Q. 2. Corticosteroids in dentistry.
Ans. Corticosteroids are the hormones produced by the cortex of the adrenal gland. They are as follows:
• A small amount of androgens.
The secretion of adrenal cortex is under the control of ACTH secreted by the anterior pituitary, which in turn is regulated by corticotropin releasing factor (CRF). This is termed as hypothalamic−pituitary−adrenal axis.
Classification of corticosteroids
A. Short acting (8−12 hours)
B. Intermediate acting (18−36 hours)
C. Long acting (36−54 hours)
Mechanism of action
Corticosteroids bind to specific receptors in the cytoplasm, the drug−receptor complex is transported into the nucleus where it binds to specific sites on DNA and regulates the synthesis of new proteins that bring about the hormone effects.
• Synthetic corticosteroids are more selective corticosteroids. They do not have mineralocorticoid action.
• They are more potent than the natural corticoids. They generally have intermediate to long duration of action.
• Synthetic glucocorticoids include:
• It is more selective glucocorticoid and is four times more potent than hydrocortisone.
• Used for allergic, inflammatory, autoimmune diseases and in malignancies.
• For example, available as DELTACORTRIL, HOSTACORTIN-H,5,10 mg tab, 20 mg/mL for i.m., intraarticular injection, WYSOLONE, NUCORT, 5, 10, and 20 mg tab.
• Slightly more potent and more selective than prednisolone; 4−32 mg/day oral.
• For example, available as SOLU-MEDROL methylprednisolone (as sodium succinate) 0.5 g (8 mL) and 1.0 g (16 mL) injection for i.m., slow i.v. injection.
• Slightly more potent but highly selective glucocorticoid than prednisolone: 4−32 mg/day oral, 5−40 mg i.m., intraarticular injection. Also used topically.
• For example, available as KENACORT, TRICORT 1, 4 and 8 mg tab., 10 mg/mL, 40 mg/ml (as acetonide) for i.m., intraarticular injection LEDERCORT 4 mg tab.
• Very potent and highly selective glucocorticoid than prednisolone. It is used for inflammatory and allergic conditions in a dose of 0.5–5 mg/day oral. In shock, cerebral oedema, etc. 4−20 mg/day IV, IM, injection. Also used topically.
• For example, available as DECADRON, DEXONA 0.5 mg tab, 4 mg/mL (as sodium phosphate) for IV, IM, injection, 0.5 mL oral drops, etc.
• Same as that of dexamethasone: 0.5–5 mg/day oral, 4−20 mg/day IV, IM, injection or infusion, also topical.
• For example, available as BETNESOL, BETACORTRIL, CELESTONE 0.5 mg, 1 mg tab and 4 mg/mL (as sodium phosphate) for IV, IM, injection, 0.5 mL oral drops, etc.
Most of the adverse effects of glucocorticoids are extension pharmacological actions and are dependent on dose, duration of therapy and the relative potency of additional mineralocorticoid effects.
i. Cushing syndrome: Abnormal fat distribution causes moon face, buffalo hump, truncal obesity, muscle wasting, thinning of limbs and skin, easy brushing, purple striae and acne.
ii. Hyperglycaemia: Precipitation of diabetes mellitus or aggravation of preexisting diabetes.
iii. Susceptibility of infection: Long-term therapy with steroids leads to immunosuppression, which makes the patient more vulnerable to various opportunistic infections like fungal, viral and bacterial, etc.
iv. Osteoporosis: Especially of the vertebrae is more common in the elderly.
v. Avascular necrosis: Avascular necrosis of the bone due to restriction of blood flow through bone capillaries may cause pain and restriction of movement. Growth in children may be suppressed.
vi. Peptic ulceration: This may sometimes occur on prolonged therapy especially when other ulcerogenic drugs are (e.g., NSAIDs) used concurrently.
vii. Mental disturbance: Include euphoria, psychosis and depression.
viii. Eye: Cataract and glaucoma may occur on prolonged therapy.
ix. Delayed wound healing.
x. Other effects: Raised intracranial pressure, convulsions, hypercoagulability of the blood and menstrual disorders.
xi. Mineralocorticoid effects: This includes salt and water retention, oedema, hypokalaemia and hypertension are rare with selective glucocorticoids.
xii. Thinning of muscles: Steroid treatment can cause hypokalaemia leading to muscle weakness and fatigability. Long-term steroid therapy leads to steroid myopathy.
xiii. HPA axis suppression: The most undesirable and dangerous outcome of long-term steroid therapy leads HPA axis suppression.
Q. 1. Metronidazole.
• Metronidazole is a potential agent for local antimicrobial therapy due to its selective antimicrobial features against the obligate anaerobes.
