Methyldopa in the Treatment of Hypertension*

BRUCE L. GILMORE, M.D.?

Instructor in Yvfeciicine, Georgetmn Unioersity School of Medicine
EDWARD 0.CREIS, M.D., F.A.C.P.
Professor of Medicine, Georgetown University School of Medicine; Senior Medi-
cal Inwstigator, Veterans Adminislration Hospital, Washington

S ISCE t,he initial comm~~ni~ation of Oates et-
all reporting that methyldopa lowered blood
pressure in hypertensive patients additional stud-
ies hal-e attested to the efficacy of this drug as
an antihypertensi~e agent.`-? Over the past 21/
years methyldopa (Aldome@) has been utilized
in this clinic usuaily in conjunction with sul-
fonamide saluretic agents in the long-term treat-
ment of hypertensive outpatients. The drug was
compared with guanethidine in 13 patients for
pcriotls averaging 6 months on each agent. In
addition, adverse hcpnt,ic effects of met,hyldopa
11:~~ been documented.

Materials and Methods

During the periotl of study 33 patients were
treated in the hypertension clinic of the Mt.
.JJto Veterans .~clrninist,ration Hospital with
mcthylriopa. Tcvclvo patients had severe hyper-
tension with 4 in the malignant phase, 19 with
moilcr:lte hypcrtcnaion, and 2 with mild hyper-
tcnsion.$ The me:m age was 45 years, and 25
of the group were Scgroes. Only 3 !Jatients ex-
nibitpd normal electrocardiograms, the majority
&owing left ventricular hypertrophy. Twelve
Il:ltic>nts had blootl urea nitrogrn levels prior to
tllor:ll)y in excess of 25 mg. per 100 ml. of blood.

The interval bctxveen clinic visits averaged 2.5
w-eek~. At each clinic visit, blood pressure record-
ings in the supine, sitting and crcct positions
ww taken by a physici$ti. Methyldopa was ad-
mini~tcred in divided doses 3 times daily, Doses

* Tilis stud:7 ins qqjorted in part by Grant H-720
from I be United Stntrs Public Health Service.
f Formerly Clinirul Investigator, Veterans Adminis-
tration Hospital, Washington, D.C.; present, address:
1203 Sorth Quaker Lane, -Uexandria, Virginia 22302.
1 In the hypertensive grading of patients we utilized
the tnriterin of the Veterans .%dministration Cocperative
Stud? on Antihypertensive -agents, published in "A
doublr4lind rontrol study of antihypertensive agents,"
hh. Int. Med., 1960. 106, 81.

were adjusted at each clinic visit in order to ob-
tain optimal blood pressure control within the
range of tolerable side-effects. The sulfonamide
diuretics which were used were either hydro-
chlorothiazide, 50 mg. twice daily, or chlor-
thalidone, 100 mg. once daily.

Bromsulfalein (BSPf , serum alkaline phospha-
tase, serum glutamic oxaloacetic transaminase
(SGOT), and blood urea nitrogen (BUN) deter-
minations were done after the patient had been
instructed to fast overnight and omit breakfast.
The amount of BSP retention was determined
according to a modified method of Greene. Alka-
line phosphatase was done by the method of
Bodansky. SGOT was determined by a modified
Reitman-Frankel method utilizing Dade@ re-
agents, and the BUN was estimated with the
Technicon@ auto-analyzer.

Remits

Efiectiveness of therapy. Blood pressure
changes in only 24 patients will be discussed,
since information regarding the percentage
change in blood pressure was not pertinent for 4
patients whose methyldopa was discontinued
because of side-effects and for 5 patients who
were transferred directly from guanethidine to
methyldopa without an intervening control pe-
riod.

