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203 - Theme 1 - The Endocrine System > L20 - Hormonal drug delivery > Flashcards

L20 - Hormonal drug delivery Flashcards

1
Q

Example of dosage forms

A

IV drip

Tablets

Injections

Patch

Inhalers

Topical treatments

Oral syrups

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2
Q

Why do we have dosage forms?

A

Drug often in powder form

Tiny doses of drug
-mg or msg quantities

Bulk up with exipients
-such as water, lactose

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3
Q

Why do we have different dosage forms?

A

Different clinical conditions

Different types of patient

Different routes of administration

Different physicochemical properties of drug

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4
Q

Factors to consider when designing dosage forms

A

Drug factors
-solubility, partition coefficient, pKa, stability, MWt

Biopharmaceutical factors
-absorption, bioavailability, route of administration

Therapeutic factors
-disease, patient, route, local vs. systemic delivery

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5
Q

Types of hormones

A

Modified amino acid derivatives
-derived from tyrosine and tryptophan e.g. dopamine, thyroxine

Peptide and proteins
-derived from amino acids e.g. neuropeptides (vasopressin), pituitary hormones (gonadotrophins), GI hormones (insulin)

Steroids
-derived from cholesterol e.g. sex hormones (testosterone), corticosteroids (hydrocortisone)

Eicosanoids
-derived from lipids e.g. prostaglandins, leukotrienes

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6
Q

Systemic delivery: bioavailability of drugs

A

entry into blood is required

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7
Q

When might you not want systemic delivery?

A

Side effects e.g. corticosteroids

Bioavailability is low e.g. peptide hormones, sex hormones

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8
Q

Modified amino acid derivatives e.g. thyroxine and corticosteroids (hydrocortisone)

A

Drug factors
-low dose required

Biopharmaceutical factors
-orally bioavailable

Therapeutic factors
-local vs systemic delivery

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9
Q

Excipients when the dose of the drug is low

A
  • Diluents/fillers e.g. lactose, water
  • Surfactants e.g. polysorbates
  • Lubricants e.g. Mg stearate
  • Disintegrants e.g. starch
  • Viscosity enhancing agents e.g. cellulose derivatives
  • Flavours, colours, perfumes
  • Sweetening agents
  • Preservatives
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10
Q

Local delivery

A

Site of administration = site of action

Rapid onset of action

Less drug required

Absorption into the bloodstream is not required

Absorption into the bloodstream can lead to unwanted side effects

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11
Q

Local delivery of corticosteroids

A

To avoid systemic side effects need many different dosage forms

  • intra-articular injections - tennis elbow
  • creams and ointments - eczema
  • inhalers - asthma
  • eye drops - inflammation
  • suppositories - haemorrhoids
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12
Q

Peptide hormone e.g. insulin

A

Drug factors
-peptide hormone, large molecule MW approx 5800 Da

Biopharmaceutical factors
-not absorbed after oral administration

Therapeutic factors
-need systemic action
-aim to mimic insulin secretion by normal pancreas
=>basal and bolus

Not absorbed after oral administration because enzymatic degradation in lumen of GIT, any that survives can’t readily cross GI epithelium into blood because too large

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13
Q

Insulins characterised by differences in:

A

Onset
-how quickly they act

Peak
-how quickly they achieve maximum impact

Duration
-how long they last

Route of delivery
-subcutaneous, inhaled

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14
Q

Continuous subcutaneous insulin infusion (CSII) of rapid analog

A

Dosage instructions are entered into the pump’s small computer and the appropriate amount of insulin is then injected into the body in a calculated controlled manner

Provides the basal insulin replacement, as well as the mealtime and high blood sugar correction insulin replacement

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15
Q

Pulmonary route

A

Mainly for local delivery but

Systemic delivery:

Large SA
-80-140m^2

Thin epithelial barrier
-0.1-0.2um

Good blood supply
-100% cardiac output

Avoids harsh environment of GI tract

Avoids first-pass hepatic metabolism

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16
Q

Inhaled insulin - Afrezza (June 2014 FDA)

A

Rapid-acting inhaled insulin

Taken at the beginning of each meal

Used in combination with a long-acting injected insulin

17
Q

Sex hormones

A

Drug factors
-steroid, lipophilic, MW approx 270 Da

Biopharmaceutical factors

  • variable absorption after oral administration
  • extensive first pass hepatic metabolism, short t1/2

Therapeutic factors

  • systemic delivery required but try to avoid oral route
  • ethical cyclical or continuous administration required
18
Q

Why do you need alternatives to oral route?

