Some of the important parameters are stability testing, safety assessment, specific therapeutic activity analysis and estimation of active constituents in the plant raw material and finished products. The objective of WHO guidelines is to define basic criteria for the evaluation of quality, safety and efficacy of herbal medicines^[6].

Stability:

Inadequate storage and distribution of pharmaceutical / herbal products can lead to their physical deterioration and chemical decomposition, resulting in reduced activity and occasionally, in the formation of toxic degradation products. Degradation is particularly likely to occur under tropical conditions of high ambient temperature and humidity. It is because of the potential for chemical interaction between the active ingredients and excipients, that the drug dosage forms can be more vulnerable to degradation than pure drug substances. The stability of a specific product is thus dependent on its formulation, and its expiry date should be determined on the basis of stability studies^[7].

Thus it is clearly understood that the standardization of herbal products is of paramount importance and that stability studies is also one of the major parameter of standardization.

MATERIALS AND METHODS:

The capsules of the polyherbal formulation, Urito were procured from the Research and development center of a renowned private manufacturer of herbal drugs in Chennai i.e.., Rumi Herbals Pvt. Ltd., Mugappair, Chennai. The fresh samples of Urito capsules were taken from those of the Batch no. 1105, manufactured in November 2009, by Rumi Herbals Pvt Ltd, Chennai.

Method:

Accelerated stability studies were carried out under standardized conditions by exposure to air at a temperature of 40 ± 2°C and a relative humidity of 75 ± 5 % in a stability chamber, as per ICH guidelines for Pharmaceutical products^[8]. The study was carried out for a period of 105 days. The appearance of degradation products was detected by means of variation in physical examination, weight of the capsule, loss on drying, total ash content, acid insoluble ash, water soluble extractive, alcohol soluble extractive and estimation of total tannins and mucilage. Various parameters were analyzed during 0, 15^th, 30^th, 45^th, 60^th, 75^th, 90^th and 105^th days respectively as per the methods followed in The Ayurvedic pharmacopoeia^[9,10]. The stability of those parameters was checked by comparing the values obtained for each day sample, as per standard methods^[11,12]. The results obtained were compared with the already attained standard limits for each parameter of the formulation. All the studies were carried out under light excluded conditions, since it is easy to protect substances from light during storage.

RESULTS AND DISCUSSION:

1. Physical examination:

The powder of Urito capsules is a moderately fine powder with the following physical characteristics:

Colour: cream

Odour : characteristic

Taste : slightly bitter

The colour, odour and taste of the formulation were found to be as such and were unchanged throughout the period of study (105 days).

2. Loss on drying:

The samples of Urito were analyzed for their loss on drying values on the 0 day, 15^th, 30^th, 45^th, 60^th, 75^th, 90^th and 105^th days. The change in the moisture content of the formulation was represented by the percentage of loss on drying as shown graphically in the figure 1 and the values were given in table 1. besides the figure 1. Moisture content should not be very high to avoid microbial contamination and degradation of the product.

Table 1. Loss on drying of Urito

Number of days	% Loss On Drying (% w/w)
0	1.33
15	1.35
30	1.42
45	1.45
60	1.48
75	1.51
90	1.54
105	1.55

Figure 1 -Loss on drying of Urito

The moisture content in the formulation was found to be slightly increasing during the study period but it was found to be well within the previously arrived standard value for this parameter i.e., Not More Than 2 % w/w. This suggests that the packing of the product is efficient enough to keep the stability of the polyherbal formulation by preventing the moisture intake.

3. pH:

pH of a product is a very good indicator of degradation or deterioration of the product and also of any changes in the formulation. The pH of Urito samples was tested at regular intervals during the stability studies and the results were represented graphically in Figure 2 with the values shown in table 2.

Table 2. pH of Urito

Number of days	pH
0	5.5
15	5.5
30	5.5
45	5.6
60	5.6
75	5.7
90	5.7
105	5.8

Figure 2. -pH of Urito

The study of changes in pH value of Urito under accelerated conditions has shown that there was a slight increase in the pH from the 45^th day which may be due to the interactions between the contents of the formulation, but the values were within the in-house standard range arrived before which is within 5 - 6.2.

