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Describe the mechanism of action of opioids.
Released by interneurons to stimulate opioid receptors to enhance inhibitory effects and mediate analgesia. This “closes the gate” to inhibit afferent transmission and enhance natural pain relief responses.
Describe morphine’s use.
A standard analgesic used for severe pain, acute and chronic pain. It comes in an oral solution, regular and EC tablets, IM/SC/IV/IT injections and epidurals.
Describe codeine’s use.
A weak opioid metabolised to morphine, for mild to moderate pain and cough suppression.
Describe fentanyl’s use.
A highly potent drug for moderate to severe pain, anaesthesia, chronic and breakthrough pain. It comes in a SL tablet, SC/IV/IT injection, epidural, transdermal patch and lozenge, and is dosed in micrograms.
Describe hydromorphone’s use.
A rapid-onset but less sedative drug that comes in an oral solution, regular or EC tablets and IM/IV/SC injections.
Describe methadone’s use.
A drug for severe postoperative or chronic pain. It comes in an oral syrup, tablet and IM/IV/SC injections. It has a long half-life (accumulation risk) so monitor for signs of dependence.
Describe oxycodone’s use.
An opioid with a variable oral bioavailability (50-90%). It comes in an oral liquid, regular or EC tablets and SC/slow IV injections.
Describe the mechanism of action of naloxone.
A short-acting opioid antagonist used for overdoses and reversal of opioid depressant effects, given parenterally to displace opioids from receptor sites. The half like is 0.5-1 hour (may need frequent doses).
Describe non-steroidal anti-inflammatory drugs (NSAIDS).
For mild/moderate pain, inhibits prostaglandin formation (inflammatory mediator, causes pain). Opioid-sparing effects, reduces opioid dosage when combined (eg. indomethacin, aspirin or ibuprofen). Can cause gastric pain, ulcers, GI bleeds, fluid retention, electrolyte imbalances and hypertension.
Describe paracetamol.
For mild/moderate pain, fever, migraines, and osteoarthritis. Can be used with opioids for chronic pain to reduce the number of opioids, delaying tolerance and dependence. 20+ tablets (10g) can cause hepatotoxicity.
Describe amitriptyline’s use.
A tricyclic antidepressant (adjuvant medication for neuropathic pain).
Describe gabapentin and pregabalin’s use.
An anticonvulsant (adjuvant medication for neuropathic pain).
Describe general anaesthesia.
Unconscious, amnesia, muscle relaxant, reflex depression effects achieved with multiple drugs to produce a safer induction, quicker recovery and lower post-op complications.
Describe the 4 aspects of general anaesthesia.
Premedication (midazolam for anti anxiety, atropine to stop secretions)
Drugs producing reversible unconsciousness, analgesia, muscle relaxant effects, amnesia (propofol) for induction and maintenance of GA
Maintenance anaesthetic by inhalation (nitrous oxide)
Antiemetics and opioids for post-op nausea/pain
Describe local anaesthetics.
Topical or local infiltrates, regional blocks, cocaine-based (eg. lidocaine or prilocaine), used for minor procedures and when consciousness is required.
Describe awake anaesthesia.
Just involves sedation and analgesia, not complete unconsciousness.
Describe central nerve blocks.
For lower abdomen/extremity procedures, elderly patients or those with severe respiratory problems, liver/kidney/metabolic diseases where GA is contraindicated. Causes headache, paraesthesia, hypotension, low cardiac output. Spinal anaesthesia goes into CSF, epidurals go into the spinal cord.
Describe chemotherapy.
Non-selective cytotoxic drugs targeting cellular/metabolic processes vital to malignant and normal cell growth/division, for curative and palliative intent.
Describe adjuvant and neo-adjuvant chemotherapy.
Adjuvant chemo: Use after tumour removal/treatment (eg. surgery) to prevent growth of residual metastasis deposits, used in earlier-detected stages.
Neo-adjuvant chemo: Use before local control surgery/irradiation to decrease initial tumour size, less invasive local treatment, used in more advanced stages.
Explain how chemotherapy is strategically administered.
