AN ORAL DRUG DELIVERY SYSTEM
The present invention relates to an improved drug
delivery system, and, in particular, to an improved drug
delivery system for. the oral administration of lipophilic
poorly water-soluble drugs in immediate release dosage-
forms ,
The bioavailability of lipophilic, poorly water-soliible
drugs when administered orally in solid dosage forms (such
as tablets) is notoriously low and variable. This has led
to the development of dosage forms in which the drug is pre-
dissolved in either a lipid vehicle or a mixture of "a lipid
vehicle and a surfactant or a ternary mixture of a lipid
vehicle, a surfactant and a co-sol vent. Such compositions
provide an increeLsed bioavailability of the drug but only at
the cost of increased complexity and, in most cases, the
need to include very high levels (30% or greater) of
surfactant or emulsifier.
Existing lipid-based delivery vehicles for lipophilic
drugs include the simple .solution of the drug in a
lipophilic vehicle, self-emulsifying oil systems, micro-
emulsions and liposomes- The properties and application
characteristics of lipophilic drug delivery vehicles have
been the subject of numerous reviews - for example,
Humberstone & Charman (1997) Advanced Drug Delivery Review
V.25, 103-128 and O'Driscoll (2002) European Journal of
Pharmaceutical Science v.15, 405-415.

Lipophilic Solution.
A number of drugs have an appreciable solubility in
lipophilic oils (especially triacyl glycerides) alone. It
is therefore possible to administer the drug as a simple
solution in a capsule and obtain satisfactory absorption and
bioavailability. However, the dispersion kinetics of such a
formulation cannot be expected to be as rapid as would be
obseirved for a pre-dispersed system- The slow dispersion of
the formulation is a major limitation of this dosage form.
Self-emulsifying Oil Systems
These are sometimes referred to as SEDDS (*self-
emulsifying drug delivery systems') and comprise a mixture
of an oil and a • surfactajit that spontaneously forms an oil-
in-water emulsion when diluted with water. The solubility
of the drug is typically enhanced by the presence of the
surfactant - which is usually present in concentrations as
high as or greater than 30%. Co-solvents such as ethanol,
propylene glycol and polyethylene glycol are sometimes added
in order to increase the solubility of the drug. This
dosage form is a lipophilic, isotropic liquid which may be
filled into capsules and which, when liberated from the
capsule in the gastrointestinal tract, forms a dispersion of
small drug-containing oil/surfactant droplets which spread
rapidly. The main disadvantage of SEDDS relates to the
presence of the large amounts of surfactant, which, apart
from potentially having a harmful effect on the intestinal
wall, adds to the cost and complexity of the formulation.
Examples of such compositions are disclosed in US Patents
Nos. 6436430 and 6284268.

Microemulsion preconcentrates
These are essentially similar to SEDDS and comprise
isotropic mixtures of drug, lipid, surfactant and (if
required) co-solvent and co-surfactant. As with the self-
emulsifying drug delivery systems, on addition to an aqueous
medium these systems disperse to form liquid/liquid
dispersions. The primary difference between microemulsion
preconcentrates and SEDDS is the nature of the dispersion
formed, where the microemulsion preconcentrates disperse to
form thermodynamically stable microemulsions.
Microemulsions have been shown to enhance the
bioavailability of lipophilic drugs but suffer from the same
niajor disadvantage as for SEDDS - the very high level of
surfactant needed for their formation. Examples of such
compositions are disclosed in US Patents Nos. 5993858 and
63 09665...
Liposome^,
Liposomes consist of ordered layers of phospholipid
molecules which encapsulate a central aqueous lumen. The
possibility exists for lipophilic drugs to be solublised
within the phospholipid layers. The drug carrying
capabilities of liposomes are sufficient for use in
parenteral formulations, but are not particularly suitable
for use in oral dosage forms. Furthermore, liposomes are
unstable and expensive to produce and therefore have limited
potential for the delivery of lipophilic drugs. Examples of
such compositions are disclosed in US Patents Nos. 4746516
and 6090407.
Other dosage forms include the conversion of
microemulsions into solid or semisolid nano particles and
the use of polyaphrons. US Patent No. 4999198 discloses a
polyaphron comprising a continuous phase and a disperse
phase in which a drug, specifically scopolamine, is carried.
The patent describes the slow release of the drug from the
polyaphron into a medium with which the polyaphron is in
contact and in particular the transdermal delivery of drugs.
