?)

32
Q

How can changing the orfice size achieve controlled release?

A

-orfice can be varied in size and thickness which controls the exposure area of the tablets to the rumen fluid

33
Q

How can manufacturing processes achieve controlled release?

A
  • tablets can undergo direct compression or granulation.

- the amount of force applied in compression will affect the release rate

34
Q

how are the intraruminal boluses administered into the cows?

A

-via a bolus gun

35
Q

What is Mastitis?

A
  • defined as inflammation of the milk secreting tissues of the udder
  • signs are characteristic of an inflammatory response: pain, swelling, heat, redness
  • results in loss of function producing abnormal milk
36
Q

What is the implication of mastitis in cows?

A
  • expected ~35billion USD annual loss

- annual antibiotic cost appears to be $17.7 million in NZ

37
Q

What causes mastitis?

A

-the udder becomes inflammaed in response to invasion of bacteria, usually through the teat canal.

38
Q

What is the purpose of the keratin plug in the bovine teat?

A
  • it is a naturally occuring defence mechanism against mastitis.
  • It prevents bacteria from moving up the teat canal
39
Q

How are intramammary products classified?

A
  1. dry cow products
  2. lactating/milking cow products

they are typically 2-5mL, highly viscous, oil based antimicrobial infusions which are sterile.

40
Q

What are the characteristics of MC (milking cow) products

A

-antimicrobial infusions which are
-low viscosity (but still more viscous than injections)
because cow is in milking phase so want the drug to treat and go back to milking as soon as possible after the WHT
-often water soluble form of antibiotics (such as Na or K salts)

41
Q

What are the characteristics of DC (dry cow) products?

A
  • prolonged release as the cow is in its resting period and won’t be milked.
  • high viscosity
  • thickened by addition of wax to oil
  • water insoluble antibiotics (achieved by esterification)
  • higher dose of antibiotic than MC products
  • longer retention time in the udder (~2 months)
42
Q

What are teat sealants?

A
  • these are products which seal the teat canal to stop bacteria colonisation and prevent mastitis
  • can be internal (infusion) or external (topical spray)
43
Q

What is an example of an internal teat sealant?

A

-Teatseal is an inert substance containing 65% bismuth subnitrate in a paraffin base. It is a highly viscous and high density gel which is given by infusion to prevent mastitis.

44
Q

What is an example of an external teat sealant?

A
  • applied by topical spray
  • forms a protection film around the udder when cow is in dry phase
  • adherence is a challenge as resprays needed.

Pharm304 (21 decks)

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