4. Water soluble extractive:

The water soluble extractive value gives the value of the content of the formulation soluble in water. The water soluble content of the samples of Urito were determined periodically during the stability studies of the formulation and were compared with the standard value obtained previously i. e., Not Less Than 9% w/w. The results were represented graphically as in Figure 3.

The values of the water soluble extractive were found to be slightly decreasing during the period of study but the least value obtained on the 105^th day was far above the standard value arrived (NLT 9% w/w). The loss of any volatile content may account for the slight decrease in the water soluble extractive value.

Table 3. Water soluble extractive

Number of days	Water soluble extractive (% w/w)
0	10.81
15	10.78
30	10.65
45	10.61
60	10.54
75	10.32
90	10.26
105	10.19

Figure 3. - Water soluble extractive

5. Alcohol soluble extractive:

The alcohol soluble extractive values were determined for the samples of the formulation at regular intervals of 15 days each time during the stability studies and the results were represented graphically in the Figure 4. with the values in table 4. besides the graph.

Table 4. Alcohol soluble extractive

Number of days	Alcohol soluble extractive (% w/w)
0	15.43
15	15.25
30	15.21
45	15.19
60	15.16
75	15.12
90	15.08
105	15.05

Figure 4 - Alcohol soluble extractive

The alcohol soluble extractive value was also found to slightly decreasing with the increase in the number of days but the values were well above the standard arrived, which is Not Less Than 14% w/w. The reason for this may be same as that for water soluble extractive value.

6. Total ash:

The total ash of a polyherbal formulation determines the amount of inorganic content of the formulation which was also determined for Urito at regular intervals of 15 days during the period of stability studies of the formulation. The results were presented in table 5. and as a graph in the Figure 5.

Table 5. Total ash content

Number of days	Total ash (% w/w)
0	1.4
15	1.4
30	1.39
45	1.41
60	1.38
75	1.4
90	1.42
105	1.42

Figure 5. - Total ash content

The total ash content was found to be stable except for a slight decrease during the 30^th and 60^thdays which may be due to sample variation. None of the values have crossed the standard limit attained i.e., Not More Than 2% w/w.

7. Acid insoluble ash:

The acid insoluble ash value of the formulation determines the purity of the product. The values obtained were plotted in a graph which is shown in Figure 6. There was a very slight variation in the values of the acid insoluble ash but all the values were far below the standard value attained which is Not More Than 0.2% w/w.

8. Total tannin content:

The total tannin content of the polyherbal formulation, Urito was determined at every 15 days interval and the results were represented graphically as in Figure 7. This parameter was selected after the preliminary tests for tannins showed positive results for Urito.

Table 6. Acid insoluble ash content

Number of days	Acid insoluble ash (% w/w)
0	0.153
15	0.153
30	0.154
45	0.156
60	0.155
75	0.156
90	0.156
105	0.158

Figure 6. - Acid insoluble ash content

Table 7. Total tannin content

Number of days	Total tannin content (% w/w)
0	0.0519
15	0.0517
30	0.0517
45	0.0517
60	0.0517
75	0.0516
90	0.0515
105	0.051

Figure 7. - Total tannin content

The total tannin content of the polyherbal formulation was found to be slightly decreasing during the period of stability study but the least value obtained on the 105^th day was above the standard value of total tannin content which is Not Less Than 0.05% w/w. The decrease was found to be very little and was not in significant amounts and thus this parameter was found to be almost stable.

9. Total mucilage content:

The total mucilage content was estimated at regular intervals during the period of stability studies under accelerated conditions. The results obtained were compared with the initial values and were represented graphically in Figure 8 with the values in table 8. Urito, also gave positive result for test for mucilage and so this parameter was considered for stability studies.