It is given in chemo cycles which is effective against rapidly-dividing cells, non-selective, more adverse effects (all cells equally destroyed), given with a break between cycles so healthy cells recover before cancer cells do. A combination of chemo agents may also be used to target a different cell cycle phase to maximise the number of cancer cells destroyed, decreases drug resistance.
Describe hormone therapy.
Some tumours depend on body hormones. Stop hormone production to achieve cancer death (eg. tamoxifen for cancers of the reproductive organs).
Describe immunotherapy.
A biological treatment, manipulates immune system to help it fight more effectively. Meds tag cancer cells so immune cells can easily find/destroy them.
Describe monoclonal antibodies and adoptive cell transfers.
Monoclonal antibodies: Drugs with antibodies bind to certain antigens on cancer cells, leads to their destruction (eg. rituximab binds to B lymphocytes on B cells).
Adoptive cell transfer: Boosts natural T cell’s ability to kill cancer (CAR T-cell therapy).
Describe radiotherapy.
Ionising radiation damages DNA/microenvironment. Given through external radiation or internally (implants - brachytherapy). There are significant adverse effects to surrounding areas, new cells are more radiosensitive (pancytopenia can occur in the pelvic region, large bone marrow area).
Describe the use of surgery in cancer treatment.
For benign or premalignant tumours pressing on organs, nerves, skin, mouth or cervix. In early stages, its removed with a good margin of normal tissue. In advanced (debulking) stages, most is removed, high adjuvant chemo success. Palliative surgery relieves/prevents/delays symptoms.
What are some adverse effects of cancer treatments in the GI tract, bone marrow and hair?
GI tract ulcers, malabsorption, mucositis, diarrhoea, disruption of barrier defences. Chemo targets rapidly dividing cells including bone marrow/hair, radiation suppresses function/growth.
What are some adverse effects of cancer treatment in the reproductive tract, skin and nausea?
Chemo affects gametes/fertility, decreased skin renewal rates, dryness, breakdown, infection, erythemas, nausea is caused by chemo acting on CNS vomiting center, antiemetic therapy needed.
What medication is used in tumour lysis syndrome?
Allopurinol, a therapeutic alkalinising agent is used to treat or prevent tumour lysis syndrome.
What is given in patients presenting with febrile neutropenia?
Broad spectrum antibiotics within 30 minutes of presentation.
How is pernicious anaemia treated?
Cyanocobalamin (Vit B12 replacement) via weekly injection until the deficiency is corrected, then monthly lifelong injections. It requires intrinsic factor (secreted in the stomach) to be absorbed into the body.
Describe folate’s importance.
Essential vitamin for DNA production with developing erythrocytes, intake only occurs through diet.
Describe the importance of ferrous sulphate.
It is used to treat iron deficiency anaemia which is caused by low blood haemoglobin levels.
Describe heparin-induced thrombocytopenia.
An immune-mediated adverse reaction, IgG antibodies bind to platelet receptors, activates aggregation, causes low free platelet numbers and rapid thrombosis development. Use other anticoagulants and reverse with protamine sulphate.
Describe the treatment of Non-Hodgkin’s Lymphoma.
Chemotherapy, corticosteroids, radiation therapy, stem cell transplants, rituximab (monoclonal antibody against antigen CD20 on B cell surfaces + chemo).
Describe “novel agents” in treating multiple myeloma.
They aim to destroy myeloma cells in bone marrow (eg. lenalidomide, thalidomide, bortezomib).
Describe the mechanism of action of antihistamines.
They block histamine receptors to alleviate allergy symptoms.
Describe the mechanism of action of adrenaline.
An adrenergic agonist that causes bronchodilation and vasoconstriction.
Describe filgrastim’s use.
A recombinant colony-stimulating factor that is used to treat neutropenia. Recombinant clotting factors are plasma clotting factor concentrates made in labs rather than natural blood products, used to treat haemophilia.
Describe prednisone’s use.
It suppresses leucocyte migration and reverses increased capillary permeability, suppressing the immune system by reducing its activity and volume. Can block insulin’s action to cause hyperglycaemia (induce resistance, trigger glucose production via the liver). Overall, it’s a corticosteroid for anti-inflammatory and immunosuppressive effects.
What is the treatment for Myasthenia Gravis?
Anti-cholinesterase drugs to enhance neuromuscular transmission. This allows more acetylcholine to be present for muscle contraction synapses.