Twelve of the 24 patients either became nor-
motensive or had average mean blood pressurel
readings that were more than 20 per cent lower
than the pretreatment mean pressures in both
the supine and erect positions./ An additional 4
patients exhibited average mean blood pressures
during the treatment period that were lower than
their pretreatment levels by 20 per cent or more
in the erect but not in the supine position. The

3 Mean blood pressure = diastolic blood pressure +
J/s pulse pressure.

11 Detailed tabular data on individual cases can be .
obtained by writing to the authors.

13


14

METHYLDOPA FOR HYI'ERTESSIOS-GILMORI: LSI) FRL;I~   Jauuarq, l!N%i

average duration of therapy in these 16 patients
was 40 weeks (range 13 to 96 weeks). The aver-
age dose of methyldopa was 1,365 mg. (range
540-2,375 mg.) per day. Fourteen of the 16 re-
ceived saluretic agents concurrently.

The remaining 8 patients did not demonstrate
reductions in their average blood pressures dur-
ing the treatment period that were greater than
10 per cent of their pretreatment values. The
average maximum dose of methyldopa in these
patients was 1,906 mg. (range 1,750-3,000 mg.)
per day. Seven of the 8 were treated concurrently
with oral saluretic agents.

Tolerance. The records of 10 patients who were
maintained with decreases of 20 per cent or more
in mean blood pressure in the erect position
were evaluated at 6 weeks, 3 months, and at the
end of therapy. Dosage and blood pressure levels
at intervals as close as possible to these periods
were tabulated. Three of the 10 patients evi-
denced manifestations of tolerance (table 1). The

Transient symptoms suggesting ort,hostatic
hypotension were noted in 20 of the 33 pnticnts.
For the most part bhese symptoms consisted only
of mild dizziness on arising in the morning, but
3 patients experienced syncope which did not rc-
cur when dosage was rcduccd.

Four patients complained of diminished sesual
drive after beginning methyldopa. In 1 caac re-
duction in dosage sufficed to restore potency. In
another patient the addition of n placebo with-
out reduction in t'he dose of methyldopa led to
restoration of normal potency. In the 2 remain-
ing patients the complaint continued after their
treatment was changed. It is, therefore, unlikely
that the impotence was related to mcthyldopa in
3 of the 4 patients.

Four patients voluntecrcd that they were har-
ing frequent dreams which seemed to be related
to therapy. The dreams ceased, howcvcr, despite
continuation of treatment. Four patients com-
plained of "tenseness"  and nerl*ousness while

TABLE 1: Tolerance to Alpha Meth~ltlopa

                Duration of Treatment                        -

6 weeks                 3 months                  Final'

                      Blood Pressure    Daily Dose                                   Daily Dose

                      (mm. Hg)      Alpha     Blood Pressure  IDa$D;SC    Blood Pressure     .4lpha
                             Methyldopa
                                 bw.)       pm. Hg)     Methyldopa     ,mm. Hg)
                                                       us-.)        Me:h~l~;pa 6


                  Supine   Standing          Supine   Standing          Supine I Standing
                   I---------------
Tolerant patients (3)    157/103  159/112  1,333   173/113  163/116   1,500   165/114 ~ 170/114   2,150
Nontolerant patients (7)  145/96   131/95   1,000   147/99   140/105   1,214   133'g6  '
                                       I 118/88   1,321

* Average duration of treatment for tolerant patients, 6 months; for nontolerant patients, 12 months.

average daily dose of these patients at 6 weeks
was 1,333 mg. and at 6 months 2,450 mg., all of
the patients being treated throughout with
saluretic agents. The blood pressure was slightly
higher at 6 months despite the higher doses. In
the remaining 7 patients the average daily dose
was 1,000 mg. at 6 weeks and 1,321 mg. at 12
months with the average blood pressure lower at
the 12-month interval. Five of these 7 patients
were treated concurrently with saluretic agents
throughout the entire period.

Side-effects. Side-effects were minimal. Drow-
siness at the init,iation of treatment was noted in
most patients. It usually disappeared after sev-
eral days on a given dose to recur again for a
few days if the dose was increased. One patient,
however, experienced persistent drowsiness over
the course of 6 months, with the result that his
employer complained that the patient was con-
stantly falling asleep at his desk.

taking methyldopa. Other complaints less fre-
quently encountered were dry mouth in 2 cases,
headaches. in 2, and constipation in 1. These
minor subjective complaints were not neces-
sarily related to the use of the drug.

