Abstract

This comprehensive report evaluates the quality control and pharmacological profile of Terbinafine tablets, ensuring adherence to Indian Pharmacopoeia (IP) 2022 standards. 1. Identity: Thin Layer Chromatography (TLC) confirmed the presence of Terbinafine. 2. Physical Characteristics: Tablets met IP 2022 specifications for description and disintegration time (?15 minutes). 3. Chemical Purity: Assay results showed 97.06% of labeled amount. 4. Performance: Dissolution exceeded 75% in 30 minutes. 5.Microbial limits. 6. Assay: 90-110% of labeled amount. Pharmacological Assessment: 1. Mechanism: The synthesis of fungal cell membranes is disrupted by squalene epoxidase inhibition. 2. Antimicrobial Spectrum: Works well against molds, yeasts, and dermatophytes. 3. Pharmacokinetics: Hepatic metabolism, wide tissue distribution, and quick absorption. Limits of Microbes: met IP 2022 requirements for the absence of designated pathogens, total yeast and mold count (TYMC), and total aerobic microbiological count (TAMC). Limits of Microbes.

Keywords

Terbinafine, Quality Control, Pharmacopeial Standards, Antifungal, Squalene Epoxidase Inhibition.

Introduction

In India, fungal infections pose a serious healthcare risk to millions of people from a wide range of demographic backgrounds. The severity of these illnesses varies; simple skin infections like ringworm and athlete's foot can be followed by more serious systemic infections that can be fatal, especially to those with weakened immune systems. The country of India has a tropical and subtropical climate, which is perfect for the growth of fungi and increases the occurrence of fungal illnesses. These illnesses also spread because of things like inadequate cleanliness, the widespread use of antibiotics, and close quarters in densely populated places.

In India, terbinafine, a strong antifungal drug, is frequently prescribed to treat dermatophytic infections. It works very well against many types of fungus, especially those that cause infections in the skin, hair, and nails. Terbinafine works by preventing the creation of ergosterol, an important component of fungal cell membranes, by blocking the enzyme squalene epoxidase. Squalene builds up as a result of this enzyme's inhibition, which is harmful to fungal cells and ultimately results in cell death. Because of its mode of action, Terbinafine is very useful in the treatment of diseases including athlete's foot, ringworm, and onychomycosis, which are fungal nail infections.

This review's goal is to determine whether Terbinafine tablets adhere to the guidelines provided by the Indian Pharmacopoeia. This review attempts to highlight the significance of following these guidelines by looking at the outcomes of several quality control tests. These guidelines are essential for preserving the quality, safety, and efficacy of Terbinafine tablets in the Indian pharmaceutical market. ^[1,2,3,4]

4) Pharmacopeial standards-

The official manual for guaranteeing the effectiveness, safety, and quality of medications in India is the Indian Pharmacopoeia (IP). The Indian Pharmacopoeia Commission (IPC) publishes it, and it offers thorough standards and instructions for evaluating pharmaceutical items, both completed and raw^.[1]

5) Structure:  Terbinafine

       
           
       

1) IUPAC Name: (E)-N-(6,6-Dimethyl-2-hepten-4-in-4-yl)-N-methyl-1-naphthalenemethylamine

2) Alternative Names:

1. Terbinafine hydrochloride (USP)

2. Lamisil (proprietary name)

3. Terbinam (INN)

3) Chemical Structure: C₂₁H₂₅N

4) Molecular Weight: 291.43 g/mol

5) Pharmacological Classification:

Antifungal agent, squalene epoxidase inhibitor.

6) QUALITY CONTROL TEST:

6.1) Identity Tests:

1. Thin Layer Chromatography (TLC) (IP 2022, Vol. 3, Page 3759)

6.2) Physical Characteristics:

1. Description: White or almost white, circular, biconvex tablets (IP 2022, Vol. 3, Page 3756)

2. Disintegration Time: ?15 minutes (IP 2022, Vol. 3, Page 3456)

6.3) Chemical Tests:

1. Assay: 90-110% of labeled amount (IP 2022, Vol. 3, Page 3759)

6.4) Performance Tests:

1. Dissolution: ?75% in 30 minutes (IP 2022, Vol. 3, Page 3758)

6.5) Microbial limits:

6.1) Identity Test:

1)Thin Layer Chromatography (TLC) (IP 2022, Vol. 3, Page 3758)

TABLET DETAILS: Terbinafine 250mg

Preparation of solutions:

Sample solution:

1. Weigh 0.5 g of powdered terbinafine tablet.
2. Then dissolve in 10 mL of methanol.
3. After that filter and use the filtrate for spotting.

