This document discusses the calculation of an effervescent formula for vitamin C tablets. It begins by providing the formula for a 1.5g effervescent tablet, which includes 500mg of vitamin C. It then calculates the formula based on the tablet weight, dividing it into inner and outer phases. The weights of the acid and base components are calculated based on their molecular weights and equivalents in the reaction equations provided. Ratios of citric acid, tartaric acid and sodium bicarbonate are determined for an effervescent granule example based on these calculations.

1. PERHITUNGAN FORMULASI
EFFERVECENT
Antonius Padua Ratu, M.Farm., Apt.
STTIF Bogor 2020

2. PERHITUNGAN FORMULA TABLET VITAMIN C
Satu tablet effervescent dibuat dengan bobot 1,5 gram.
Formula untuk 1 buah tablet effervescent :
Vitamin C 500 mg
Pyridoxine 20 mg
PVP 3% 45 mg
Sukrosa 15% 225 mg
Asam sitrat monohidrat qs
Asam tartrat qs
Natrium bikarbonat qs
PEG 8000 30 mg

3. PERHITUNGAN FORMULA
Bobot tablet effervescent 1500 mg
• Fasa dalam (98%)
Bobot = 98/100 x 1500 mg = 1470 mg
Fasa dalam terdiri dari
– zat aktif
– asam
– basa
– pengikat
– pengisi
• Fasa luar (2%)
Bobot = 2/100 x 1500 mg = 30 mg
Fasa luar terdiri dari pelincir
• Bobot asam dan basa = fasa dalam – (zat aktif + pengikat + pengisi)
= 1470 mg – ( 520 + 45 + 225 ) mg
= 680 mg

4. BOBOT MOLEKUL DAN BOBOT EKIVALEN
Asam sitrat monohidrat:BM = 210,13
C6H8O7.H2O Bilangan ekivalen = 3 (jumlah gugus COOH)
Bobot ekivalen = 210,13/3 = 70,04
Asam tartrat: BM = 150,09
C4H6O6 Bilangan ekivalen = 2 (jumlah gugus COOH)
Bobot ekivalen = 150,09/2 = 75,05
Natrium bikarbonat: BM = 84,01
NaHCO3 Bilangan ekivalen = 1 (jumlah kation Na+ atau
Anion HCO3
-)
Bobot ekivalen = 84,01/1 = 84,01

5. PERSAMAAN REAKSI ASAM DAN BASA
Supaya reaksi sempurna antara asam sitrat dengan natrium
bikarbonat dan asam tartrat dengan natrium bikarbonat maka :
3 NaHCO3 + C6H8O7.H2O → 4 H2O + 3 CO2 + Na3C6H5O7
84,01 70,04
2 NaHCO3 + C4H6O6 → 2 H2O + 2 CO2 + Na2C4H4O6
84,01 75,05
(84, 01 mol ekivalen +70,04 mol ekivalen) + (84,01 mol ekivalen + 75,05 mol ekivalen)  680 mg
313,11 mol ekivalen  680 mg

6. PERHITUNGAN ASAM DAN BASA
Asam sitrat monohidrat
= ( 70,04 / 313,11 ) x 680 = 152,10 mg
Asam tartrat
= ( 75,05 / 313,11 ) x 680 = 162,99 mg
Natrium bikarbonat
= (( 84,01+84,01 ) / 313,11 ) x 680= 364,91 mg

7. Effervescent Granules
Granules are dosage forms that consist of particles ranging from about 4
to 10 mesh in size (4.76 to 2.00 mm), formed by moistening blended
powders and passing through a screen or a special granulator.
These moist granules are either air- or oven-dried. A special form of
granules can be used to provide a pleasant vehicle for selected drug
products, especially those with a bitter or salty taste. This special
formulation, an effervescent granule, may consist of mixtures of citric acid
and/or tartaric acid and/or sodium biphosphate combined with sodium
bicarbonate.
EXAMPLE
Rx
Active drug 500 mg/5 g tsp
in effervescent granule qs 120 g
Sig: Dissolve 1 teaspoonful in one-half glass of cool water and drink.
Repeat this every 8 h.

8. Calculate
• Sig: Dissolve 1 teaspoonful in one-half glass of cool water and
drink. Repeat this every 8 h.
• It is desired to dispense this as a granule, so that the patient will
measure out a teaspoonful (5 g) dose, mix, and administer.
• Since each dose weighs 5 g and the prescription consists of 120
g, there are 24 doses. Each dose contains 0.5 g of the active
drug, which comes to 12 g of the active drug for the entire
prescription.
• This requires 120 g − 12 g = 108 g of effervescent vehicle.
• A good effervescent blend consists of both citric acid and tartaric
acid (1:2 ratio), since the former is rather sticky and the latter
produces a chalky, friable granule.
• It is necessary to calculate the amount of each ingredient
required to prepare 108 g of the granulation.

9. Acid and Base
CITRIC ACID
3NaHCO3 + C6H8O7.H2O → 4 H2O + 3 CO2 + Na3C6H5O7
3 × 84 210
Citric acid 1 g (MW = 210) of citric acid reacts with 1.2 g (MW = 84) of sodium
bicarbonate as obtained from the following:
1 𝑔
210
=
𝑋
3 𝑥 84
𝑋 = 1,2 𝑔
TARTARIC ACID
2 NaHCO3 + C4H6O6 → 2 H2O + 2CO2 + Na2C4H4O6
2 × 84 150
Since it is desired to use a 1:2 ratio of citric acid to tartaric acid, 2 g (MW = 150) of
tartaric acid reacts with sodium 2.24 g of bicarbonate according to the following
calculation:
2 𝑔
150
=
𝑋
2 𝑥 84
𝑋 = 2,24 𝑔

10. Ratio adn Quantity
• Therefore, the ratio of the effervescent ingredients is
1:2:3.4 for the citric acid:tartaric acid:sodium bicarbonate.
• Since the prescription requires 108 g of the effervescent
mix, the quantity of each ingredient can be calculated as
follows:
1 + 2 + 3.4 = 6.4
1/6.4 × 108 g = 16.875 g of citric acid
2/6.4 × 108 g = 33.750 g of tartaric acid
3.4/6.4 × 108 g = 57.375 g of sodium Bicarbonate
Total = 108 g
• The prescription will require 12 g of the active drug and
108 g of this effervescent vehicle.

11. Terima kasih