Side-effects necessitating discontinuation of
methyldopa occurred in only 3 instances. In 1,
referred to above, persistent drowsiness ceased
when the patient's therapy was changed to
guanethidine. A second patient complained of
vomiting and headaches which came on ap-
proximately 20 minutes after taking his medi-
cations. These symptoms recurred on 2 separate
trials, and the patient refused further treatment
with the drug. One other patient developed a
macular, pruritic skin eruption after 4 weeks of
methyldopa therapy. The rash cleared com-
pletely within 2 weeks of discontinuing treat-
ment, and a second trial of the drug was not
attempted.


I)r!ig  reactions. Fever and alterations in
Il<al)atic function tests associated with methyl-
,lol)a athninistration have been reported in the
liteyature.3. 3. T. X. !) In the present series of 33
ljatients 2 cases of chills occurred and each was
:iFsociated with alterations in liver function tests
but without jaundice. Liver biopsy was obtained
:lt the height of the illness in 1 of these patients
I 1)X) and showed changes consistent with
nliltl hepatitis due to drug reaction. Retesting
\vith methyldopa was accomplished 9 months
later at a time when all tests of liver function
had returned to normal. The same alterations
in  serum glutamic  oxaloacetic transaminase
levels, cephalin flocculation tests, and brom-
+ulfalein retention that had been present in the
initial illness recurred on retesting.

The second patient. W.P., experienced the on-
.<et of chills 13 weeks after initiation of therapy
at a time when he was receiving 2?250 mg.
methyldopa per day, chlordiazepoxide. and hy-
rlrocl~lorotl~iazidc. ,4 mild elevation in the se-
rum glutamic oxaloacetic transaminase level to
90 units and a bromsulfalein retention of 8 per
cent were noted at this time. The transaminase
level fell to 61 units in spite of continued ad-
ministration of the drug. Retesting with l/2 the
previously administered dosage of methyldopa
following a 3-month cessation did not cause a
recurrence of the chills, but the transaminase
level rose from an initial level of 8 to 61 units
at the end of the month. Bromsulfalein retention

n-as essent,ially unchanged, falling during this
montll from 7.7 to 5.i per cent..

One case of jaundice occurred in ,a patient
nllo na:: known to bc alcoholic. The acute onset
of severe ictcrus was noted after he had taken
mcthyldopa for 10 weeks in a dose of 750 mg,
per day togctlicr with clilortlialidone~ 100 mg.
per day. Liver biopsy at the time of the acute
illness ehowec~ florid cirrhosis. Retesting with
mctli~ldol~a was accoml~lislietl 3'$$ months later,
thr patient receiving 750 mg. daily for 6 weeks.
There was no recurrence of jaundice during this
time. Tests of hepatic function, performed dur-
ing the sisth week, did not reveal any alteration
from the slightly abnormal values obtained prior
to retesting. Ko other symptoms or physical
signs of hepatie disease were encountered in the
present series.

Fifteen patients n-ho llad been taking methyl-
dopa continuously  had normal bromsulfalein
retention . serum alkaline phosphatase levels, and
~cruni glutnmic oxaloncetic transaminase levels
after an average period of 10.7 months (range 5

weeks to 17 months). The mean dose was 1,535
mg. (range 750-2,750 mg.) per day at the time
the determinations were done. Two patients who
died of renal failure during the course of this
study did not show evidence of hepatic disease
in gross or microscopic postmortem examinations
of their livers.

Comparison with guunethidine". Thirteen pa-
tients were treated with guanethidine and salu-
retie agents for sufficient periods of time to allow
comparison with their response to methyldopa
plus saluretic agents. The average duration of
treatment with guanethidine was 30 weeks
(range 3 to 94 weeks) and 25 weeks with meth-
yldopa (range 10 to 57 weeks). The average
blood pressure on guanethidine therapy was
166/109 mm. Hg supine and 139/100 mm. Hg
in the erect position. The average supine blood
pressure during methyldopa was 166/112 mm.
Hg while the average erect blood pressure was
151/109 mm. Hg. The difference in mean ortho-
static blood pressure levels on the 2 drugs was
significant (P < .02). Twelve of the 13 patients
received saluretic agents concurrently with both
drugs while the remaining patient did not. The
average daily dose of guanethidine was 32 mg.
(range 12.5-69 mg.) taken once daily, and 1,610
mg. of methyldopa (range 1,125-2,250 mg.)
taken in 3 divided doses.