 Standard solution:

     1.Weigh 10 mg of pure terbinafine.

     2.Dissolve in 10 mL of methanol (resulting in 1 mg/mL concentration).

Mobile Phase:

Mobile Phase Composition: Ethyl acetate: Methanol: Ammonia = 85:10:5.

 

Spots on TLC Plate:

Spot 5 µL of the sample solution and 5 µL of the standard solution onto the TLC plate.

Development and Results:

After development, measure the distance traveled by each spot and the solvent front.

---

Spot	Distance travelled by spot (cm)	Distance travelled by solvent front(cm)	Rf value
Standard (Terbinafine)	3.5	7	0.50
Sample (Terbinafine)	3.4	7	0.49

---

Rf Calculation:

Rf value =

Distance traveled by the spot / Distance traveled by the solvent front

For the Standard (terbinafine):

Rf value = 3.5 cm /7cm = 0.50

For the Sample (terbinafine):

1. 4. cm /7 cm = 0.49 

Interpretation:
The fact that the Rf values of the standard terbinafine and the sample are nearly equal suggests that the tablet's active component is the same as that of the standard terbinafine.
The marginal variation in Rf values (0.01) falls within a reasonable experimental error margin.

CONCLUSION

The close Rf values between the sample and standard in the TLC analysis demonstrate that the terbinafine tablet contains the proper active component.
The absence of new spots indicates that there aren't any noticeable contaminants present^{. [1,2,4,5]}

6.2) Physical Characteristics:

1. Description (Terbinafine Tablets in (IP) 2022 volume- 03: Monograph: Terbinafine Tablets Page: 3456-3459):

 

The following are the description and tests for Terbinafine Tablets as per Indian       Pharmacopoeia (IP) 2022:
1) White or almost white

2) Circular

3) Biconvex ^[1,2]

2. Disintegration Time: ?15 minutes (IP 2022, Vol. 3, Page 3456)

Equipment:  Disintegration test equipment (basket-rack arrangement)

Medium: Water or simulated gastric fluid (pH 1.2) or simulated intestinal fluid (pH 6.8)

Method:
1. Insert one tablet into each of the basket-rack assembly's six tubes.
2. Fill the tubes with the designated medium (water, for example).
3. Conduct the experiment at 37 ± 2°C.
4. Check the tablets at predetermined intervals for disintegration.

---

Tablet No.	Disintegration Time (minutes)
0	0
1	10
2	12
3	11

---

Avg. Disintegration Time = (10 + 12 + 11) / 3 = 11 minutes

Acceptance criterion: Within fifteen minutes, the tablet should totally dissolve.

Results:

The tablets meet IP 2022 requirements because their average disintegration time of 11 minutes is shorter than 15 minutes. [1,2,6,7,8]

6.3) Chemical Tests:

1. Assay: 90-110% of labeled amount (IP 2022, Vol. 3, Page 3457)

Apparatus:

1. UV Spectrophotometer
2. Quartz cells (1 cm)

2. Sonicator
3. Centrifuge
4. Pipettes

Reagents:

1) Terbinafine Hydrochloride Reference Standard

2) Methanol

 3) 0.1 M Hydrochloric acid

4) Distilled water

Procedure:

Preparation of Standard Solution:

1. Weigh the Terbinafine Hydrochloride Reference Standard (50 mg) precisely.
2. Pour into a volumetric flask that holds 100 mL.
3. Include 50 mL of methanol.
4. Sonicate for half an hour.
5. Use distilled water to dilute to 100 mL (Concentration(cstd): 50?g/mL

Preparation of Test Solution:

1. 1. Weigh accurately 20 tablets.
   2. Powder the tablets.
   3. Weigh accurately a portion of the powder equivalent to 50 mg of Terbinafine Hcl
   4. Transfer to a 100 mL volumetric flask.
   5. Add 50 mL of methanol.
   6. Sonicate for 5 minutes.
   7. Dilute to 100 mL with distilled water.(Concentration (Ctest): 50 ?g/mL)
   8. Centrifuge at 3000 rpm for 5 minutes.