A

To increase bioavailability

To offer sustained release

19
Q

Types of routes in systemic delivery

A

Parental route - IM injection, implant

Transdermal route - patch or gel

Intranasal route - spray

Buccal route - mucoadhesive system

Vaginal - gel

20
Q

IM injection

A

Oily injections - sustained release

  • testosterone enantate (caster oil)
  • testosterone decanoate, isocaprate, phenylproprionate and proprionate, proprionate, undecanoate

Implants - sustained release
-nexplanon (progestogen-only contraception)

21
Q

Ester at position 17

A

Decreases water solubility

Increases oil solubility

Deactivates molecule
-can’t bind to androgen receptor

Ester cleaved/hydrolysed in blood
-restores -OH so can attach to receptor

22
Q

Release of steroid molecules

A

from oily deposits of long-chain esters in muscle tissue

Oil has some affinity for water and thus allows penetration of water; the ester is hydrolysed at the surface of the droplet.

The total surface area of the droplet can influence release rate and hence pharmokinetics of the drug.

Droplet dimenions and total surface area influenced by:
force of injection
viscosity and surface tension of oil phase
size of needle
environment into which it’s injected – exercise can increase plasma levels by increasing surface area of droplet

23
Q

Subnormal implant of etonogestrel (Nexplanon)

A

Nexplanon - progestogen only contraception

Contains etonogestreln 68mg in each flexible rod

Delivered by sub dermal implantation

Provides effective contraception for up to 3 years unless BMI greater than 35 in which case may not provide effective contraception in 3rd year

24
Q

Transdermal delivery of estradiol - systemic

A

Patch design and technology

  • there are 2 major types of transdermal delivery system (TDS) products:
    1) Reservoir
    2) Matrix
25
Q

Intranasal administration - systemic: Advantages

A

Large surface area (approx 180 cm^2)

Highly vascularised

Avoids first pass hepatic metabolism

Good bioavailability for low MW compounds

26
Q

Intranasal administration - systemic: Disadvantages

A

Mucocilliary clearance

Metabolic activity

Poor bioavailability for high MW compounds

27
Q

Product on the market Intranasal administration

A

Desmpressin

28
Q

Buccal administration - systemic

A

Mucoadhesive testosterone buccal delivery system

Applied twice daily

Adheres to gum or inner cheek

Sustained release of testosterone through buccal mucosa

29
Q

Vaginal administration - systemic

A

Self-insertion and removal

Continuous release

Good patient compliance

Bioadhesive gel (Crinone)
-progesterone released over 25-50h
30
Q

Vaginal administration (local) - device

A 
Vaginal ring (Estring)
-estradiol released over 90 days

Treatment of urogenital symptoms associated with postmenopausal atrophy of the vagina

31
Q

Vaginal administration (local) - pessary

A

Estradiol 10mcg vaginal tablets (inserts) (Vagifem)

32
Q

Intra-uterine progestogen-only device

A 
Intrauterine system (IUS) (Mirena, Jaydess, Levosert)
-levonorgestrel (52mg) released into uterine cavity over 3 or 5 years - local action
33
Q

Mirena

A

Progestasert (Mirena) provides local rather than systemic contraception.

May inhibit sperm survival and/or alter uterine environment to prevent nidation.

Advantages:
Uses natural hormone at much lower dose than by other routes.
Don’t need to take/admin daily
No estrogens
T-shaped device for comfort, safety and retention – minimal mechanically –induce irritation
Hormonal action confined to uterus

34
Q

Eicosanoid hormones

A

Prostaglandins E2 (Prostin E2, dinoprostone)

Vaginal gel

Vaginal pessary/tablet (Propess)

PGE2 released over 12 hours, local action to ripen cervix

203 - Theme 1 - The Endocrine System (11 decks)

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