The invention described here is different from that
previously described in US Patent No. 4999198. No reference
has previously been given to the use of such polyaphrons as
an oral delivery system which is compatible with hard or
soft gelatin capsules. No specific water to lipid phase
ratio is given in the previous patent. Furthermore,
scopolamine is the only drug specifically mentioned.
The disadvantages of the oral formulations for the
delivery of lipophilic poorly water-soluble drugs have been
discussed above. None of the current formulations is
particularly satisfactory.
We have now developed a readily dispersible two-phase
system for the oral delivery of poorly water-soluble drugs
which has a low water content (less than 10% w/w water) and
therefore gives the system a good compatibility with
gelatin, thereby enabling the drug formulation to be
encapsulated in hard or soft gelatin capsules. Furthermore,
the two-phase system is simple to produce and requires the
use of only a limited amount of potentially expensive and
harmful surfactants.
Accordingly, the present invention provides an oral
drug delivery system which comprises a biliquid foam
comprising
from 1 to 20% by weight of a continuous hydrophilic
phase,
from 70 to 98% by weight of a pharmaceutically
acceptable oil which forms a discontinuous phase, the
said pharmaceutically acceptable oil having dissolved
or dispersed therein a poorly water-soluble drug in an
amount of from 0.1 to 2 0% by weight
and the biliguid foam including therein from 0.5 to lO?--,
preferably 0,5 to 5%, by weight of a surfactant to enable
the formation of a stable biliguid foam, all percentages
being based upon the total weight of the formulation.
By the term "biliquid foam" which is used herein, which
is also referred to in the art as a "polyaphron", is meant a
non-isotropic dispersion of a non-polar liquid suspended in
a continuous polar phase.
By the term "poorly water-soluble drug" as used herein
is meant a drug which will dissolve in water in an amount of
less than 1% by weight. The discontinuous phase contains
the drug in an amount of 0.1 to 20% by weight, for example 1
to 10% by weight or 2 to 7% by weight. It is also possible
for some drug to be present in the continuous hydrophilic
phase, particularly if a cosolvent such as a polyethylene
glycol is used.
The pharmaceutically acceptable oil which is used in
the present invention is preferably a mono-, di- or
triglyceride, or a mixture thereof. In particular the
mono-, di- or triglycerides are preferably the glycerol
esters of fatty acids containing from 6 to 22 carbon atoms.

Examples of oils which may be used in the present
invention include almond oil, babassu oil, blackcurrant seed
oil, borage oil, canola oil, castor oil, coconut oil, cod
liver oil, corn oil^ cottonseed oil, evening primrose oil,
fish oil, grapeseed, oil, mustard seed oil, olive oil, palm
kernel oil,, palm oil, peanut oil, rapeseed oil, safflower
oil, sesame oil, shark liver oil, soybean oil, sunflower
oil, walnut oil, wheat germ oil, hydrogenated castor oil,
hydrogenated coconut oil, hydrogenated cottonseed oil,
hydrogenated palm oil, hydrogenated soybean oil, partially
hydrogenated soybean oil, hydrogenated vegetable oil,
modified triglycerides, caprylic/capric glycerides,
fractionated triglycerides, glyceryl tricaprate, glyceryl
tricaproate, glyceryl tricaprylate, glyceryl
tricaprylate/caprate, glyceryl tricaprylate/caprate,
glyceryl tricaprylate/caprate/laurate, glyceryl
tricaprylate/caprate/linoleate, glyceryl
tricaprylate/caprate/stearate, glyceryl trilaurate, glyceryl
trilinoleate, glyceryl trilinolenate, glyceryl trioleate,
glyceryl tritmdecanoate, linoleic glycerides, saturated
polyglycolized glycerides, synthetic medium chain
triglyceride containing primarily C8-C12 fatty acid chains,
medium chain triglycerides, long chain triglycerides,
modified triglycerides, fractionated triglycerides, and
mixtures thereof.
Examples of mono and diglycerides which may be used in
the present invention include propylene glycol mono and
diesters having from 15 to 40 carbon atoms, including
hydrolysed coconut oils (e.g. Capmul MCM), hydrolysed corn
oil (e.g. Maisine 35-1).
The monoglycerides and diglycerides are mono- or di
saturated fatty acid esters of glycerol having eight to
sixteen carbon chain length.