Measurement:

1. Measure the absorbance of standard and test solutions at 224 nm using UV Spectrophotometer.

2. Use 0.1 M Hydrochloric acid as blank.

Assay Calculation:

1. Calculate the content of Terbinafine Hydrochloride using the formula:

Content (%) = (Absorbance test / Absorbance std) x (Cstd / Ctest) x 100

    Where: (Cstd /Ctest)- concentration ratio of test /standard

UV Spectrophotometry:

---

Wavelength	224 nm
Absorbance std.	0.850
Absorbance test	0.825

---

Calculation:

Content (%) = (Absorbance test / Absorbance std) x (Cstd / Ctest) x 100

Content (%) = (0.825 / 0.850) x (50 ?g/mL / 50 ?g/mL) x 100

Content (%) = 97.06%

Results:

Terbinafine Hydrochloride content: 97.06% of labeled amount

 Result: Complies (within 90-110% of labeled amount) [1,6,7,8,]

6.4) Performance Tests:

1. Dissolution: ?75% in 30 minutes (IP 2022, Vol. 3, Page 3457)

Apparatus:

1. UV Spectrophotometer

2. Quartz cells (1 cm)

3. Vortex mixer

4. Sonicator

5. Centrifuge

6. Pipettes

Reagents:

1. Terbinafine Hydrochloride Reference Standard

2. Methanol

3. 0.1 M Hydrochloric acid

4. Distilled water

Procedure:

Preparation of Standard Solution:

1. Weigh accurately 50 mg of Terbinafine Hydrochloride Reference Standard.

2. Transfer to a 100 mL volumetric flask.

3. Add 50 mL of methanol.

4. Sonicate for 5 minutes.

5. Dilute to 100 mL with distilled water.

Preparation of Test Solution:

1. Weigh accurately 20 tablets.

2. Powder the tablets.

3. Weigh accurately a portion of the powder equivalent to 50 mg of Terbinafine Hydrochloride.

4. Transfer to a 100 mL volumetric flask.

5. Add 50 mL of methanol.

6. Sonicate for 5 minutes.

7. Dilute to 100 mL with distilled water.

8. Centrifuge at 3000 rpm for 5 minutes.

UV Spectrophotometry:

1. Measure the absorbance of standard and test solutions at 224 nm using UV Spectrophotometer.

2. Use 0.1 M Hydrochloric acid as blank.

---

	Standard solution	Test solution
Concentration	50 ?g/mL	50 ?g/mL
Absorbance	0.850	0.825

---

Calculation:

Content (%) = (Absorbance test / Absorbance std) x (Cstd / Ctest) x 100

Content (%) = (0.825 / 0.850) x (50 ?g/mL / 50 ?g/mL) x 100

Content (%) = 97.06%

Results:

Terbinafine Hydrochloride content: 97.06% of labeled amount

 Result:  Complies (within 90-110% of labeled amount)

Acceptance Criteria:

 90-110% of labeled amount [1,4,6,8]

6.5) Microbial Limits:

1. Total Aerobic Microbial Count (TAMC): Not more than 10^3 CFU/g

2. Total Yeast and Mold Count (TYMC): Not more than 10^2 CFU/g

3. Escherichia coli (E. coli): Absent

4. Salmonella: Absent

5. Pseudomonas aeruginosa: Absent

6. Staphylococcus aureus: Absent

7. Candida albicans: Absent

Acceptance Criteria:

If the TAMC is less than 10^3 CFU/g, the article passes the test.

- There are no more than 10^2 CFU/g in the TYMC.
- No particular microorganism is found.

Sampling:
To prevent contamination, take a representative sample of the Terbinafine pills or powder and handle it sterilely. [1,2,15,19,25]

