พิเชฐ อุดมรัตน์ พ.บ. *

บทคัดย่อ

วัตถุประสงค์ เพื่อศึกษาถึงรูปแบบในการสั่งยารักษาโรคจิตขอ งจิตแพทย์ไทยในการรักษาผู้ป่วยจิตเภทที่ป่วยเป็นครั้งแรก

วิธีการศึกษา ให้จิตแพทย์ตอบแบบสอบถามที่มีข้อมูลเกี่ยวกับผู้ป่วยโรคจิตเภทชนิดหวาดระแวงที่เพิ่งป่วยเป็นครั้งแรกโดยให้ตอบถึงขนาดยาเฉลี่ยของ haloperidol ที่จะสั่งใช้ เมื่อใดจึงถือว่าผู้ป่วยดื้อต่อยาตัวแรก และจะเลือกใช้ยาอะไรเป็นตัวที่สอง จากนั้นนำข้อมูลที่ได้มาเสนอเป็นร้อยละและสถิติเชิงพรรณนา แล้ววิเคราะห์เปรียบเทียบข้อมูลกับการศึกษาในประเทศอื่น โดยใช้สถิติ student t-test

ผลการศึกษา มีจิตแพทย์ตอบแบบสอบถาม 98 ราย เป็นชายร้อยละ 76.5 หญิงร้อยละ 23.5 ส่วนใหญ่ (ร้อยละ 63.3) อายุ 30-40 ปี ทำงานอยู่ในโรงพยาบาลจิตเวชร้อยละ 37.8 อยู่โรงพยาบาลมหาวิทยาลัยหรือโรงพยาบาลทั่วไปร้อยละ 24.5 พบว่าร้อยละ 39 ของจิตแพทย์จะสั่งยา haloperidol ในขนาด 6-10 มก./วัน, ร้อยละ 33 จะสั่งในขนาด 11-15 มก./วัน และร้อยละ 17 จะสั่งในขนาด 16-20 มก./วัน ตามลำดับ ร้อยละ 33 ของจิตแพทย์จะคอยอยู่ 22-35 วัน จึงจะเปลี่ยนยารักษาโรคจิตตัวแรกไปเป็นยาตัวที่สอง โดยยาที่จิตแพทย์ส่วนใหญ่ (ร้อยละ 53.1) นิยมเลือกใช้เป็นตัวที่สองคือ perphenazine

สรุป จิตแพทย์ไทยส่วนใหญ่มีแนวโน้มที่จะสั่งยา haloperidol ในขนาดปานกลางให้กับผู้ป่วยจิตเภทชนิดหวาดระแวงที่ป่วยเป็นครั้งแรกในการรักษาระยะต้น และมักเลือก perphenazine เป็นยาตัวที่สอง อย่างไรก็ตาม งานวิจัยนี้ได้ศึกษาก่อนที่จะมียารักษาโรคจิตกลุ่มใหม่เข้ามาจำหน่ายในประเทศไทย จึงน่าจะได้มีการศึกษาต่อไปว่า รูปแบบในการสั่งยารักษาโรคจิตของจิตแพทย์ไทย จะเปลี่ยนแปลงอีกหรือไม่อย่างไร

วารสารสมาคมจิตแพทย์แห่งประเทศไทย 2542; 44(2): 119-124.

คำสำคัญ การสั่งยา ยารักษาโรคจิต โรคจิตเภท การป่วยครั้งแรก จิตแพทย์ไทย

* ภาควิชาจิตเวชศาสตร์ คณะแพทยศาสตร์ มหาวิทยาลัยสงขลานครินทร์ อำเภอหาดใหญ่ จังหวัดสงขลา 90110

Prescribing Habits of Thai Psychiatrists in the Treatment of a First Episode Schizophrenia

Objective To study the pattern of prescribing antipsychotic drugs by Thai psychiatrists in the acute treatment of a first episode schizophrenia.