Essential oils may also be used in the present
invention.
The surfactant used in the present invention may be
incorporated into either or both phases of the biliquid
foam. The surfactant used in the present invention is
preferably an alkyl polyglycol ether, an alkyl polyglycol
ester, an ethoxylated alcohol, a polyoxyethylene sorbitan
fatty acid ester, a polyoxyethylene fatty acid ester, an
ionic or non-ionic surfactant, a hydrogenated castor
oil/polyoxyethylene glycol adducts containing from 25 to 6 0
ethoxy groups a castor oil/polyoxyethylene glycol adduct
containing from 25 to 45 ethoxy groups, a sorbitan fatty
acid ester (for example Span 2 0 or Span 80), a block
copolymer of ethylene oxide and propylene oxide (for example
Pluronic L121 or Pluronic F68), or a mixture thereof. The
surfactant may be used in an amount of from 0.5 to 10% by
weight of the biliquid foam but preferably is used in an
amount of from 0.5 to 5%, even more preferably 1 to 2%, by
weight of the biliquid foam.
A co-emulsifier may be used in the formation of the
biliquid foams in an amount sufficient to complete the
solubilization of the poorly water-soluble drug. A suitable
co-emulsifier is a phosphoglyceride, a phospholipid, for
example lecithin, or a free fatty acid that is liquid at
room temperature, for example iso-stearic acid, oleic acid,
linoelic acid or linolenic acid.
The continuous hydrophilic phase of the biliguid foam
may comprise water or may comprise a.n aqueous phase which
includes therein an additional component to reduce the
affinity of, the aqueous phase for a capsule forming material
such as gelatin. The additional component may be a salt
such as sodium chloride, or a co-solvent such as an
aliphatic alcohol, polyethylene glycol, propylene glycol or
glycerol, or mixtures thereof or a gelling agent such as
alginate gums or their salts, guar gum, locust bean gum,
xanthan, gum, gum acacia, gelatin, hydirbxymethyl-cellulose
hydroxyethylcellulose, hydroxyprppyl-cellulose,
carboxymethylcellulose or its salts, bentbnites, magnesium
aluminium silicates,.; "Carbomers" (salts of cross-linked
polymers ,of acrylic acid), or glycesryl pblymethacrylates or
their idispersiohs in glycols, or a polyvinylpyirrolidone
polymer.or a water-dispersible; copolymer thereof, or any
appropriate mixture of any of these polymers and gums.
Alternatively, the hydrophilic phase may be non-aqueous
and may be, for. example, an aliphatic alcohol, polyethylene
glycol, propylene glycol or glycerol, or mixtures thereof.
Water-soluble inorganic salts may be added to improve
the stability of the biliquid foams, such as those formed
from monovalent cations such as Na+, K+ or NH4+, divalent
cations such as Ca++ or Mg++ or trivalent cations such as
Al+++. Water solxoble polysaccharides such as sucrose,
glucose or fructose may alsb be added to improve stability.
Poorly water-soluble drugs which may be used in the
present invention include the following:
Analgesics and anti-inflammatory agents: aloxiprin,
auranofin, azapropazone, benorylate, diflunisal, etodolac,
fenbufen, fenoprofen calcium, flurbiprofen, ibuprofen,
indomethacin, ketoprofen, mefenamic acid, nabumetone,
naproxen, oxyphenbutazone, phenylbutazone, piroxicam,
sulindac.
Anthelmintics: albendazole, bephenium
hydroxynaphthoate, dichlorophen, ivermectin, mebendazole,
oxfendazole, oxantel embonate, praziquantel, pyrantel
embonate, thiabendazole.
Anti-arrhythmic agents: amiodarone HCl, disopyramide,
quinidine sulphate.
Anti-bacterial agents: benethamine penicillin,
cinoxacin, ciprofloxacin HCl, clarithromycin, clofazimine,
cloxacillin, doxycycline, erythromycin, ethionamide,
imipenem, nalidixic acid, nitrofurantoin, rifampicin,
spiramycin, sulphabenzamide, sulphadoxine, sulphamerazine,
sulphacetamide, sulphadiazine, sulphafurazole,
sulphamethoxazole, sulphapyridine, tetracycline,
trimethoprim.
Anti-coagulants: dicoumarol, dipyridamole, nicoumalone,
phenindione.
Anti-depressants: amoxapine, maprotiline HCl,
trimipramine maleate.