Two of the above patients were transferred
from methyldopa to guanethidine because of
failure to respond significantly to large doses of
the former. Seven other patients in the com-
parative series were receiving daily doses of
methyldopa of 2,000 mg. or more at the time of
transfer. On guanethidine, all of these patients
were maintained with lower orthostatic blood
pressures and in 4 with lower supine blood pres-
sures as well. Four of these 9 patients were
classified as severe hypertensive patients and 5
as moderate. Eight of the above mere t,reated
with saluretic agents on both regimens and 1 was
not. Another patient was transferred to guaneth-
idine after his blood pressure rose to 230/150
mm. Hg with severe daily headaches ancl weight
loss of 9 pounds which occurred while he was
taking methyldopa plus chlorthalidone. His
blood pressure has since been maintained for
over 1 year at average levels of 156/102 mm.
Hg. supine and 128/91 mm. Hg erect with
guanethidine plus a saluretic agent.

One patient with malignant hypertension who

* Ismelin@, a product of Ciba Pharmaceutical Com-
pany, Summit, New Jersey.


~ETHYLD~P~ FOR HYPERTENsIO~-GIL~~ORE hm FREIS   January, 1965

had manifested erratic control while taking
guanethidine with hydro~hlorothiazide for 27
weeks was transferred to methyldopa and chlor-
thalidone. He maintained lower blood pressure
levels during 18 weeks of treatment with the
latter drug in an average daily dose of 2,000 mg.
Higher blood pressures then recurred in spite of
increasing doses. The blood urea nitrogen level
had been 61 mg. per 100 ml. at the beginning of
methyldopa therapy. Because of his mental con-
fusion it is not certain that he took his pills cor-
rectly during this period. He subsequently died
in renal failure. The 2 remaining patients in the
series, both with moderate hypertension, main-
tained equally good control with either methyl-
dopa or guanethidine.

Symptoms of orthostatic hypotension lvere
more frequent and of greater severity while the
patients were taking guanethidine. However, in
no case was it necessary to discontinue treatment
with guanethidine because of orthostatic hypo-
tension; brief discontinuance and subsequent re-
duction of dosage were sufficient to alleviate the
problem.

Seven of the 13 patients developed failure of
ejaculation while taking guanethidine. In no
ease, however, was guanethidine discontinued
because of this side-effect although the patients
were informed that guanethidine was the causa-
tive agent. Only 1 of the 13 patients complained
of any change in sexual function while taking
methyldopa. This consisted of transitory impo-
tence responding to a brief reduction in dosage.
In spite of the side-effects noted above, none of
the 13 patients expressed a preference for meth-
yldopa over ~anethidine. Two patients had
occasional episodes of diarrhea while taking
guanethidine whereas none complained of bowel
disturbances with methyIdopa.

Blood urea nitrogen levels were taken serially
in 10 patients prior to and after completion of at
least several months on each type of therapy.
Excluding the patient who died in renal failure
the average blood urea nitrogen level was 32 mg.
per cent during methyldopa treatment as com-
pared to 36 mg. per cent during treatments with
guanethidine. The difference was not statistically
significant and could be accounted for entirely by
increase in blood urea nitrogen in 2 asotemic
patients whose diastolic blood pressure levels in
the erect position were 18 and 25 mm. Hg lower,
respectively, during the guanethidine treatment
period. In 1 of these patients a reduction in
guanethidine dosage with consequent higher
orthostatic blood pressures resulted in lower
levels of blood urea nitrogen.

