Abstract:
A method for the treatment of acne is provided which results in the reduction of vestibular side effects following administration of oral tetracycline antibiotics.

Description:
FIELD OF THE INVENTION 
     This invention relates to methods for the treatment of acne, and in particular to methods for the treatment of acne involving the use of oral tetracycline antibiotics. 
     BACKGROUND OF THE INVENTION 
     Oral tetracycline antibiotics are frequently used in the treatment of acne. One of the most effective oral tetracycline antibiotics used in the treatment of acne it is minocycline. All tetracycline antibiotics are known to have some side effects. These side effects include vestibular symptoms such as vertigo, dizziness or blurred vision. These effects are sometimes disabling. See, Gould &amp; Brookler, Arch. Otolarang. Vol. 96, p. 291 (1972); Williams et al., Lancet, Sep. 28, 1974, p. 144-45; Fanning &amp; Gump, Arch. Intern. Med., Vol. 136, pp. 761-62 (1976). Headache and general malaise, along with gastro-intestinal symptoms such as the diarrhea, nausea, gas, or cramps also occur. Dry nose and dry mouth are also occasionally encountered. 
     Dosage forms of oral tetracycline antibiotics are typically constructed with a view towards achieving rapid dissolution rates. Rapid dissolution is believed to be essential to the effectiveness of these drugs. The driving force behind this practice is the understanding that rapid dissolution leads to rapid assimilation through the gut lining, where the antibiotics are then transmitted through the blood stream to the skin, where they are active against bacteria associated with acne. The U.S. Food and Drug Administration (FDA) has established standards for dissolution rates for various oral antibiotics. These standards set minimum dissolution rates. For example, the FDA standard for oral minocycline is that 75 percent of the stated dosage must have dissolved within 45 minutes, under standard U.S. Pharmacopea test conditions. Commercial products are typically engineered to have a dissolution rates which are substantially faster than that required by the FDA. All of this is based upon the generally accepted belief in the art that, while dissolution rates enhance the effectiveness of the antibiotic, once the FDA minimum dissolution rate is achieved, all products have equivalent safety and efficacy. 
     SUMMARY OF THE INVENTION 
     It has been discovered that the dissolution rate of oral tetracycline antibiotics, especially minocycline, can affect the occurrence of vestibular side effects. Specifically, too rapid dissolution of oral tetracyclines increases the incidence and severity of vestibular side effects. By reducing or slowing the dissolution rates of the antibiotics, the incidence and/or severity of vestibular side effects can be reduced significantly. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Vestibular reactions are an undesirable and sometimes seriously disconcerting side effect of minocycline therapy. According to the present invention, it is possible to provide persons susceptible to such side effects with the benefits of minocycline therapy while diminishing the incidence and/or severity of these side effects. This is accomplished by adjusting the dissolution rate of the minocycline in its dosage form so that, while an effective concentration of minocycline is achieved in the blood stream of the patient, vestibular side effects are greatly reduced. 
     In a preferred embodiment of the invention, the minocycline dissolves at a rate of only 15 percent within the first 15 minutes, 35 percent within 30 minutes, 50 percent within 45 minutes, and 80 percent within one hour. It is also advantageous to use a dissolution rate of 20 percent within 15 minutes, 50 percent in 30 minutes, 75 percent within 45 minutes and 100 percent dissolution within 60 minutes. Dissolution rates as fast as 30 percent within 15 minutes, 60 percent within 30 minutes, 75 percent within 45 minutes and complete dissolution within 60 minutes or even as fast as 35 percent within 15 minutes, 80 percent within 30 minutes and substantially complete dissolution within 45 minutes can be used. Preferred dissolution rates are within the range of 20 to 40 percent in 15 minutes, 50 to 80 percent in 30 minutes, and 70 to 95 percent in 45 minutes. Faster rates of 25 to 35 percent in 15 minutes, 60 to 80 percent in 30 minutes and 80 to 100 percent in 45 minutes are useful. It will be understood however, that the faster dissolution rates do not achieve as significant a reduction in the reduction of unwanted side effects as the slower dissolution rates. 
     Minocycline is available from a variety of sources. Various commercial products containing minocycline as their active ingredient have a variety of the dissolution rates. In the following example, slower dissolving minocycline is compared with fast-dissolving minocycline. 
     A blinded cross-over study of the vestibular side effects of minocycline involving 32 female subjects was conducted. The subjects were given either a fast dissolving or a slower dissolving dosage form of minocycline. The doses for the subjects were adjusted on the basis of each subject&#39;s total body weight and were in the range typically used for the treatment of severe acne. Subjects weighing 50 to 69 kg were given one-hundred milligrams. Subjects weighing 70 to 89 kg, the dose were given one hundred fifty milligrams and subjects above received 90 kilograms, 200 milligrams. This dose was given once a day at 5 p.m. Subjects received one of the two dose forms for four days. After a two week washout, each group &#34;crossed over&#34; and received the dosage form that they had not received during the first four day period. Each subject was required to maintain an accurate diary of vestibular side effects. The diary recorded the number of days that each subject experienced vestibular side effects and the number of incidents of each symptom. The 32 subjects were evaluated over a five day period, yielding 160 person-day measurements per treatment group. The number of days that each subject recorded a side effect and the severity of that side effect the reported in Table 1. 
     From Table 1 it can be seen that a total of 27 incidents of vestibular side effects occurred in the fast dissolving treatment group, compared to only five incidents in the slower dissolving group. The severity of the vestibular side effects are reported on a scale of 1 to 4. With 1 indicating slight severity, 2 indicating mild severity, 3 moderate, and 4 severe side effects. 
     The dissolution rates for the fast dissolving dosage form and the slower dissolving dosage form are set forth below. 
     