Anti-diabetics: acetohexamide, chlorpropamide,
glibenclamide, gliclazide, glipizide, tolazamide,
tolbutamide.
Anti-epileptics: becleunide, carbamazepine, clonazepam,
ethotoin, methoin, methsuximide, methylphenobarbitone,
phenacemide, phenobarbitone, phenytoin, phensuxiimide,
primidone, sulthiame, valproic acid.
Anti-fungal agents: amphotericin, butoconazole nitrate,
clotrimazole, econazole nitrate, fluconazole, griseofulvin,
itraconazole, ketoconazole, miconazole, natamycin, nystatin,
sulconazole nitrate, terbinafine HCl, terconazole,
tioconazole, undecenoic acid.
Anti-gout agents: allopurinol, probenecid, sulphin-
pyrazone.
Anti-hypertensive agents: amlodipine, diazo:icide,
felodipine, isradipine, minoxidil, nicardipine HCl,
nifedipine, ndLmodipine, prazosin HCl, reserpine.
Anti-malarials: amodiaquine, chloroquine, halofantrine
HCl, mefloquine HCl, proguanil HCl, pyrimethamine, quinine
sulphate.
Anti-migraine agents: dihydroergotamine mesylate,
ergotamine tartrate, methysergide maleate, pizotifen
maleate.
Anti-muscarinic agents: atropine, benzhexol HCl,
biperiden, hyoscyamine, mepenzolate bromide, tropicamide.
Anti-neoplastic agents and Immunosuppressants:
aminoglutethimide, azathioprine, busulphan, chlorambucil,
cyclosporin, dacarbazine, etoposide, lomustine, melphalan,
mercaptopurine, methotrexate, mitomycin, mitotane, tamoxifen
citrate, testolactone.
Anti-protazoal agents: clioquinol,
diiodohydroxyquinoline, diloxanide furoate, dinitolmide,
furzolidone, metronidazole, nitrofurazone, tinidazole.
Anti-thyroid agents: carbimazole, propylthiouracil.
Anxiolytic, sedatives, hypnotics and neuroleptics:
alprazolam, amylobarbitone, barbitone, bromazepam,
bromperidol, brotizolam, butobarbitone, carbromal,
chlordiazepoxide, chlormethiazole, chlorpromazine, clobazam,
clozapine, diazepam, droperidol, ethinamate, fluanisone,
flunitrazepam, fluopromazine, flupenthixol decanoate,
fluphenazine decanoate, flurazepam, haloperidol, lorazepam,
lormetazepam, medazepam, meprobamate, methaqualone,
midazolam, nitrazepam, oxazepam, pentobarbitone,
perphenazine pimozide, prochlorperazine, sulpiride,
temazepam, thioridazine, triazolam, zopiclone.
p-Blockers: nadolol, pindolol.
Cardiac Inotropic agents: digitoxin, digoxin,
lanatoside C, medigoxin.
Corticosteroids: beclomethasone, betamethasone,
budesonide, cortisone acetate, desoxymethasone,
dexamethasone, fludrocortisone acetate, flunisolide,
flucortolone, fluticasone propionate, hydrocortisone,
methylprednisolone, prednisolone, prednisone, triamcinolone.
Diuretics: acetazolamide, amiloride, bendrofluazide,
bumetanide, chlorothiazide, chlorthalidone, ethacrynic acid,
frusemide, metolazone, spironolactone, triamterene.
Anti-parkinsonian agents: bromocriptine mesylate.
Gastro-intestinal agents: bisacodyl, cimetidine,
cisapride, diphenoxylate HCl, domperidone, famotidine,
loperamide, mesalazine, omeprazole, sulphasalazine.
Histamine H,-Receptor Antagonists: astemizole,
cinnarizine, cyclizine, cyproheptadine HCl, dimenhydrinate,
meclozine HCl, oxatomide, terfenadine.
Lipid regulating agents: bezafibrate, clofibrate,
fenofibrate, gemfibrozil, probucol.
Nitrates and other anti-anginal agents: amyl nitrate,
glyceryl trinitrate, isosorbide dinitrate, pentaerythritol
tetranitrate.
Nutritional agents: betacarotene, vitamin A, vitamin
B2, vitamin D, vitamin E, vitamin K.
Opioid analgesics: codeine, dextropropyoxyphene,
diamorphine, dihydrocodeine, meptazinol, morphine,
pentazocine.