Comments

In the present study methyldopa in conjunc-
tion with oral diuretics proved effective in main-
taining significant decreases in blood pressure in
16 of 24 patients. The use of saluretic agents
seems indicated in view of the potentiation of
action of methyldopa noted by ourselves as well
as others.2~ 3, 0, i, lo, I* Furthermore, problems of
fluid retention noted occasionally on administra-
tion of methyldopa"~ 7, l2 were obviated. Dollery
and Harington' used methyldopa alone in doses
up to 4.0 Gm. daily. Seven of 59 patients failed
to respond. Cannon et al* employed doses up to
8.0 Gm. per day and reported that 31 of 33 pa-
tients had a significant response, Onesti et allo
administered up to 2.8 Gm. per day and found
that 13 of 24 patients obtained a significant anti-
hypertensive response in the erect, position; when
hydrochlorothiazide was added in 7 nonre-
sponders, 6 of these obtained a significant fall in
blood pressure.

Tolerance to methyldopa has been noted by
other investigators. Cannon et, al-" noted that the
dosage requirement of most patients increased
somewhat after they were discharged from the
hospital. Two of their 33 patients required dis-
continuation of methyldopa because of tolerance
after 7 and 11 months, respectively. Dollery and
Warington' noted that some increase in dosage
was often necessary on the early outpatient
visits after patients `;i'ere discharged from the
hospital. They also observed that a small num-
ber of their patients continued to require in-
creasing dosages during prolonged t#reatment.
Bayliss and Harvey-Snnth"2 noted tolerance in
4 of their 20 cases so that doses of 3 Gm. or more
per day were no longer effective. Daley and
Evansi noted significant tolerance in 2 of 20
patients. SrnirkO reported that increased doses
were required to maintain the initial blood pres-
sure falls in 6 of 14 patients. In 2 of these pa-
tients the increases were nearly 3-fold. In the
present study it was found that while 3 of 10
patients manifested tolerance, requiring an aver-
age dose at 6 months that was nearly double
the average dose at G weeks, the remaining 7 pa-
tients did not manifest tolerance after an aver-
age of 12 months of continuous treatment.

Drug reactions to n~ethyldopa were first noted
by Gillespie and co-workers." They rel)orted 2
patients who developed fever within 2 weeks
after the initiation of treatment \vith racemic
mcthyldopa. Discontinuance of medication was
associated with cessation of fever in both pa-
tients. On readministration of the thug, fcvcr


l~,ll. &, . \' 0. I      .\IEDIC;\L .$SS;iLS OF THE DISTRICT OF COLUNBIA             17

I~c7,~i~rrccl in 1 patient Gthin 3 days. In the second
1b;iticnt fci-cr did not recur with rcatlministr~tion,
I,iit c~lcv:~tions of serum alkaline phosphutnse,

ri~;m.~:~inin:~sc  antI bilirubin levels similar to
rliose that had been Inesent with fever recurred
jvithin 2 days. Leonard et al8 reported 3 patients
in whom febrile reactions occurred within 3
\v(~ks of initiation of treatment. Methyldopa
1~;~s reachuinistered to 2 of these patients with
re1iroduction of the fever. Sheps et al9 reported
that fever occurred within 3 weeks of initiation
of methyltlopa in one of his patients and was
:is:aoriatccl Iv-it11 an elevated serum glutamic
osaloacctic transaminase level. The latter be-
C;UW normal 10 days after discontinuation of
the drug. Retesting was not accomplished in
this case. One brief note of the results of liver
t)iol)sy in another patient has been recorded."
Thr liver bec:mie normal with discontinuation of
methyldopa in this patient, but it is not stated
whether retesting was undertaken.

Tlir patient with hepatic injury in the present
&c's represents the first reported case demon-
strating hcpatic changes by biopsy during t.he
:icute illness and recurrence of alterations of
hcalj;rtic function tests when metliyldopa was
f~catl~~linistcl~ctl. &reral points arc, therefore, of
inttrcst. The alterations present in the biopsy
~liecinien ncrc consistent with 3 hypersensitivity
rcx:iction with spotty necrosis but were not typi-
cal of "allergic cliolangiolitie" with bile stasis'"
w .>cen n-ith chlorpromazine. The tests that were
uio~t u~ful in follolving the hepatic injury were
thca ~(7uni glutamic oxaloacetic transaminase,
tlicx cc~1~li:ilin florculntion test, and bromsulfalein
retention.  Elel-ation of the  serum glutamic
osalo:icctic transtlminase lcvcl and a change in
rc1ihalin flocculation tlid not occur until 9 days
after the start of retesting and p,ersisted for at
Icast. 2 weeks after nietl~pldol~a ~-as discontinued.