Method Practising Thai psychiatrists, regardless of sex, age and hospitals, were asked to complete a questionnaire of a case history involving a first episode of paranoid schizophrenia. Data from the questionnaires was presented by percentages, then grouped and compared.

Results Of 98 respondents, 76.5% were male and 23.5% were female, aged 30-40 (63.3%) who worked in a psychiatric hospital (37.8%) a university hospital or a general hospital (24.5%). Most psychiatrists (36.7%) prescribed haloperidol in an average daily dose of 6-10 mg (39%), while 33% and 17% prescribed 11-15 mg and 16-20 mg respectively. Most psychiatrists (33%) would wait for 22-35 days to change the neuroleptics if the psychotic symptoms proved resistant to the first treatment with haloperidol. Perphenazine was the most popular drug of most psychiatrists (53.1%) chosen as a second neuroleptic.

Conclusions Thai psychiatrists tend to prescribe a moderate dose of haloperidol in acute treatment of the first episode paranoid schizophrenia and a mid-potency antipsychotic (perphenazine) was chosen as a second neuroleptic. However, this study was done before the introduction of novel antipsychotic drugs such as clozapine, risperidone and olanzapine. Whether this pattern will change should be further investigated.

J Psychiatr Assoc Thailand 1999;44(2): 119-124.

Key words : prescribing pattern, antipsychotic drugs, schizophrenia, first episode, Thai psychiatrists

* Department of Psychiatry, Faculty of Medicine, Prince of Songkla University, Hat Yai, Songkhla 90110, Thailand.

Over the past decade, important changes that might influence the use of antipsychotic drugs have emerged in psychiatric practices.¹ Awareness of the risks of neurological complications in aggressive or inadequately monitored use of potent neuroleptics has also increased.^2,3 Most of these findings would be expected to encourage more conservative application and dosing of neuroleptic agents.^4-7 Such a trend was documented in prescribing patterns of psychiatrists in Boston.^1,5 However, there is no information concerning this topic in Thailand. The objective of this research was to study the patterns of prescribing antipsychotic drugs by Thai psychiatrists in the acute treatment of first episode schizophrenia.

Practising Thai psychiatrists, regardless of sex, age, and hospitals, were asked to complete a questionnaire of a case history involving a first episode of paranoid schizophrenia during January-March 1995. Here is the questionnaire.

“A 28 year old unmarried businessman with a first episode of paranoid hallucinatory schizophrenia, not tense, posing no danger to himself or others, no insomnia. A monotherapy with haloperidol appears to you to be indicated. Following are 3 questions :

1. What average daily dose do you administer at the end of the first week of treatment if the patient exhibits no serious side-effects ?

2. When do you change this patient’s neuroleptics if the psychotic symptoms prove resistant to the first treatment with haloperidol ?

What do you give this patient as a second neuroleptic ?”

Data from the questionnaires was calculated by percentages, then grouped and compared. Student t-test for group differences was used for statistical analysis of the comparison between Thai psychiatrists and psychiatrists in other countries.

Of 98 respondents, 76.5% were male and 23.5% were female, aged 30-40 (63.3%) who generally worked in a psychiatric hospital (37.8%), university hospital (36.7%), or general hospital (24.5%). Only 1% worked full time in a private hospital (Table 1).

Table 1 Demographics of respondents (N = 98)

Concerning the average daily dose of haloperidol, most Thai psychiatrists (39.8%) prescribed 6-10 mg/day followed by 11-15 and 16-20 mg/day respectively (Table 2).

Table 2 Dosage of haloperidol (mg/day)*

* mean daily dosage of haloperidol = 14.1 + 6.9 mg.

If the psychotic symptoms proved resistant to haloperidol, most Thai psychiatrists (33.7%) would wait for 22-35 days while 25.5% and 18.4% would wait for only 15-21 days and 8-14 days respectively (Table 3).

Table 3 Responses to the question “When do you shift to another drug if the patient is resistant to haloperidol ?”

The most popular drug chosen by 53.1% of psychiatrists as a second neuroleptic is perphenazine. While trifluoperazine and chlorpromazine were the second and third popular drugs (Table 4).