Sex hormones: clomiphene citrate, danazol, ethinyl
estradiol, medroxyprogesterone acetate, mestranol,
methyltestosterone, norethisterone, norgestrel, estradiol,
conjugated oestrogens, progesterone, stanozolol, stibestrol,
testosterone, tibolone.
Stimulants: dexamphetamine, dexfenfluramine, mazindol.
Pharmaceutically acceptable salts, isomers and
derivatives thereof may be substituted for these drugs.
Mixtures of lipophilic drugs may be used v\?here
therapeutically effective.
The discontinuous phase of the present invention
comprises 70 to 98% by weight, preferably from 80 to 96% by
weight, more preferably from 90 to 95% by weight of the
biliquid foam. The continuous hydrophilic phase comprises
from 1 to 20% by weight, preferably from 2 to 10% by weight
of the biliquid foam.
The oral drug delivery systems of the present invention
are preferably presented in a unit dosage form". The
preferred unit dosage form comprises capsules filled with
the biliquid foam, for example hard or soft gelatin
capsules. The use of the gelatin capsules is made possible
by the low water content of the biliquid foam which ensures
good compatibility both with the hard and soft gelatin
capsules and the optional incorporation into the aqueous
phase of an additional component which reduces the affinity
of the aqueous phase for the capsule material, This is an
advantage over the currently available lipid dispersions and
provides a better bioavailability of the drug as compared to
tablets.
Each unit dosage form will comprise, for example, from
O.Smg to 1000mg, preferably 0.5 to 200mg of the drug, for
example in up to a 1000mg, preferably 100mg, dosage form.
The biliquid foams of the drug delivery systems may
also be presented as dilutable concentrates which are
infinitely dilutable in a co-solvent such as water or a
water compatible aliphatic alcohol, polyethylene glycol,
propylene glycol or glycerol, or mixtures thereof. Dilution
of the biliquid foam preparations is possible and they may
be incorporated into a drink, syrup or linctus.
The biliquid foam compositions of the present invention
may also contain other additives such as preservatives or
antimicrobial agents(for instance to prevent microbiological
spoilage). These additives may be included in the non-polar
liquid or the continuous phase.

It will be understood that the inclusion of these
additives will be at the levels and with the type of
materials which are found to be effective and useful. Care
needs to be taken in the choice and amount of these
additives to prevent compromise to the other performance
advantages of the present invention.
Methods of producing biliguid foams are described in
US-A-4486333 involving the preliminary formation of a gas
foam in order to provide a sufficiently large surface area
on which' the biliguid foam can subsequently be formed. It
has been found that the prior formation of a gas foam is not
required to manufacture a stable biliquid foam, provided
that a suitable stirxing mechanism is provided in the
manufacturing vessel.
Such an apparatus comprises a tank provided with a
stirrer in which the stirrer blade breaks the interface
between the liquid and air. A delivery device is provided
through which the oil phase (non-polar liquid), which will
comprise the internal phase of the dispersion is delivered
to the tank. The design of the delivery device is such that
the rate of addition of the internal phase fluid can be
controlled and varied during the production process. A
feature of the production process is that the internal (oil)
phase is added to the stirred aqueous phase slowly at first
until sufficient droplets have been formed to constitute a
large surface area for the more rapid formation of new
droplets. At this point, the rate of addition of the oil
phase may be increased.
The production process consists of the following steps:
1. The addition of one or more chosen surfactaiats to
one or other or both phases (as previouslv determined by
experiment]
2. The charging:Of the aqueous, phase into the bottom
of a process vessel»
3. The incorporation of the .stirrer into the vessel
so that it stirs the surface of the aqueous phase.
4- Adjustment of the stirrer speed to a previously-
determined level.
5. The slow addition of the internal (oil) phase
containing the poorly water-soliible idrug dissolved or
dispersed therein whilst. continuing to stir at the
prescribed speed.
6. The speeding.up. of the rate of addition of the oil
phase once a prescribed amount (usually between 5% and 10%
of the total amount to be added) has been added.
The stirring rate and the rate of addition of the oil
phase are variables, the values of which;depend upon the
detailed design of the manufacturing plant (in particular,
the ratio of tank diameter to impeller diameter), the
physico-chemical properties of the -oil phase and the nature
and concentrations of the. chosen surfactants. These can all
be pre-determined by laboratory or pilot plant experiment.
