Spill resistant pharmaceutical compositions in semi-solid form

Details Spill resistant pharmaceutical compositions in semi-solid form Spill resistant pharmaceutical compositions in semi-solid form

2000-04-13

2002-06-04

Page, Thurman K. (Department: 1615)

Drug, bio-affecting and body treating compositions

Preparations characterized by special physical form

C424S401000, C222S192000, C222S212000, C222S153060, C141S018000, C141S114000, C141S115000

Reexamination Certificate

active

06399079

ABSTRACT:

BACKGROUND OF THE INVENTION
The invention relates to compositions for administering pharmaceuticals orally without spilling. More specifically, the invention relates to vehicles and devices for delivering a variety of pharmaceutical products.
Syrups, elixirs, solutions, and suspensions are traditional dosage forms for oral medication. These liquid formulations are typically measured by pouring into a spoon, but this approach has the great drawback of spillage. The risk of spillage can cause people to underfill the spoon, leading to inaccurate dosage. With elderly people, children, and the infirm, difficulty in filling a spoon with a liquid and bringing it to the mouth can be a serious impediment to administering the medicine. Solid formulations such as pills, tablets, and capsules are also difficult for children and for elderly, infirm people to swallow.
Tachon et al., U.S. Pat. No. 5,300,302, teaches a pump dispenser for administering a metered dosage of a drug formulation. This requires a complex mechanical device and formulation properties suitable for pumping.
Gorman et al., U.S. Pat. No. 5,288,479, teaches a thickened pharmaceutical preparation comprising a hexitol and a seaweed polysaccharide. Such compositions tend to separate, and require a metered dispenser.
Ross, U.S. Ser. No. 08/114,315, EP 95939059.2 (commonly owned with this application and incorporated herein by reference), teaches semi-solid formulations and a delivery system.
However, there remains a need for more stable compositions with improved rheological characteristics. There is also a need for a reliable test system for identifying optimal formulations.
SUMMARY OF THE INVENTION
The invention relates to a drug delivery system including a combination of a squeezable container, a dispenser, and a semi-solid pharmaceutical formulation. Each of these elements of the drug delivery system has certain characteristics so that the combination (a) allows easy administration (b) of a measured amount of the drug, (c) from a convenient, preferably tamper-resistant and child-proof container, (d) with predetermined resistance to spilling, (e) while providing a suitable storage stable pharmaceutical composition with compatible components. These properties result from a variety of physico-chemical characteristics of the formulation optimized in conjunction with the type of container and dispenser.
An embodiment of the invention is a method for obtaining a suitable spill-resistant formulation comprising combining a systemic pharmaceutical agent suitable for oral administration with a semi-solid vehicle, and then conducting the following tests of the formulation: measuring initial viscosity, measuring yield value, extruding the formulation into a spoon from a container through a 1 to 5 mm orifice, observing the spreading/leveling characteristic of the formulation in the spoon, measuring spill resistance by spill start time after at least one of spoon vibration, spoon inversion, and spoon tilting at 90 degrees, and measuring viscosity after storing at elevated temperature for at least one month.
The compositions of the invention are light, water-soluble gels, which are easy to clean from a spoon bowl, and from any other surfaces which they may contact. The surface tensions of the formulations are sufficiently high to provide desirable spill-resistance, while allowing the product to be sufficiently free-flowing. In the examples of the prior Ross application, the viscosity was higher, providing a firm, spill-proof product. Here, the range of viscosity is lower, providing a freer-flowing, better leveling product, that is easier to administer with spill-resistance, but one which is more prone to spillage than the prior formulations. Thus, while the prior compositions may be considered spill-proof, the compositions set forth here are optimally “spill-resistant” but have other superior characteristics e.g. as to measurability and dispensability.
Preferred characteristics for the formulation and the method are as follows. The viscosity, when measured by a Brookflield Viscometer using “C” spindle at 20 rpm and 20-25 degrees Celsius, is between about 5,000 to 50,000 cps, preferably less than 25,000 cps. Surprisingly, a most preferred range for a formulation to be squeezed from a tube is between about 7,000 and about 12,500 cps. The formulation does not start to spill until after about 30 seconds when vibrated at a frequency of about 2-8 per second, and an amplitude up to about 1 inch. The spill start time on spoon inversion is at least about 20-30 seconds for a plastic 8 ml spoon, longer than for a syrup, and within about 1-20 seconds on spoon tilting at 90 degrees, which is slower than a syrup, but faster than prior non-spill formulations.
Preferred compositions have good shelf life, meaning that the preferred characteristics are retained after at least three months storage at a temperature of at least about 40 degrees Celsius at 75% humidity, which extrapolates under normal assumptions accepted by the U.S. Food and Drug Administration to two years shelf-life stability at room temperature. Surprisingly, in preferred embodiments using carboxyvinyl polymers such as Carbopol 974, stability may be accomplished by minimizing sodium containing substances from the formulation. Also, the Carbopol has a surprising taste masking effect for bitter drugs like acetaminophen.
Preferred compositions have Carbopol 974 in a concentration of from about 0.25% to below about 1%, in contrast to prior compositions having 1% or more. Other preferred compositions have a cellulose derivative in an amount of from about 2.5% to 3.3%, more preferably less than about 2%. A particularly preferred composition has about 1% microcrystalline cellulose and less than about 2.0% sodium carboxymethylcellulose, in contrast to prior formulations with about 2.4 to 2.8% CMC.
The configuration of the container, closure device, and receptacle and the consistency of the formulation are selected so that in response to pressure on the container when the channel closure device is open, a single predetermined unit dose of the pharmaceutical composition can be easily squeezed by manual pressure from the container through the channel into the receptacle, measured, and administered orally without spilling any of the composition from the container or the receptacle. The device may be as shown in the commonly owned Ross application or any other suitable device available to a person of ordinary skill.
This invention succeeds where previous efforts failed to provide a simple, stable, useful system of spill-resistant pharmaceutical formulations. This invention solves a previously unrecognized problem as to the rheological properties that must be optimized for a successful spill-resistant formulation.
This invention is in a crowded and mature art of oral medications, in which new dosage forms are constantly sought, at great expense and at high profit. Nonetheless, no similar composition or system has been previously discovered. Indeed, semi-solid formulations run contrary to the conventional wisdom of using either liquid or solid dosage forms.
This invention omits complex mechanical elements employed in the prior art such as pumps, syringes, and elaborate measuring vessels without loss of ability, and indeed with improved performance. This provides advantages in manufacturing, distribution, and waste disposal, and other economies as well.
The drug delivery system of the invention is counter-intuitive and inventive as indicated by the lack of commercially available embodiments of semi-solid formulations for oral administration of pharmaceutical agents. The resistant drug delivery system of the invention solves such longstanding problems with liquid formulations as spillage, and resultant underfilling of measuring spoons. The drug delivery system of the invention also overcomes the disadvantages of solid dosage forms, such as being hard to swallow.
The inventive formulations are semi-solid, not liquid or solid. Palatability, stability (a long shelf life) compatibility of components, and eas

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