Table 8. Total mucilage content

Number of days	Total mucila-ge content (% w/w)
0	4.2
15	4.2
30	4.19
45	4.18
60	4.16
75	4.16
90	4.17
105	4.16

Figure 8. - Total mucilage content

The total mucilage content of the formulation has decreased a little during the period of stability study. The value obtained on the last day did not cross the standard limit arrived previously i.e., Not Less Than 4% w/w. So there was no significant change in the mucilage content of the formulation during the study period.

10. Weight variation:

The samples of Urito capsules were tested for weight variation during the period of stability studies. The test was performed as per USP standards. It was found that the weights of the capsules of the polyherbal formulation, Urito were within the limits of 90% and 110% of the average weight of the capsules, throughout the period of study. Thus it was concluded that the capsules were of uniform weight throughout the period of stability studies.

11. Disintegration test:

Disintegration time of a capsule is the time required for the capsule along with its contents, to disintegrate completely. It should not take more time to disintegrate and the time should not vary much during the stability studies. The test was performed according to USP standards and the time taken to disintegrate was noted. The results were shown graphically in Figure 9 as time taken to disintegrate versus number of days.

Table 9. Disintegration time of Urito capsules

Number of days	Disintegration time (seconds)
0	375
15	375
30	375
45	375
60	375
75	380
90	380
105	385

Figure 9. - Disintegration time of Urito capsules

The disintegration time of Urito capsules did not vary much throughout the period of study and was found to be almost same except for a slight increase of 5 sec by the end of the study. The standard arrived was Not More Than 400 seconds and the results showed that all the values were within the standard limit arrived.

From the above study it was found that the polyherbal capsules of urito are stable under accelerated condition. Thus, the quality control profile of our herbal product has been taken a step ahead.

ACKNOWLEDGEMENT:

I would like to thank Faculty of Pharmacy, Sri Ramachandra University, Porur, Chennai for allowing me to carry out this work. Also, I thanks Rumi Herbals Pvt. Ltd., Mugappair, Chennai for providing the samples of Urito to perform this work.

REFERENCES:

1) Sheetal Verma, S.P. Singh, Current and future status of herbal medicines Veterinary World, 2009, 1(11), 347-350

2) M.S.Wani, Herbal Medicine and Its Standardization, Latest Reviews , 2007, 5(6).

3) V. Kalaiselvan et al., Quality assessment of different marketed brands of Dasamoolaristam, an Ayurvedic formulation, Int J Ayurveda Res., 2010, 1(1) 10–13

4) Eng Shi Ong, Extraction methods and chemical standardization of botanicals and herbal preparationspurchase this article., Journal of Chromatography B, 2004, 812 (1-2) 23-33.

5) Anonymous, 1991. Guidelines for the Assessment of Herbal Medicines, Document No.WHO/TRM/91, 4, World Health Organization, Geneva.

6) Phillipson, J.D, Ethnopharmacology and Western Medicine. J. Ethnopharmacol., 1989, 25, 61-72

7) “Quality Assurance of Pharmaceuticals - A Compendium of Guidelines and Related Materials,” Volume 1, World Health Organization, Geneva, 1997. (NLM Classification: QV 34)

8) “WHO expert committee on specifications for pharmaceutical preparations,” Forty-third report. World Health Organization, Geneva, 2009. (WHO technical report series, No. 953)

9) Anonymous, Indian pharmacopoeia, New Delhi (India) CSIR, Vol II, 1996, A-53, 54, 89.

10) “Quality Control Methods for Medicinal Plant Materials,” World Health Organization, Geneva, 1992. (NLM Classification: QV 766)

11) “Good manufacturing practices: supplementary guidelines for the manufacture of herbal medicinal products,” World Health Organization, Geneva, 1996. (WHO Technical Report Series, No.863) Annex 8.

12) National Pharmaceutical Control Bureau, Ministry of Health, Malaysia: Guidelines for stability studies of Drug products, 1984.

Received on 19.02.2011

Accepted on 28.02.2011

Research Journal of Pharmacognosy and Phytochemistry. 3(3): May- June 2011, 128-133