What is the treatment for rheumatoid arthritis?
Anti inflammatory drugs and anti-rheumatic drugs like methotrexate (immune suppressant).
What is the treatment for multiple sclerosis?
Corticosteroids for their anti-inflammatory properties, and immune modulating drugs like interferons and glatiramer, suppressing T cells.
What is the treatment for Chron’s Disease?
Treat with steroids, supplements, immunosuppressants and monoclonal antibodies, aiming for long term remission.
Describe corticosteroids.
Anti-inflammatory agents like dexamethasone or hydrocortisone that can increase BGL and cause agitation, insomnia, weight gain and poor wound healing.
Describe antiretroviral drugs.
For HIV, therapy helps stop damage to allow the immune system to self-repair. Highly active antiretroviral therapy (HAART) is the current regimen, involving a combo of 3+ antiretrovirals. Combo drugs include inhibitors of viral enzymes used in different stages of replication in CD4+ Helper T cells.
What is the management for cardiogenic shock?
Adrenaline, anti-platelet therapy, pain relief, O2 therapy and very careful fluid therapy.
What is the treatment for anaphylactic shock?
Remove the antigen, IM adrenaline, IV fluids to reverse hypovolaemia, antihistamines, and corticosteroids to stop inflammation.
Describe the mechanism of action of penicillins.
It inhibits bacterial cell wall synthesis by weakening the cell wall, causing lysis and death (most effective, least toxic, likely combined with tazobactam). They are narrow (benzylpenicillin), moderate (amoxicillin) or broad spectrum (piperacillin with tazobactam). Patients allergic to penicillin can also be allergic to carbapenems or cephalosporins.
Describe the mechanism of action of carbapenems.
It inhibits bacterial cell wall synthesis, broad spectrum class of medication. Adjust the dose in patients with renal impairments (eg. meropenem treats meningitis).
Describe the mechanism of action of cephalosporins.
It inhibits bacterial wall synthesis (not 1st line), can be given to patients with penicillin allergies with caution, not if they have anaphylaxis (cefepime 4th gen). Has a bleeding risk (watch INR, caution with haematological conditions) and high sodium contents (caution on sodium-restricted individuals).
Describe the mechanism of action of vancomycin.
It inhibits bacterial cell wall synthesis, active against MRSA and CDIFF. There’s a risk of resistance (VRE). Treats serious infectious where there is resistance/allergies to other antibiotics. Watch out for nephrotoxicity and ototoxicity, pain, and thrombophlebitis (irritates tissue, use a large cannula).
Describe the mechanism of action of amnioglycosides.
It inhibits protein synthesis, potent, for serious life threatening infections (eg. gentamicin). Use with penicillins, cephalosporins or vancomycin for their synergistic effects. Watch plasma concentration and renal function.
Describe the mechanism of action of macrolide antibiotics.
Inhibits protein synthesis (eg. azithromycin), for when other antibiotics are contraindicated from allergies. Clarithromycin is used with amoxicillin and omeprazole (PPI) to treat H. pylori.
Describe the mechanism of action of fluoroquinolones.
Inhibits DNA replication/repair (eg. ciprofloxacin) for when other drugs are ineffective or contraindicated. Resistance to this drug is increasing over time.
Describe the mechanism of action of metronidazole.
It inhibits bacterial protein synthesis (broad spectrum). Avoid alcohol at least 3 days after administration, can have dark urine as a side effect.
Describe the mechanism of action of urinary tract antimicrobials.
Drug therapy starts before cultures come back (eg. cefalexin, ciprofloxacin).
Describe lipase inhibitors.
They inhibit nutrient absorption (anti-obesity drug, eg. Orlistat).
Describe sympathomimetic anorectics and give an example.
They mimic or stimulate the adrenergic nervous system, for short term use, can raise BP (anti-obesity, eg. Phentermine).
What are atropine and hyoscine used for?
They are muscarinic receptor antagonists (or anticholinergic drugs) that block ACh at muscarinic receptors to block the effects of the parasympathetic nervous system stimulation (treats Parkinson’s Disease).
Describe the mechanism of action of Botulinum toxin (Botox).
