Block 11 Pharmacology

Question 1

Folic acid (Vitamin B9)

Answer 1

DNA precursor

Uses: treatment and prevention of folate deficiencies and megaloblastic anaemia. Prevents neural tube defects in growing foetus

MOA: Converted to tetrahydrofolic acid/ methyltetrahydrofolate by dihydrofolate reductase (DHFR) -> needed for EPO synthesis and purine/pyrimidine synthesis

Question 2

Desogestrel/Etonogestrel / Levonorgestrel

Answer 2

Synthetic progesterone

Uses: Oral contraceptive pill or treatment of endometriosis

MOA: Progesterone Nuclear Receptor Agonist -> slows GnRH release from hypoT reducing the pre-ovulatory LH surge and maintains high levels of progesterone -> SUPPRESSES OVU
LATION

Note: in high doses levonogestrel can be used as emergency contraception

note: Can also be given in a combined pill (progesterone and oestrogen)

Question 3

Oxytocin

Answer 3

Synthetic hormone/ GPC oxytocin receptor agonist

Uses: Induces labour (stimulate contraction of uterine smooth muscle, used in delivery and immediately postpartum)

MOA: Activates uterine receptors to increase intracellular calcium, activate myosin’s light chain kinase, and therefore cause muscle contraction.

note: Oxytocin after labour often associated with lactation

Question 4

Ethinylestradiol/Oestradiol

Answer 4

Ostradiol: type of naturally occurring ostrogen hormone

Enthiylestradiol: A synthetic form of oestradiol

Uses: contraceptive pill

MOA: Bind oestrogen receptor causing translocation to nucleus and regulation of gene transcription -> increases synthesis of sex hormone binding globulin (SHBG), thyroid-binding globulin (TBG), suppresses follicle-stimulating hormone (FSH) -> prevents ovulation

Question 5

Dinoprostone

Answer 5

Prostaglandin E2 -> Prostaglandin receptor agonist

Uses: Given as a vaginal suppository to soften the cervix in labour and induce labour,

MOA: stimulates the myometrium of the uterus to contract (exact mechanism unknown)

Question 6

Flucloxacillin

Answer 6

Beta-lactam antibiotic (transpeptidase inhibitor)

Uses: Usually Gram + bacteria but also Gram - bacteria. Also stable against bacteria producing beta lactamase

MOA: Bactericidal. Inhibits bacterial cell wall synthesis by binding to specific penicillin-binding proteins (PBPs) located inside the cell wall. Cell lysis occurs via autolytic enzymes such as autolysins

Note: Commonly used in place of methicillin

Question 7

Tetracycline

Answer 7

A 30s inhibitor (antibiotic)

• A broad-spectrum antibiotic
• Used to treat many infections, including acne.

Uses: infections caused by a variety of Gram positive and Gram negative microorganisms including Mycoplasma pneumoniae, Pasteurella pestis, Escherichia coli, Haemophilus influenzae (respiratory infections), and Diplococcus pneumoniae.

• MOA inhibition of bacterial cell growth by binding to the 30S ribosomal subunit.
• Prevents tRNA from binding ribosome site
• Inhibition of translation

note: Rarely used, replaced by doxycycline

Question 8

Ampicillin

Answer 8

Beta-lactam antibiotic (transpeptidase inhibitor)

Uses: Gram positive bacterial infections

MOA: Inhibits bacterial cell wall synthesis by binding to specific penicillin-binding proteins (PBPs) located inside the cell wall. Cell lysis occurs via autolytic enzymes such as autolysins

note: replaced by amoxicillin now

Question 9

Sodium valproate

Answer 9

Anti-convulsant (GABA receptor agonist)

Uses: Anti-epileptic (control absence seizures, tonic-clonic seizures grand mal and complex partial seizures) and mood stabiliser (in mania)

MOA largely unknown: Increased brain conc of GABA, also block reuptake of GABA. may inhibit enzymes that catabolise GABA

Question 10

Ethanol

Answer 10

A neuronal depressant

Uses: Recreational use, Not really used therapeutically

MOA:

• binds NT receptors for Ach, serotonin, GABA and glutamate
• sedative effect via GABA and glycine receptor binding
• dehydrating agent -> disrupts osmotic balance

Question 11

Cocaine

Answer 11

Noradrenaline reuptake inhibitor/ sodium channel blocker - Local anaesthetic

Uses: Recreational, Local/topical anaesthesia of mucous membranes (oral, laryngeal, nasal), though little clinical use now.

MOA:

• Reversibly binding/inactivating sodium channels, preventing depolarisation of nerve cell membranes and therefore blocking the propagation of impulses along the nerve
• Vasoconstrictive properties via inhibition of NA reuptake
• Addictive properties due to inhibition of dopamine reuptake

Question 12

Lithium

Answer 12

A mood stabilising agent (Sodium analogue)

Uses: Treatment of bipolar disorder (counteracts mania and depression)

MOA unknown: Lithium ion Li+, has a smaller diameter so can easily displace K+, Na+ and even Ca+2 occupying their sites in several critical neuronal enzymes and neurotransmitter receptors

Question 13

Thalidomide

Answer 13

Immunomodulatory agent (immunosuppressive and anti-angiogenic)

Uses: Cancer and leprosy

MOA: suppression of TNF-a reducing inflammation. Also VEGF inhibitor so decreased angiogenesis important to inhibit in cancer

Question 14

Testosterone

Answer 14

Steroid sex hormone (androgen receptor agonist)

Uses: in males with too low testosterone levels, breast cancer
-Function in men: stimulate spermatogenesis, maturation of spermatozoa, support development of secondary sexual characteristics, stimulate overall growth and influence brain development by stimulating sexual behaviours

MOA: Reduced to 5-DHT or activates androgen receptors -> influences gene transcription

Question 15

Somatropin

Answer 15

Synthetic human growth hormone -> hGH receptor agonist

Uses: To treat dwarfism and growth failure

MOA: Binds human growth hormone -> causes dimerisation and activation of JAK2 pathway signalling -> increase in growth and change in metabolism