Rrl-iew of the literature indicates that fever
and alteration of hcpatic function tests are in-
frequent complications of the use of methyl-
dopa. So case of death or permanent alteration
of he1ratic function has been reported. It appears
that he1)atic injury induced by methyldopa re-
quircls some type of individual hypersensitivity
to the tlrug and is reversible with discontinua-
tion of the drug.

Jloat investigators have noted that methyl-
dopa produces less orthostatic hypotension than
(1~~ gu:mcthicline. The results in the 13 cases
reported above in which guanethidinc and meth-
vltlo1ia wcrc compared is consistent with this
iinprcs~ion. In reviewing the literature, average
supine anal erect blood pressures of 62 patients

treated with methyldopa alone, reported in 5
articles,", 1~ 11, l6. 17 were 159/95 mm. Hg and
141/91 mm. Hg, respectively. Average supine and
erect blood pressures of 62 patients who were
treated with guanethidine alone, reported in 5
different articles,ys-22 were 169/103 mm. Hg and
134/90 mm. Hg, respectively. Tests for stat'istical
significance were not attempted for obvious rea-
sons, but the finding of lower supine pressures
with methyldopa  when orthostatic diastolic
pressures were equivalent tends to substantiate
a widely held clinical impression.

In spite of the higher incidence of side-effects
while taking guanethidine, patients continued to
take their medications and none requested a re-
sumption of methyldopa. Many patients pre-
ferred the small number of tablets and once
daily administration associated with guanethi-
dine. The shorter onset and effective duration of
action of methyldopa were occasionally found to
constitute a practical advantage. Initiation of
effective therapy can be more rapid, and ortho-
static hypotension, if it occurs, can be eliminated
more rapidly through a reduction in dosage.

Methyldopa was not compared with drug
regimens generally used for less severe hyper-
tension in this clinic, namely, reserpine plus
saluretic agents or reserpine, saluretic agents
and small doses of hydralazine. The low inci-
dence of side-effects, lack of orthostatic hypo-
tension, simpler titration of dosages, and equiva-
lent frequency of administration (3 or 4 times
daily with hydralazine) would seem to contra-
dict replacement of these regimens with methyl-
dopa as the first choice of treatment in most
patients with benign hypertension.

Summary

Twenty-four male patients with moderate to
severe hypertension were treated with methyl-
dopa for an average period of 9 months (range
2.5 to 22 months). The mean daily dose was
1,390 mg., usually in conjunction with a ealu-
retie agent. Sixteen of the 24 patients main-
tained a significant reduction of blood pressure.
Tolerance was observed in 3 cases. The side-
effects were minimal and consisted principally of
drowsiness during the initial period of treatment.

Two instances of febrile reactions associated
with disturbances in liver function tests were
observed. Abnormalities of liver function re-
curred when methyldopa was reinstituted. In 1
of these patients needle biopsy taken during the
acute illness demonstrated toxic injury to liver
cells compatible with drug-induced hepatitis.


18         METHYLDOPA FOR HYPERTENSIOK-GILRIORE ASD FREIS   January, 1965

7vIethyldopa was compared with guanethidine
in 13 patients. Treatment with methyldopa was
associated with fewer side-effects than with
guanethidine but was not preferred by most pa-
tients, largely because of the large number of
tablets and greater frequency of dosage required.
Orthostatic reduction of blood pressure usually
was greater with guanethidine.

Methyldopa, in the form of Aldome@, was supplied
by Dr. E. L. Foltz of Merck, Sharp and Dohme. We
wish to thank Drs. Jay N. Cohn, William C. Heath,
Myron H. Luria, Flavio D. Sassen and Harold D.
Schnaper who participated in the clinic management of
the above reported patients.

1:


2.


3.


4.
5.


6.
7.
8.


9.


10.


11.


12.


13.
14.

15.


16.


17.


18.


19.

20.




21.