It destroys ACh muscle receptors to cause fatigue and muscle weakness.
Describe the action of anticholinesterase drugs.
They raise ACh levels in cholinergic pathways to enhance brain function/slow decline. It inhibits the acetylcholinesterase enzyme to allow for ACh accumulation (enhanced effect at neuromuscular junctions to produce adverse effects associated with ACh increases, eg. donepezil, galantamine, rivastigmine). May delay deterioration by 6-18 months, not for mild deficits.
Describe the mechanism of action of Memantine.
An antagonist at a type of glutamate receptor (excitatory neurotransmitter causing degradation). It reduces neuronal degradation from excess glutamate in moderate/severe dementia, combined with anticholinesterase drugs. Adverse effects like hallucinations and fatigue are common.
What are some other drugs for symptom management of dementias?
Antipsychotics like olanzapine/quetiapine, benzodiazepines like diazepam or lorazepam, and anti-depressants like mirtazapine or citalopram.
Describe the action of riluzole.
It delays disease progression and prolongs survival (neuro-protective). It is a glutamate antagonists which inhibits overfiring of nerve impulses, used for motor neuron disease.
Describe the drugs used to treat cerebral palsy.
Baclofen (muscle relaxant, activates GABA receptors) and Botulinum toxin (Botox, blocks the release of ACh causing generalised muscle weakness).
Describe the mechanism of action of levodopa and carbidopa.
Levodopa increases dopamine. Dopamine doesn’t cross the BBB but levodopa is a pre-cursor, so it crosses the BBB then converts to dopamine to increase levels of dopamine in the brain. It’s given with carbidopa to limit peripheral interconversion of levodopa outside the brain (ensures conversion happens in the brain where it is most effective).
When is levodopa-carbidopa given to patients?
For treatment of Parkinson’s Disease. Only given with debilitating symptoms (advanced Parkinson’s is unresponsive to it). There are many side effects like mental changes, nausea, dyskinesia (involuntary movements) and the drug becomes less effective over time.
Describe the 3 types of medications given for seizure treatment.
Stabilises nerve cell membranes by altering cation transport (Na+, K+, Ca+, eg. sodium valproate, phenytoin or carbamazepine).
Enhances gamma-aminobutyric acid (GABA) effects (eg. benzodiazepines like midazolam or clonazepam).
Modulates the release of glutamate (levetiracetam).
What are some pharmacological strategies for osteoporosis?
Vitamin D and oral calcium supplements, biphosphonates to inhibit osteoclasts (zoledronic acid), monoclonal antibodies to inhibit osteoclasts (denosumab), raloxifene (postmenopausal osteoporosis), teriparatide (recombinant PTH, low dose, stimulates osteoblast maturation).
Describe gonadotropin releasing hormone (GnRH) as a drug/hormone in low and high doses.
At low doses, FSH and LH are released to regulate female reproductive systems. Continuous administration in high doses causes de-sensitisation and low pituitary production of FSH and LH (stops growth of steroidal-dependent tumours).
Give examples of gonadotropin-releasing hormone (GnRH) as a drug in low and high doses.
In low doses, the synthetic form of GnRH is used to induce ovulation (eg. Gonadorelin). In high doses, the drug reduces androgen production in the testes (eg. Degarelix).
What is the treatment for premenstrual syndrome?
Selective serotonin re-uptake inhibitors (SSRIs) like sertraline or fluoxetine treat premenstrual dysphoric disorder. Anti prostaglandins and GnRH agonists are also used to suppress ovulation, and are a second line treatment for severe cases of PMS.
Describe the treatment for endometriosis.
NSAIDs, combo oral contraceptives, medroxy-progesterone (continuous dose, stops uterus overgrowth). GnRH agonists suppress ovulation, and a laparoscopic ablation (tissue removal) treats pain and infertility.
Describe the treatment for polycystic ovary syndrome.
Anti-androgen agents, combination oral contraceptives, hypoglycaemic agents, weight reduction and exercise regimes.
Describe the treatment for benign prostatic hyperplasia.
Dutasteride, finasteride (stops testosterone, reduces gland hypertrophy), prazosin, terazosin (relaxes smooth muscle, relieves urinary obstruction by blocking alpha 1 receptors).