7) Mechanism of terbinafine tablet

Step 1: Inhibition of Squalene Epoxidase

1. Terbinafine binds to the active site of squalene epoxidase, a fungal enzyme.

2. This binding prevents substrate (squalene) binding and enzyme activity.

3. Squalene epoxidase is essential for converting squalene to lanosterol. [9,13,18,22,25,]

Step 2: Disruption of Ergosterol Synthesis

1. Inhibition of squalene epoxidase leads to accumulation of squalene.

2. Lanosterol and ergosterol levels decrease due to blocked conversion.

3. Ergosterol is essential for fungal cell membrane integrity. [9,18,19,]

Step 3: Cell Membrane Damage

1. Accumulated squalene disrupts cell membrane fluidity and permeability.

2. Loss of cellular contents (e.g., ions, amino acids) occurs.

3. Fungal cell membrane becomes unstable. [13,18,24]

Step 4: Fungal Cell Death

1. Apoptosis (programmed cell death) or necrosis (cellular damage) ensues.

2. Terbinafine fungicidal activity kills fungal cells. [9,10,12]

Biochemical Pathway

1. Squalene ? Lanosterol (inhibited by terbinafine)

2. Lanosterol ? Ergosterol (depleted)

3. Ergosterol ? Cell membrane synthesis (disrupted)

4. Cell membrane ? Fungal cell viability (compromised) [9,14,18,22]

Molecular Interactions

Target Protein

1. Squalene epoxidase (enzyme)

2. Terbinafine binds to the enzyme's active site [21,24,26]

Protein Structure

1. Terbinafine interacts with key amino acids (e.g., histidine, aspartate)

2. Hydrophobic interactions stabilize terbinafine binding. [9,12]

8) Resistance Mechanisms

A) Mutations

1. Squalene epoxidase gene mutations reduce terbinafine binding

2. Enzyme overexpression increases IC50 values

B) Changes in Cell Membrane Composition

1. Altered lipid composition reduces terbinafine uptake

2. Increased efflux pumps remove terbinafine [13,14,20]

9) Combination Therapies

A) Terbinafine + Other Antifungals

1. Terbinafine + Amphotericin B: Enhanced efficacy against Candida and Aspergillus.

2. Terbinafine + Fluconazole: Improved treatment outcomes for onychomycosis.

3. Terbinafine + Itraconazole: Increased efficacy against dermatophytes.

4. Terbinafine + Voriconazole: Broad-spectrum activity against fungal infections.

 B) Terbinafine + Immunomodulators

1. Terbinafine + Interferon-?: Enhanced immune response against fungal infections.

2. Terbinafine + Granulocyte-macrophage colony-stimulating factor (GM-CSF): Improved neutrophil function.

3. Terbinafine + Tumor necrosis factor-? (TNF-?) inhibitors: Modulated immune response. [9,10,12,18,22]

10) Contraindications

1. Terbinafine hypersensitivity
   Definition: Severe terbinafine allergic responses.
   Hives, itching, swelling, trouble breathing, and a fast heartbeat are some of the symptoms.
   Risk factors include a history of eczema, asthma, or allergies.
   The result is potentially fatal anaphylaxis.
   Steer clear of terbinafine as a precaution.
2.  Severe impairment of the liver

 - Definition: Child-Pugh Class C, or advanced liver disease.
Hepatitis, liver cancer, and cirrhosis are risk factors.
- Repercussions: Terbinafine makes liver damage worse.
Keep an eye on liver function tests (LFTs) as a precaution.

3. Lactation and pregnancy (Category B)

Pregnancy:
Definition: Possible danger to the fetus.
Risk factors: Exposure during the first trimester.
Implications include prenatal poisoning and deformities of the limbs.
Use caution and only if the advantages outweigh the risks.

Terbinafine is expelled in breast milk during lactation.
Exposure of infants is a risk factor.
Potential damage to a nursing infant is one of the consequences.
Precaution: Stop taking terbinafine or refrain from nursing. [1,10,12,16,18]

11) Conclusion:

The Indian Pharmacopoeia (IP) 2022's pharmacopeial requirements are met by the Terbinafine Tablets that were tested. The quality control test results show that the tablets fulfill the necessary requirements for

A) Identity Tests:

1. Thin Layer Chromatography (TLC) (IP 2022, Vol. 3, Page 3759)

B) Physical Characteristics:

1. Description: White or almost white, circular, biconvex tablets (IP 2022, Vol. 3, Page 3756)

2. Disintegration Time: ?15 minutes (IP 2022, Vol. 3, Page 3456)

C) Chemical Tests:

2. Assay: 90-110% of labeled amount (IP 2022, Vol. 3, Page 3759)

D) Performance Tests:

1. Dissolution: ?75% in 30 minutes (IP 2022, Vol. 3, Page 3758)

E) Microbial limits

The active ingredient, Terbinafine Hydrochloride, has pharmacological characteristics that guarantee the treatment of fungal infections. By blocking squalene epoxidase, the medication prevents the production of fungal cell membranes.
Statement of Compliance
The IP 2022 standards are met by this batch of Terbinafine tablets, attesting to their effectiveness, quality, and purity for medicinal use.

F) Pharmacology:

Strong antifungal agent terbinafine prevents the production of fungal cell membranes by blocking squalene epoxidase. Among the pharmacological profile of it are:

- Effective against mold, yeast, and dermatophytes
- Quick absorption and wide-ranging tissue dispersion
Potential medication interactions with CYP2C9 inhibitors; severe hepatic impairment and pregnancy; hepatic metabolism and renal excretion;
Terbinafine is an effective treatment for fungal infections, especially dermatophytosis and onychomycosis, due to its distinct mechanism and pharmacokinetic characteristics.

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