22.

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RIRKENDALL, W. M., AND OTHERS: Hemodynamir and
clinical effects of guanethidine, presented at thf
*Symposium on Guanethidine, held at the Univer-
sity of Tennessee College of Medicine in Mcm-
phis, April 22,196O.
FROHLICH, E. D., .~ND FREIS, E. D.: Clinical evalua-
tion of guanethidine-a postganglionir sympa-
thetic blocking agent. Ibid.
CHAXDRASEKAR, R. G., AND OTHERS: Amer. Heart J.,
1962,63,309.
P.AGE, I. H., AXD Dus~ax, H. P.: J.A.M.A.. 1959, 170,
1265.

~ti, CARD? W. I., ASD OTHERS: Lancet? 1953, 1, 663.
Ii. GALAL, E. E.: Brit. J. Pharmacol.. 1955, 10, 305.
18. HUDSOX, P. B., MITTLEXAN, A.. AXD PODBERECEC, M.:
  New Eng. J. Med., 1954,251,641.
19. LOUIS, L. H., ASD COSN, J. W.: J. Lab. Clin. Med.,
  1956, 47,20.

Licorice for Salt-losing Nephritis-Parrish

      (Con timed from page 3)
PETERS, J. P., WAICEUAN, A. M., EISES~IAX, .4. J., .~ND
LEE, C.: J. Clin. Invest., 1929, 6, 517.
LEVERE, A. H., AND WESSON, L. G., JR.: Sew Eng. J.
Med., 1956, 255,373.

N~SSBAUM, H. E., BERXHARD, W'. G., ASD M.~TTIA,
V. D., JR.: Ibid., 1952, 246, 289.
JOINER, C. L., AND THORNE, M. G.: Lnncet, 1052, 2,
454.

MURPHY, R. TT., COFFYAK, E. W., PRISGLE, B. H., AND
ISERI, L. T.: Arch. Intern. Med. (Chicago), 1952,
90,750.

FALSETTI, H., AND KUSIX, A. S.: New Eng. J. Med.,
1963, 268,598.

20. CAPRETTI, G., .4SD M4GSAN1, B.: Gior. Clin. Med.,
  1953,34,649.
21. KRAUS, S. D.: J. Esp. Med., 1957, 106, 416.
22. KRAUS, S. D.: Ibid.: 1958, 108, 325.
23. VASDER, A. J.. AXD OTHERS: Proc. Sot. Esp. Biol.
   Med., 1958,99,323.

24. WESSOS, L. G.> JR., .~SD AXSLO~, W. P., JR.: Amer.
  J. Physiol., 1948, 153,465.
25. ULLRICH, K. J., ASD OTHERS: Ibid., 1963, 204, 527.
26. MALVIX, R. L., WILDE, W. S.> VANDER, A. J., AND
  SCLLIVAIZ., L. P.: Ibid.. 1958, 195, 549.

Advances in Clinical Electrodiagnosis-Zohn
     (Conti,lwr/ jrom page 12)

References

1. RODRIQLTEZ, A. A., ASD OESTER, Y. T., in Licht, S.,
  editor: Electrodingnosis and Electromyography,
  2nd ed. New Haven, Conn.: Elizabeth Licht, 1961,
  chap. 12.

2. ROGOFF, J. B.: Clinical electromyography: usefulness
  in differentiating myopathies from neuropathies.
  New York J. Med., 1960,60,512.
3. CLIPPINGER, F. W., GOLDYER, J. L., AXD ROBERTS, J. M.:
  Use of the electromyogram in evahlating upper-es-
  tremity peripheral nerve lesions. J. Bone Joint Surg.
  [-imer.], 1962, 44-A, 1047.

4. MaRIN.4CC1, 8. -4.. ASD COPRVILLE. C. B.: `Elcctrom>-o-
  gram in evaluation of neurological complicaiions of
  spinal anesthesia. J.A.M.A., 1958, 168, 1337.
5. Joz~ssor;, E. W., ASD OLSES~ I(. J.: Clinical vnluc of
  motor nerve conduction velority dcterminntion.
  Ibid., 1960, 172,203O.