Pharmacology: Pharmacodynamics: Miconazole contains Miconazole, an imidazole derivative antifungal drug. Miconazole has a broad spectrum of activity and is particularly effective against pathogenic fungi and yeasts including Candida albicans. In addition, it is effective against gram-positive bacteria.
Miconazole shows its effect during ergosterol synthesis present on cell cytoplasmic membrane. Miconazole changes permeability of mycotic cell Candida species in vitro and inhibits the glucose consumption of the cell.
Pharmacokinetics: Absorption: Miconazole persists in the vagina for up to 72 hrs after a single dose. Systemic absorption of Miconazole after intravaginal administration is limited, with a bioavailability of 1-2% following intravaginal administration of a 1.2 g dose. Plasma concentrations of Miconazole are measurable within 2 hrs of administration in some subjects, with maximal levels seen 12-24 hrs after administration. Plasma concentrations decline slowly, thereafter and were still measurable in most subjects 96 hrs post-dose. Absorption of Miconazole by the intravaginal route is very low (approximately 1.4% of dose).
Distribution: Following the insertion of vaginal suppository containing Miconazole 1.2 g in a single dose, the average maximum serum concentration is 10.4 mcg/L, and the elimination half-life (t½) is 56.8 hrs. The average serum concentration-time curve has been calculated to be 967 mcg/L/hr. Protein-binding ratio is between 90% and 93%.
Biotransformation: It is metabolized in liver microsomally. There are no active metabolites. The major metabolite formed by oxidative-N-dealkylation is 2,4-diclorophenile-1 H imidazole ethanol and secondary metabolite is oxidative 2,4-dicloromandelic acid by O-dealkylation.
Elimination: Half-life is 24 hrs. Less than 1% is excreted in the urine. Approximately 50%, is usually excreted with feces as unchanged drug.
Keep Miconazole away from the eyes.
Apply enough Miconazole to cover the affected area, and rub in gently.
To use the aerosol powder form of Miconazole:
To use the aerosol solution form of Miconazole:
To use the powder form of Miconazole:
When Miconazole is used to treat certain types of fungus infections of the skin, an occlusive dressing (airtight covering, such as kitchen plastic wrap) should not be applied over Miconazole. To do so may cause irritation of the skin. Do not apply an occlusive dressing over Miconazole unless you have been directed to do so by your doctor.
To help clear up your infection completely, keep using Miconazole for the full time of treatment, even if your condition has improved. Do not miss any doses.
The dose of Miconazole will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of Miconazole. If your dose is different, do not change it unless your doctor tells you to do so.
The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.
If you miss a dose of Miconazole, apply it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule.
Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Keep from freezing.
Store the canister at room temperature, away from heat and direct light. Do not freeze. Do not keep Miconazole inside a car where it could be exposed to extreme heat or cold. Do not poke holes in the canister or throw it into a fire, even if the canister is empty.
Keep out of the reach of children.
Do not keep outdated medicine or medicine no longer needed.
Use exactly as prescribed by your doctor. Do not use in larger or smaller amounts or for longer than recommended. Follow the directions on your prescription label.
Miconazole buccal is used each morning for 14 days in a row. Follow your doctor's instructions.
Brush your teeth before putting in a buccal tablet. Make sure your hands are dry before handling the tablet.
Place the rounded side of the tablet against your upper gum near your back teeth. Close your mouth and press your finger gently against the side of your cheek for 30 seconds to make sure the tablet stays in place.
Leave the tablet in place until the next morning. Switch the sides of your mouth each morning when using a new tablet.
If any pieces of the tablet remain in your mouth the next morning, rinse your mouth with water before using a new tablet.
Do not crush, chew, or break a Miconazole buccal tablet. Do not swallow the tablet whole.
You may eat and drink normally while the tablet is in place, but avoid chewing gum.
During the first 6 hours after placing a buccal tablet in your mouth, if the tablet comes loose try putting it back into place. If it still comes loose, put in a new tablet. If you accidentally swallow a tablet within the first 6 hours of wearing time, drink a full glass of water and put in a new tablet.
After the first 6 hours, if a tablet comes loose or you accidentally swallow it, do not put in a new tablet. Wait until it is time for your next dose to put in a new tablet.
Store at room temperature away from moisture and heat.
Miconazole is an antifungal drug [ see Clinical Pharmacology (12.4)].
Absorption and Distribution
Single dose application of Miconazole containing 50 mg of Miconazole to the buccal mucosa of 18 healthy volunteers provided mean maximum salivary concentrations of 15 mcg/mL at 7 hours after application of the tablet. This provided an average saliva exposure to Miconazole estimated from the AUC (0-24h) of 55.23 mcg⋅h/mL. The pharmacokinetic parameters of Miconazole in the saliva of healthy volunteers are provided in Table 4.
|Salivary PK |
Parameters (N = 18)
|Mean ± SD |
(Min - Max)
|AUC0-24h (mcg-h/mL)||55.2 ± 35.1 |
(0.5 – 128.3)
|Cmax (mcg/mL)||15.1 ± 16.2 |
(0.5 – 64.8)
|Tmax (hour)||7* |
(2.0 – 24.1)
In healthy volunteers, the duration of buccal adhesion was on average 15 hours following a single dose application of Miconazole 50 mg.
Plasma concentrations of Miconazole were below the lower limit of quantification (0.4 mcg/mL) in 157/162 (97%) samples from healthy volunteers following single-dose application of Miconazole 50 mg. Measurable plasma concentrations ranged from 0.5 to 0.83 mcg/mL.
Plasma concentrations of Miconazole evaluated after 7 days of treatment in 40 HIV-positive patients were all below the limit of quantification (0.1 mcg/mL).
Metabolism and Excretion
Most of the absorbed Miconazole is metabolized by the liver with less than 1% of the administered dose found unchanged in urine. In healthy volunteers, the terminal half-life is 24 hours following systemic administration. There are no active metabolites of Miconazole.
There was no formal food effect study conducted with Miconazole; however, in clinical studies patients were allowed to eat and drink while taking Miconazole.
Mechanism of Action
Miconazole inhibits the enzyme cytochrome P450 14α-demethylase which leads to inhibition of ergosterol synthesis, an essential component of the fungal cell membrane. Miconazole also affects the synthesis of triglycerides and fatty acids and inhibits oxidative and peroxidative enzymes, increasing the amount of reactive oxygen species within the cell.
Activity in vitro and in vivo
Miconazole is active against Candida albicans, C. parapsilosis, and C. tropicalis. Correlation between minimum inhibitory concentration (MIC) results in vitro and clinical outcome has yet to be established.
In vitro studies have shown that some Candida strains that demonstrate reduced susceptibility to one antifungal azole may also exhibit reduced susceptibility to other azoles suggesting cross-resistance.
Clinically relevant resistance to systemically utilized triazoles may occur in Candida species. Resistance may occur by multiple mechanisms such as changes in amino acids and/or in the regulation of the target enzyme and of a variety of efflux pump proteins. Multiple mechanisms may co-exist in the same isolate. Resistance breakpoints, correlating in vitro activity with clinical efficacy, have not been established for Miconazole.
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Information checked by Dr. Sachin Kumar, MD Pharmacology