• The most extensively tested and used device for metronidazole application is a gel consisting of a semisolid suspension of 25% metronidazole benzoate in a mixture of glyceryl mono-oleate and sesame oil (Elyzol Dental Gel, Dumex, Copenhagen, Denmark). Applied with a syringe inserted into the pocket, the gel increases in viscosity after placement.
• Metronidazole is a nitroimidazole compound used to treat protozoal infections. It is bactericidal to anaerobic organisms.
• Although metronidazole is not the drug of choice for treating A. actinomycetemcomitans infections, it may be effective at therapeutic levels because of its hydroxy metabolite. When used in combination with other antibiotics metronidazole is effective against A. actinomycetemcomitans.
• Metronidazole is also effective against anaerobes such as Porphyromonas gingivalis and Prevotella intermedia.
• Metronidazole has been used clinically to treat gingivitis, acute necrotizing ulcerative gingivitis (NUG), chronic periodontitis and aggressive periodontitis.
• A single dose of metronidazole (250 mg orally) appears in both serum and GCF in sufficient quantities to inhibit a wide range of suspected periodontal pathogens.
• Administered systemically (750−1000 mg/day for 2 weeks), metronidazole reduces the growth of anaerobic flora, including spirochetes, and decreases the clinical and histopathologic signs of periodontitis.
• The most common regimen is 250 mg three times daily (t.i.d.) for 7 days.
• A topical medication containing an oil-based metronidazole 25% dental gel (glyceryl mono-oleate and sesame oil) has been tested in a number of studies.
• As a precursor, the preparation contains metronidazole-benzoate, which is converted into the active substance by esterases in GCF.
• Metronidazole has an antiabuse effect when alcohol is ingested, resulting in severe cramps, nausea and vomiting. Hence, products containing alcohol should be avoided during therapy and for at least 1 day after therapy is discontinued.
• Metronidazole also inhibits warfarin metabolism. Patients undergoing anticoagulant therapy should avoid metronidazole because it prolongs prothrombin time.
• It also should be avoided in patients who are taking lithium.
Q. 2. Oral penicillin.
Classification and uses of oral penicillins.
Uses and side-effects of oral penicillins.
• Antibiotic is a chemical substance produced by a microorganism, which has the capacity to inhibit the growth or kill other organism in dilute solution.
• Penicillin is the most important and the first antibiotic to be used, obtained from a fungus of penicillium notatum, but the yield was very low. The present source of pencillin is the high-yielding P. chrysogenum.
• Benzyl penicillin (penicillin G)
i. Acid-resistant penicillins
• Phenoxymethyl penicillin (penicillin V)
ii. Penicillinase-resistant penicillins
iii. Extended spectrum penicillins
• Carbenicillin indanyl
• Carbenicillin phenyl (carfecillin)
• Mecillinam (Amdinocillin)
• Clavulanic acid
i. Penicillin G or benzyl penicillin is the drug of choice for infection caused by bacteria susceptible to it, that is Streptococci, Pneumococci, Bacillus anthracis, Corynebacterium diphtheriae, Clostridia, Listeria, Spirochetes and Neisseria species.
a. Streptococcal infections:
i. Pharyngitis, otitis media, scarlet fever, rheumatic fever. 0.5−5 MU i.v. 8 hourly for 7−10 days.
ii. Subacute bacterial endocarditic caused by Step. viridans or faecalis. 10−20 MU i.v. daily with streptomycin 0.5 g 1M BD for 2−6 weeks.
b. Pneumococcal infections:
Though not recommended but can be given if organisms is sensitive. 3–6 MU i.v. every 6 hourly.
c. Meningococcal infections:
Respond well to high dose of penicillins.
i. Penicillins have been taken over by fluoroquinolones/ceftriaxones as the first line drugs. However, it can be used in NPPG infection as 4.8 MU i.m. single dose divided and given in both buttocks or procaine penicillin with Ig probenecid orally.
ii. For ophthalmia neonatorum due to sensitive N. gonorrhoeae.
• Saline irrigation + 1 drop containing 10,000−20,000 U/mL of sodium penicillin G in each eye every 1−2 hours for 1 week.
• In severe cases, give 50,000 U i.m. BD in addition.
Penicillin G is the drug of choice for syphilis.
i. Early and latent syphilis
1.2 MU of procaine penicillin daily for 10 days (Or) 2.4 MU of benzathine penicillin weekly for 1−3 weeks.
ii. Late syphilis
2.4 MU of benzathine penicillin weekly for 4 weeks.
5 MU i.m. of sodium penicillin G 6 hourly for 2 weeks.
Penicillin treatment is of adjuvant value to antitoxin therapy and prevents carrier state.
1−2 MU of procaine penicillin daily for 10 days.
g. Tetanus and gas gangrene:
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