                       TABLE 1______________________________________Vestibular Side Effects             No. of               Severity             Time                 Cate-Symptom  Severity Intervals                      Duration    gory______________________________________Patients Treated With Slower-Dissolving Minocyclinedizziness    slight   2        8:00 am-4:00 pm                                  1dizziness    slight-mild             4        all day     1.5dizziness    mild     1        on and off  2dizziness    slight   1        all evening 1dizziness    slight-mild             2        morning thru mid day                                  1.5Patients Treated With Fast-Dissolving Minocyclinedizziness    slight   2        7:00 am-12:00 pm                                  1blurred vision    slight-mild             2        8:00 am-3:00 pm                                  1.5dizziness    slight   2        7:00 am-12:00 pm                                  1dizziness    slight   2        8:00 am-2:00 pm                                  1dizziness    slight   2        7:00 am-2:00 pm                                  1dizziness    slight   2        7:00 am-3:00 pm                                  1dizziness    slight   2        morning-late afternoon                                  1dizziness    slight   2        morning-late afternoon                                  1dizziness    slight   2        morning-late afternoon                                  1dizziness    slight   1        1 hour      1dizziness    slight   1        2 hours     1dizziness    slight   1        about 1-2 hours                                  1dizziness    slight   1        about 1.5 hours                                  1dizziness    slight   1        2 hours     1blurred vision    slight   1        1 hour      1dizziness    slight   1        2 hours     1dizziness    slight-mild             2        7.5 hours   1.5dizziness    mild     1        6:00 am-8:00 am                                  2vertigo  mild     1        2:00 am-8:00 am                                  2dizziness    mild     1        6:00 am-8:00 am                                  2vertigo  mild     1        2:00 am-8:00 am                                  2dizziness    mild     1        6:00 am-8:00 am                                  2vertigo  mild     1        6:00 am-8:00 am                                  2dizziness    mild     1        6:00 am-8:00 am                                  2vertigo  mild     1        6:00 am-8:00 am                                  2dizziness    mild     1        6:00 am-8:00 am                                  2vertigo  mild     1        6:00 am-8:00 am                                  2______________________________________ 
    
     
                       TABLE 2______________________________________Fast Dissolving   Slow DissolvingTime (Min.)     % Dissolution                 Time (Min.)                           % Dissolution______________________________________0         0.0         0         0.015        100         15        3030        100         30        6745        100         45        8860        100         60        95______________________________________ 
    
     The cause of the effectiveness of this invention is not known. However, it can be speculated that the dissolution rates called for by the present invention allow the vestibular organs to acclimate themselves to the presence of the minocycline, and thereby avoid unwanted side effects. This explanation is consistent with the avoidance of vestibular side effects even through the use of both slow and fast dissolving dosage forms may achieve the same level of minocycline in the blood stream. 
     The foregoing example is given by way of illustration only. The scope of the invention is defined only by the following claims.