NEET MDS Lessons
Pharmacology
Ketoconazole
synthetic antifungal drug
used for infections such as athlete's foot, ringworm, candidiasis (yeast infection or thrush), jock itch.
Ketoconazole is used to treat eumycetoma, the fungal form of mycetoma.
MOA: Ketoconazole is imidazole structured, and interferes with the fungal synthesis of ergosterol, the main constituent of cell membranes, as well as certain enzymes. It is specific for fungi, as mammalian cell membranes contain no ergosterol.
Sensitive fungi Ketoconazole inhibits growth of dermatophytes and yeast species (such as Candida albicans).
Phenobarbital (Luminal): for generalized tonic-clonic and partial seizures (not used for absence seizures)
Mechanism: enhances GABA inhibition (↑ open time of Cl channels in presence of GABA)
Side effects: sedation, ataxia, cognitive impairment, induction of hepatic microsomal enzymes
Neurophysiology
Nerve fibers exhibit wide range of sensitivity to nerve blockade-in order of increasing resistance to block are the sensations of pain, cold, warmth, touch, pressure, proprioception and motor function
Nerve Fibers:
Types |
Size |
Speed |
Occurrence |
A (α) |
20 µm |
80 - 120 |
Myelinated (Primarily for muscular activity). |
β |
8 - 15 µm |
|
Myelinated (Touch and pressure) |
γ |
4 - 8 µm |
|
Myelinated (Muscle spindle tone) |
δ |
3 - 4 µm |
10-15 |
Myelinated (Pain and temperature sensation) |
B |
4 µm |
10-15 |
Myelinated (Preganglionic autonomic) |
C |
1-2 µm |
1 - 2 |
Unmyelinated (Pain and temperature sensation) |
Myelinated = faster conducting
Unmyelinated = slower conducting
- Small non-myelinated fibers (C- pain fibers) and smaller myelinated pre-ganglionic B fibers are more readily blocked than are larger myelinated fibers responsible for muscle activity and touch [A-alpha and A-beta].
- Clinically, a person would notice complete lack of sensation to a pinprick, while at the same time still be able to move their fingers.
Fluconazole: an antifungal used orally, intravenously or vaginally to treat yeast and fungal infections. Side-effects of systemic administration include hepatotoxicity (liver damage).
- For vaginal candidiasis (vaginal thrush), a once-only oral dose is often sufficient.
Dextromethorphan
O-methylated dextrorphan, Excellent oral antitussive, No analgesic effect, No GI effects, No respiratory depression
Adverse effects
Nitrates
– Headache, hypotension, dizziness, lightheadedness, tachycardia, palpitations
Beta-adrenergic blocking agents
– hypotension, bradycardia, bronchospasm, congestive heart failure
Calcium channel blockers
– hypotension, dizziness, lightheadedness, weakness, peripheral edema, headache, congestive heart failure, pulmonary edema, nausea, and constipation
Drugs that increase effects of Antianginal drugs
• Antihypertensive
• Diuretics
• Phenothiazine antipsychotic agents
• Cimetidine
• Digoxin
Drugs that decrease effects of Antianginal
• Adrenergic drugs - epinephrine
• Anticholinergic
• Calcium salts
• Phenobarbital, Phenytoin
Adjunctive Antianginal Drugs
In addition to antianginal drugs, several other drugs may be used to control risk factors and prevent progression of myocardial ischemia to myocardial infarction and sudden cardiac death.
These may include:
• Aspirin. This drug has become the standard of care because of its antiplatelet (ie, antithrombotic) effects. Recommended doses vary from 81 mg daily to 325 mg daily or every other day; apparently all doses are beneficial in reducing the possibility of myocardial reinfarction, stroke, and death. Clopidogrel 75 mg/day,
Is an acceptable alternative for individuals with aspirin allergy.
• Antilipemics. These drugs may be needed by clients who are unable to lower serum cholesterol levels sufficiently with a low-fat diet. Lovastatin or a related “statin” is often used. The goal is usually to reduce the serum cholesterol level below 200 mg/dL and lowdensitylipoprotein cholesterol to below
130 mg/dL.
• Antihypertensives. These drugs may be needed for clients with hypertension. Because beta blockers and calcium channel blockers are used to manage hypertension as well as angina, one of these drugs may be effective for both disorders.
EPHEDRINE
It act indirectly and directly on α and β receptors. It increases blood pressure both by peripheral vasoconstriction and by increasing the cardiac output. Ephedrine also relaxes the bronchial smooth muscles.
Ephedrine stimulates CNS and produces restlessness, insomnia, anxiety and tremors.
Ephedrine produces mydriasis on local as well as systemic administration.
Ephedrine is useful for the treatment of chronic and moderate type of bronchial asthma, used as nasal decongestant and as a mydriatic without cycloplegia. It is also useful in preventing ventricular asystole in Stokes Adams syndrome.