NEET MDS Lessons
Pharmacology
PHARYNGEAL DEMULCENTS
Administered in the form of lozenges, cough drops and cough linctus.
Produce soothing action on throat directly and by increasing the flow of saliva and provide symptomatic relief from dry cough.
EXPECTORANT
Expectorants are the drugs which increase the production of bronchial secretion and reduce its viscosity to facilitate its removal by coughing.
ANTITUSSIVES
They are central cough suppressants and act centrally to raise the threshold of cough centre and inhibit the cough reflex by suppressing the coordinating cough centre in the medulla oblongata.
Codeine - it depresses cough centre but is less constipating and abuse liability is low.
Pholcodeine is similar to codeine in efficacy and is longer acting. It has no analgesic or addicting property.
Noscapine is another opium alkaloid of benzylisoquinoline group. It is used as antitussive with no analgesic and drug abuse or drug dependence property.
Dextromethorphan is a synthetic compound and its dextroisomer is used as antitussive and is as effective as codeine
Pipazethate is another synthetic compound of phenothiazine category used as antitussive with little analgesic and sedative properties.
ANTIHISTAMINICS
They do not act on cough centre but provide relief due to their sedative and anticholinergic action.
BRONCHODILATORS
Bronchodilators are helpful in individuals with cough and bronchoconstriction due to bronchial hyperreactivity. They help by improving the effectiveness of cough in clearing secretions.
TRIMETHOPRIM
It is a diaminopyrimidine. It inhibits bacterial dihydrofolate reductase( DHFRase).
In combination with sulphamethoxzole it is called Co-trimoxazole.
Spectrum of action
S. Typhi. Serratia. Klebsiela and many sulphonamide resistant strains of Staph.aureus. Strep pyogens
Adverse effects
Megaloblastic anemia. i.e.. due to folate defeciency.
Contraindicated in pregnancy.
Diuretics if given with co-trimoxazole cause thrombocytopenia.
Uses
I. UTI. 2. RTI. 3. Typhoid. 5. Septicemias. 5. Whooping cough
Characteristics of Opioid Receptors
mu1
Agonists : morphine phenylpiperidines
Actions: analgesia bradycardia sedation
mu2
Agonists : morphine phenylpiperidines
Actions: respiratory depression euphoria physical dependence
delta
Actions: analgesia-weak, respiratory depression
kappa
Agonists: ketocyclazocine dynorphin nalbuphine butorphanol
Actions: analgesia-weak respiratory depression sedation
Sigma
Agonists: pentazocine
Action: dysphoria -delerium hallucinations tachycardia hypertension
epsilon:
Agonists: endorphin
Actions: stress response acupuncture
Uses of NSAIDs
NSAIDs are usually indicated for the treatment of acute or chronic conditions where pain and inflammation are present. Research continues into their potential for prevention of colorectal cancer, and treatment of other conditions, such as cancer and cardiovascular disease.
NSAIDs are generally indicated for the symptomatic relief of the following conditions.
rheumatoid arthritis, osteoarthritis, inflammatory arthropathies (e.g. ankylosing spondylitis, psoriatic arthritis, Reiter's syndrome), acute gout, dysmenorrhoea, metastatic bone pain ,headache and migraine, postoperative pain, mild-to-moderate pain due to inflammation and tissue injury, pyrexia, renal colic
Aspirin, the only NSAID able to irreversibly inhibit COX-1, is also indicated for inhibition of platelet aggregation; an indication useful in the management of arterial thrombosis and prevention of adverse cardiovascular events.
Nalidixic acid:
Nalidixic acid is the basis for quinolone antibiotics. It acts bacteriostatically (that is, it inhibits growth and reproduction) or bactericidally (it kills them) on both Gram positive and Gram negative bacteria, depending on the concentration. It is especially used in treating urinary tract infections, caused for example by Escherichia coli, Proteus, Enterobacter and Klebsiella.
Antifungal
There are several classes of antifungal drugs.
The polyenes bind with sterols in the fungal cell wall, principally ergosterol. This causes the cell's contents to leak out and the cell dies. Human (and other animal) cells contain cholesterol rather than ergosterol so are much less suceptible.
Nystatin
Amphotericin B
Natamycin
The imidazole and triazole groups of antifungal drugs inhibit the enzyme cytochrome P450 14α-demethylase. This enzyme converts lanosterol to ergosterol, and is required in fungal cell wall synthesis. These drugs also block steroid synthesis in humans.
Imidazoles:
Miconazole
Ketoconazole
Clotrimazole
The triazoles are newer, and are less toxic and more effective:
Fluconazole
Itraconazole
Allylamines inhibit the enzyme squalene epoxidase, another enzyme required for ergosterol synthesis:
Terbinafine
Echinocandins inhibit the synthesis of glucan in the cell wall, probably via the enzyme 1,3-β glucan synthase:
Caspofungin
Micafungin
Others:
Flucytosine is an antimetabolite.
Griseofulvin binds to polymerized microtubules and inhibits fungal mitosis.
Codeine
Codeine is methyl morphine, with a methyl substitution on the phenolic hydroxyl group of morphine. It is more lipophilic than morphine and thus crosses the blood–brain barrier faster.
- classified as a simple, or mild analgesic, codeine is often used in low doses as an oral analgesic has a much better oral/parenteral absorption ratio than morphine.
- Effective for mild to moderate pain.
- Constipation occurs
- Dizziness may occur in ambulatory patients.
- More potent histamine-releasing action than does morphine.
- Should not be administered by IV injection.
- Extremely effective antitussive agent and is used therapeutically for suppressing cough.
- In contrast to morphine, codeine overdose can occasionally lead to the production of seizures.
- Seizures can be treated with barbiturates.
- Respiratory depression can be counteracted with Naloxone.
- orally, 30 mg of codeine is equi-analgesic to 600 mg of aspirin, however, the effects of the two are additive, and occasionally synergistic