Table 4 Names of second neuroleptics chosen by Thai psychiatrists

* Still use the same drug

** Thiothixene, Clozapine, Lithium, no answer

Every culture has its own characteristics of psychiatric practice including the pharmacotherapy of schizophrenia.⁸ When comparing our data with data from other countries in Asia in which similar surveys were performed,⁹ it was found that Thai psychiatrists prescribed haloperidol in a slightly higher mean daily dosage than psychiatrists in Malaysia and Singapore but it is not statistically significant (p = 0.40 and p = 0.33 respectively). However, when comparing with Taiwan and Hong Kong counterparts it was found that Thai psychiatrists prescribed higher mean daily dosage of haloperidol statistically significant (p < .001). It seems that ASEAN psychiatrists would prescribe around 12-14 mg/day of haloperidol while East Asian psychiatrists would prescribe a smaller dose around 9-10 mg/day. But if we look at the daily dosage range of haloperidol, it is found that Thai psychiatrists prescribe at 6-10 mg.This similar pattern occured in both ASEAN and East Asian countries (Table 5). When we convert 6-10 mg of haloperidol to the dosage of chlorpromazine equivalents, it is approximately 300-500 mg of chlorpromazine which is the moderate daily dose.¹⁰ This study yield a results similar to the study of antipsychotic drugs used in Boston in 1989 and 1993.¹ From the Boston study, the overall mean prescribed chlorpromazine equivalent daily neuroleptic dose was approximately 300 mg.¹

Concerning the time shifting from haloperidol to the second drug, Thai psychiatrists would wait for 3-5 weeks which was similar to Malaysian and Taiwan colleagues while psychiatrists in Singapore and Hong Kong would shift earlier around the first and the second week respectively (Table 6).

Table 5 Dosages of haloperidol (mg/day) prescribing by psychiatrists in some ASEAN and East Asian countries

* Thailand vs Taiwan p = 0.0000

** Thailand vs Hong Kong p = 0.0001

Table 6 The time shifting from haloperidol to the second drug

Regarding the second neuroleptic chosen, it seemed that trifluoperazine and chlorpromazine were the popular drugs among psychiatrists in these countries. Both drugs were chosen as the “top three” (Table 7). But Thai psychiatrists chose perphenazine as a second neuroleptic. This may be due to the belief of some psychiatrists that paranoid patients would response better with perphenazine or have less extrapyramidal side effects compared with haloperidol.

Table 7 Names of the second neuroleptics chosen by psychiatrists in some ASEAN and

East Asian countries

It should be noted that only 1% of Thai psychiatrists would choose clozapine, a novel antipsychotic, as a second drug. Clozapine was not officially available on the Thai market at the time of the study. It was possible that the psychiatrists who chose clozapine might have had previous experience using this drug abroad or might have participated in a clinical drug trial.

There were two limitations of this study. First, questionnaire required haloperidol as a first choice, not allowing psychiatrists to choose their own preference. Secondly, the questionnaire did not ask the reason for the choice of the second neuroleptic drug. In view of changing prescribing patterns, future research should allow psychiatrists preference for the first line drug. In addition, research should also indicate the reasons for choosing the second neuroleptic. Moreover, this study was done before novel antipsychotics such as clozapine, risperidone and olanzapine were officially released on the Thai market. Whether this pattern will change should be further investigated.

Thai psychiatrists tend to prescribe a moderate dose of haloperidol in acute treatment of the first episode paranoid schizophrenia and would wait 3-5 weeks to change the neuroleptic if the psychotic symptoms proved resistant to haloperidol. Perphenazine, a mid-potency antipsychotic, was chosen as a second neuroleptic. Finally, the author recommends future research to find out any changes of prescribing pattern of Thai psychiatrists in this current situation.

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9. Data presented in the expert meeting on the topic of “non-compliance investigation”, presented the results of similar surveys before starting Prelapse program. 23 June 1995 at Pan Pacific hotel, Bangkok.

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