It will be understood by those skilled in the art that
other manufacturing methods may be used, as appropriate.
Although the stability of the biliquid foams is
generally good, they may be stabilised by the add,ition of an
aqueous gel and, accordingly, the present invention includes
within its scope a stable dispersion which comprises from 1
to 80% by weight of a biliguid foam and from 20 to 99% by-
weight of an aqueous gel.
The aqueous gel will preferably be formed from a
colloidal polymer or gum suspended in water, at a
concentration of from 0.05 to 20% by weight, more preferably
from 0.2 to 1% by weight. Suitable polymers or gums are,
for example, alginate gums or their salts, guar gum, locust
bean gum, xanthan gum, gum' acacia, gelatin,
hydroxymethylcellulose hydroxyethylcellulose,
hydroxypropylcellulose, carboxymethylcellulose or its salts,
bentonites, magnesium aluminium silicates, "Carbomers"
(salts of cross-linked polymers of acrylic acid), or
glyceryl polymethacrylates or their dispersions in glycols,
or any appropriate mixture of any of these polymers and
gums.
The present invention will be further described
with reference to the following examples:
Biliquid Foam Preparation
A suitable vessel was charged with the aqueous phase of
the biliquid foam. The drug was dissolved in the oil phase.
The oil phase containing the drug was then added at a
constant rate with stirring, using a sweep stirrer or an
orbital mixer. After completion of the oil addition, the
stirring was continued until the size of the oil droplets
became stable or reached a desired size.
Example 16
In order to demonstrate the advantages of the present
invention a test was carried out to compare formulations of
the present, invention with a tablet.
A commercial formulation Halfan® (Batch no. 558, SmithKline
& French, UK) was tested. Analysis showed that it contained
24 8 mg Halofantrine. The bioavailability was tested in
fasted male beagle dogs and compared with that obtained
using the formulation of Example 7 (LCT BLF) and the
formulation of Example 7 except that the soybean oil is
replaced with caprylic/capric triglycerides (MCT BLF). The
dogs, weighing from 12 to 19 kg, were dosed in a randomised
crossover study. The dogs were fasted for 21 hours prior to
dosing. B100d samples were collected at -15 min (pre-close
blank) and subsequently at 15, 30, 60 and 90 mins and at 2,
3, 4, 6, 8, 10, 24, 32, 48 and 72 hours poet-dosing. The
following results were obtained:
Cmax = concentration maximum measured in b100d after oral
administration.
Tmax = time from administration taken to reach Cmax.
AUG = Area under curve: a measure of the total amount
appearing in the.b100d over time.
Relative bioavailability compared with tablets(%) = Relative
bioavailability, compared to that from the tablet, expressed
as a percentage.
WE CLAIM:
1. An oral drug delivery system which comprises a biliquid
foam comprising:
from 1 to 20% by weight of a continuous
hydrophilic phase,
from 70 to 98% by weight of a pharmaceutically
acceptable oil which forms a discontinuous phase, the
said pharmaceutically acceptable oil having dissolved
or dispersed therein a poorly water-soluble drug in an
amount of from 0.1 to 20% by weight,
wherein the poorly water-soluble drug is a drug which
will dissolve in water in an amount of less than 1% by
weight,
and the biliquid foam including therein from 0.5 to 10% by
weight of a surfactant to enable the formation of a stable
biliquid foam, all percentages being based upon the total
weight of the formulation.
2. An oral drug delivery system as claimed in claim 1
wherein the continuous hydrophilic phase is an aqueous
phase.
3. An oral drug delivery system as claimed in claim 2
wherein the aqueous phase is water.
4. An oral drug delivery system as claimed in claim 2
wherein the aqueous phase incorporates a salt or a co-
solvent therein.
5. An oral drug delivery system as claimed in claim 1
wherein the continuous hydrophilic phase is a non-aqueous
solvent.

An oral drug delivery system which comprises a biliquid foam comprising: from 1 to 20% by weight of a continuous hydrophilic phase, from 70 to 98% by weight of a pharmaceutically acceptable oil which forms a discontinuous phase, the said pharmaceutically acceptable oil having dissolved or dispersed therein a poorly water-soluble drag in an amount of from 0.1 to 20% by weight and the biliquid foam including therein from 0.5 to 10% by weight of a surfactant to enable the formation of a stable
biliquid foam, all percentages being based upon the total weight of the formulation.