title: Determination of required hydrophilic-lipophilic balance of citronella oil and development of stable cream formulation.
abstract: BACKGROUND
  Citronella oil is reported to have excellent mosquito-repellent activity. To develop a stable cream formulation (emulsion), its hydrophilic-lipophilic balance (HLB) value is important.
  
  
  OBJECTIVE
  To determine required hydrophilic-lipophilic balance (rHLB) value of citronella oil and to develop stable cream formulation.
  
  
  METHODS
  Emulsions of citronella oil were prepared by phase inversion temperature technique using water, Tween 80 and Span 80. A first series of 11 emulsions with HLB values ranging from 5.0 to 15.0 and a second series of eight emulsions with smaller interval in HLB values from 11.0 to 13.8 were prepared. Emulsions were evaluated for creaming index, droplet size and turbidity to determine rHLB. Utilizing determined rHLB, citronella oil cream was formulated and evaluated for different texture parameters. rHLB of light liquid paraffin was also determined for validation of methodology.
  
  
  RESULTS
  rHLB of light liquid paraffin and citronella oil was determined to be 11.80 and 12.60, respectively. Stable citronella oil cream was developed with 10% emulsifier blend. Texture parameters were found to be consistent over the entire storage period.
  
  
  CONCLUSIONS
  Creaming index, droplet diameter, percent increase in droplet diameter and turbidity are the established parameters to determine rHLB and to develop stable emulsion. Emulsions with optimum emulsifier concentration resulted in less percentage creaming index, smallest droplet, less percentage increase in droplet diameter and highest turbidity. Texture properties evaluation ensures the stability of the developed cream.
  
  
  CONCLUSIONS
  rHLB value of citronella oil was found 12.6 and a stable cream was formulated utilizing determined rHLB.
authors.affiliation: Herbal Medicinal Product Department, Central Institute of Medicinal and Aromatic Plants Council of Scientific and Industrial Research, P.O. CIMAP, Lucknow, UP, India 226015.
authors.forename: Jaya Gopal
authors.initials: JG
authors.lastname: Meher
authors.forename: Narayan Prasad
authors.initials: NP
authors.lastname: Yadav
authors.forename: Jagat Jyoti
authors.initials: JJ
authors.lastname: Sahu
authors.forename: Priyam
authors.initials: P
authors.lastname: Sinha
mesh_terms: D000818:Animals; D055598:Chemical Phenomena; D002626:Chemistry, Pharmaceutical; D009033:Culicidae; D031743:Cymbopogon / Q000737:chemistry*; D003879:Dermatologic Agents / Q000008:administration & dosage / Q000737:chemistry*; D004355:Drug Stability; D004655:Emulsions; D005079:Excipients / Q000737:chemistry; D006601:Hexoses / Q000737:chemistry; D057927:Hydrophobic and Hydrophilic Interactions; D007302:Insect Repellents / Q000008:administration & dosage / Q000737:chemistry*; D009822:Oils, Volatile / Q000008:administration & dosage / Q000737:chemistry*; D018515:Plant Leaves / Q000737:chemistry; D010938:Plant Oils / Q000008:administration & dosage / Q000737:chemistry; D018547:Plant Stems / Q000737:chemistry; D011136:Polysorbates / Q000737:chemistry; D063465:Skin Cream / Q000008:administration & dosage / Q000737:chemistry; D013501:Surface-Active Agents / Q000737:chemistry; D044366:Transition Temperature
chemical_list: D003879:Dermatologic Agents; D004655:Emulsions; D005079:Excipients; D006601:Hexoses; D007302:Insect Repellents; D009822:Oils, Volatile; D010938:Plant Oils; D011136:Polysorbates; D013501:Surface-Active Agents; C018665:sorbitan monooleate; C076730:citronella oil